AFFYMETRIX INC
S-4/A, 1999-11-16
COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH
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<PAGE>   1


   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON NOVEMBER 16, 1999

                                                      REGISTRATION NO. 333-88987
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549
                            ------------------------


                               AMENDMENT NO. 1 TO


                                    FORM S-4
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------

                                AFFYMETRIX, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

<TABLE>
<S>                                   <C>                                   <C>
              DELAWARE                                8731                               77-0319159
   (STATE OR OTHER JURISDICTION OF        (PRIMARY STANDARD INDUSTRIAL                (I.R.S. EMPLOYER
   INCORPORATION OR ORGANIZATION)          CLASSIFICATION CODE NUMBER)             IDENTIFICATION NUMBER)
</TABLE>

                            3380 CENTRAL EXPRESSWAY
                         SANTA CLARA, CALIFORNIA 95051
                                 (408) 731-5000
  (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE, OF
                   REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)
                            ------------------------

                               VERN NORVIEL, ESQ.
                             SENIOR VICE PRESIDENT,
                    GENERAL COUNSEL AND CORPORATE SECRETARY
                                AFFYMETRIX, INC.
                            3380 CENTRAL EXPRESSWAY
                         SANTA CLARA, CALIFORNIA 95051
                                 (408) 731-5000
 (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE,
                             OF AGENT FOR SERVICE)
                            ------------------------

                                WITH COPIES TO:

<TABLE>
<S>                                                          <C>
                   NEIL T. ANDERSON, ESQ.                                      MICHAEL E. LYTTON, ESQ.
                    SULLIVAN & CROMWELL                                           PALMER & DODGE LLP
                      125 BROAD STREET                                            ONE BEACON STREET
                  NEW YORK, NEW YORK 10004                                   BOSTON, MASSACHUSETTS 02108
                       (212) 558-4000                                               (617) 573-0100
</TABLE>

                            ------------------------

    APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:  As soon as
practicable after the effective date of this Registration Statement and all
other conditions to the merger of Genetic MicroSystems, Inc. with and into GMS
Acquisition, Inc. pursuant to the Agreement and Plan of Merger described in the
enclosed Proxy Statement/Prospectus have been satisfied or waived.

    If the securities being registered on this form are being offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box.  [ ]

    If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the
"Securities Act"), check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering.  [ ] ---------------

    If this form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering.  [ ] ---------------
                            ------------------------

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
- ---------------------------------------------------------------------------------------------------------------------------------
- ---------------------------------------------------------------------------------------------------------------------------------
                                                                     PROPOSED MAXIMUM     PROPOSED MAXIMUM
            TITLE OF EACH CLASS OF                   AMOUNT TO        OFFERING PRICE     AGGREGATE OFFERING       AMOUNT OF
          SECURITIES TO BE REGISTERED            BE REGISTERED(1)       PER SHARE             PRICE(2)       REGISTRATION FEE(3)
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                              <C>               <C>                  <C>                  <C>
Common Stock, par value $0.01 per share,
together with attached rights to purchase
Series B Junior Participating Preferred
Stock..........................................      1,070,000             N.A.              $8,513.91              $2.37
- ---------------------------------------------------------------------------------------------------------------------------------
- ---------------------------------------------------------------------------------------------------------------------------------
</TABLE>

(1) This Registration Statement relates to common stock, par value $0.01 per
    share, together with attached rights to purchase Series B Junior
    Participating Preferred Stock, of the Registrant, Affymetrix, Inc.,
    estimated to be issuable upon the consummation of the merger of Genetic
    MicroSystems, Inc., a Massachusetts corporation, with and into GMS
    Acquisition, Inc., a Massachusetts corporation, pursuant to the Agreement
    and Plan of Merger, dated as of September 10, 1999, by and among Genetic
    MicroSystems, Inc., Affymetrix, Inc., GMS Acquisition, Inc., Jean Montagu as
    Stockholder Representative, and the stockholders of Genetic MicroSystems,
    Inc. set forth in the signature pages to that document.

(2) Genetic MicroSystems, Inc. is a privately held corporation and there is no
    market for its securities. Pursuant to Rule 457(f)(2) of the Securities Act
    of 1933, as amended, the proposed maximum aggregate offering price is based
    upon the book value of the securities of Genetic MicroSystems, Inc. being
    acquired in the proposed merger. The book value of the securities of Genetic
    MicroSystems being acquired in the proposed merger was determined as of
    October 13, 1999 and is a negative number. Since Genetic MicroSystems has an
    accumulated capital deficit, pursuant to Rule 457(f)(2) of the Securities
    Act, one-third of the principal amount, par value or stated capital of
    Genetic MicroSystems' securities is used. The Genetic MicroSystems' shares
    of common stock have no par value and no stated capital and the Genetic
    MicroSystems' shares of convertible preferred stock have a par value of
    $0.01 per share. The number of Genetic MicroSystems' shares of convertible
    preferred stock outstanding and subject to warrants as of October 13, 1999,
    is 2,554,174. The proposed maximum aggregate offering price is equal to: (i)
    2,554,174 multiplied by (ii) 0.01 and divided by (iii) 3.


(3) Calculated by multiplying .000278 by the proposed maximum aggregate offering
    price. This registration fee was previously paid in connection with the
    Registrant's original filing on October 14, 1999.


    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING
PURSUANT TO SECTION 8(a), MAY DETERMINE.

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>   2

                       [GENETIC MICROSYSTEMS LETTERHEAD]

                           -------------------------

To the Stockholders of Genetic MicroSystems, Inc.:


    The Boards of Directors of Genetic MicroSystems, Inc. and Affymetrix, Inc.
have agreed to a merger in which Genetic MicroSystems will become a wholly owned
subsidiary of Affymetrix.



    In the merger, Affymetrix will issue up to 1,070,000 shares of its common
stock, representing less than 4% of the outstanding Affymetrix common stock
after the merger. For each share of Genetic MicroSystems stock that you own, you
will be entitled to receive a fraction of a share of Affymetrix common stock
determined by dividing 1,070,000 by the number of outstanding shares of Genetic
MicroSystems common stock and convertible preferred stock and the outstanding
options and warrants to purchase Genetic MicroSystems common stock and
convertible preferred stock immediately before the effective time of the merger.
In addition, Affymetrix will place 10% of the shares to be issued at the closing
of the merger based on each stockholder's ownership percentage in an escrow fund
to satisfy indemnification obligations of Genetic MicroSystems to Affymetrix.



    We have structured the merger with the intent that you will not recognize
gain or loss for federal income tax purposes on the receipt of Affymetrix common
stock in exchange for your Genetic MicroSystems shares. We have included a more
detailed discussion of the material federal income tax consequences of the
merger in the accompanying proxy statement/prospectus.


    Your Board of Directors has scheduled a special meeting of stockholders to
be held on --, 1999 at Genetic MicroSystems headquarters, 34 Commerce Way,
Woburn, Massachusetts 01801, commencing at 10:00 a.m. local time to vote for
adoption of the merger agreement and the appointment of a stockholder
representative.


    YOUR BOARD OF DIRECTORS HAS CAREFULLY CONSIDERED THE TERMS OF THE PROPOSED
MERGER, HAS DETERMINED THAT THE MERGER AGREEMENT AND THE MERGER ARE IN THE BEST
INTERESTS OF GENETIC MICROSYSTEMS AND ITS STOCKHOLDERS AND UNANIMOUSLY
RECOMMENDS THAT YOU VOTE FOR: ADOPTION OF THE MERGER AGREEMENT AND APPROVAL OF
THE MERGER; THE PROPOSAL THAT THE MERGER DOES NOT CONSTITUTE A LIQUIDATION OR
DISSOLUTION OF GENETIC MICROSYSTEMS; AND APPOINTMENT OF JEAN MONTAGU AS
STOCKHOLDER REPRESENTATIVE.


    I, together with five other stockholders of Genetic MicroSystems, who
together with me beneficially own and have voting control over approximately
69.5% of the outstanding shares of Genetic MicroSystems common stock and
approximately 72% of the outstanding shares of Genetic MicroSystems convertible
preferred stock, have agreed to vote for adoption of the merger proposals. These
shares represent more than the number of votes necessary to adopt the merger
agreement and approve the merger.

    Please complete, sign and date the enclosed proxy card and return it in the
enclosed self-addressed and stamped envelope, even if you plan to attend the
special meeting. If you sign, date and mail your proxy card without indicating
how you wish to vote, your proxy will be counted as a vote in favor of adopting
the merger proposals.

    We appreciate your support in this very important transaction. We are very
enthusiastic about the merger with Affymetrix, and are confident that the
combined company will grow and prosper in a competitive marketplace. On behalf
of the board of directors of Genetic MicroSystems, I urge you to vote "FOR"
approval of the merger proposals.


    PLEASE READ THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS CAREFULLY FOR
DETAILED INFORMATION ABOUT THE PROPOSED MERGER CAREFULLY AND TO CONSIDER THE
RISK FACTORS RELATING TO THE MERGER BEGINNING ON PAGE 15 OF THE PROXY
STATEMENT/PROSPECTUS.


                                          Sincerely,

                                          /s/ Jean Montagu

                                          Jean Montagu
                                          President and Chief Executive Officer
<PAGE>   3

                       [GENETIC MICROSYSTEMS LETTERHEAD]

                           -------------------------

                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
                             TO BE HELD ON --, 1999

TO THE STOCKHOLDERS OF GENETIC MICROSYSTEMS, INC.:

     NOTICE IS HEREBY GIVEN that a Special Meeting of Stockholders of Genetic
MicroSystems, Inc. will be held on --, 1999, at 10:00 a.m., local time, at the
offices of Genetic MicroSystems located at 34 Commerce Way, Woburn,
Massachusetts 01801, for the following purposes:

          1. To consider and vote upon a proposal to adopt the Agreement and
     Plan of Merger, dated as of September 10, 1999, by and among Affymetrix,
     Inc., a Delaware corporation, GMS Acquisition, Inc., a Massachusetts
     corporation wholly owned directly by Affymetrix, Genetic MicroSystems,
     Inc., a Massachusetts corporation, Jean Montagu as Stockholder
     Representative and the stockholders of Genetic MicroSystems, Inc. listed in
     the signature pages of that document, pursuant to which, among other
     things:


        - Each outstanding share of Genetic MicroSystems common stock and
          convertible preferred stock will convert into the right to receive a
          fraction of a share of Affymetrix common stock, based on an exchange
          ratio described in the accompanying proxy statement/prospectus.



        - Genetic MicroSystems will be merged into GMS Acquisition, Inc. as a
          result of which Genetic MicroSystems will become a wholly owned
          subsidiary of Affymetrix.



        - Affymetrix will assume each outstanding option and warrant to purchase
          Genetic MicroSystems common stock or convertible preferred stock,
          which will convert into an option or warrant to purchase a fraction of
          a share of Affymetrix common stock.


        - 10% of the shares to be issued at the closing of the merger will be
          placed into an escrow fund.


          2. To have the holders of shares of Genetic MicroSystems Series A
     convertible preferred stock vote on the proposal not to treat the merger as
     a liquidation or dissolution of Genetic MicroSystems.


          3. To appoint Jean Montagu as Stockholder Representative to act on
     behalf of the current Genetic MicroSystems stockholders in connection with
     the escrow fund established pursuant to the terms of the merger agreement
     and the escrow agreement.

          4. To transact such other business as may properly come before the
     special meeting or any adjournment(s) of the special meeting.
<PAGE>   4


     Stockholders of record at the close of business on --, 1999 are entitled to
notice of, and to vote at, the special meeting and any adjournment or
postponement of the special meeting. Each record holder of common stock and
convertible preferred stock will be entitled to one vote for each share held on
each matter that stockholders will act upon at the special meeting, except with
respect to Item 2, upon which only holders of Genetic MicroSystems Series A
convertible preferred stock will be entitled to vote.



     Please complete, sign, date and promptly return the enclosed proxy card in
the enclosed self-addressed and stamped envelope even if you plan to attend the
special meeting. If you decide to attend the special meeting you may vote in
person even if you have returned a proxy.



     Holders of outstanding shares of Genetic MicroSystems common stock and
convertible preferred stock have the right to dissent from the merger and
receive payment for their shares. The accompanying proxy statement/prospectus
describes these rights in greater detail under the caption "Appraisal Rights"
found in Appendix E to the attached document.


     PLEASE DO NOT SEND ANY STOCK CERTIFICATES WITH YOUR PROXY AT THIS TIME.

                                          By Order of the Board of Directors,

                                               /s/ Peter Lewis

                                          Peter Lewis
                                          Corporate Clerk of Genetic
                                          MicroSystems, Inc.

Woburn, Massachusetts

- --, 1999

<PAGE>   5

      THIS DOCUMENT AND THE INFORMATION CONTAINED HEREIN IS SUBJECT TO
      COMPLETION OR AMENDMENT. A REGISTRATION STATEMENT RELATING TO THESE
      SECURITIES HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.
      THESE SECURITIES MAY NOT BE SOLD NOR MAY OFFERS TO BUY BE ACCEPTED PRIOR
      TO THE TIME THE REGISTRATION STATEMENT BECOMES EFFECTIVE. THIS DOCUMENT
      SHALL NOT CONSTITUTE AN OFFER TO SELL OR THE SOLICITATION OF ANY OFFER TO
      BUY NOR SHALL THERE BE ANY SALE OF THESE SECURITIES IN ANY STATE IN WHICH
      SUCH OFFER, SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR TO REGISTRATION
      OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.


                 Subject to completion, dated November 16, 1999


[AFFYMETRIX GENECHIP LOGO][GENETIC MICROSYSTEMS, INC. LOGO]

                                PROXY STATEMENT
                     FOR SPECIAL MEETING OF STOCKHOLDERS OF
                           GENETIC MICROSYSTEMS, INC.

                                 PROSPECTUS OF
                                AFFYMETRIX, INC.
                           UP TO 1,070,000 SHARES OF
                                  COMMON STOCK


     Affymetrix, Inc. and Genetic MicroSystems, Inc. have signed a merger
agreement. As a result of the proposed merger, Genetic MicroSystems will become
a wholly owned subsidiary of Affymetrix.



     We are providing this document to you in connection with the Genetic
MicroSystems board of directors' solicitation of proxies for use at a special
meeting of the stockholders of Genetic MicroSystems.



     THIS DOCUMENT PROVIDES YOU WITH DETAILED INFORMATION ABOUT THE MERGER
AGREEMENT AND THE PROPOSED MERGER. AFFYMETRIX PROVIDED THE INFORMATION
CONCERNING AFFYMETRIX. GENETIC MICROSYSTEMS PROVIDED THE INFORMATION CONCERNING
GENETIC MICROSYSTEMS. PLEASE SEE "WHERE YOU CAN FIND MORE INFORMATION" ON PAGE
81 FOR ADDITIONAL INFORMATION ON AFFYMETRIX.


     Affymetrix is a Delaware corporation and the shares of Affymetrix common
stock trade on the NASDAQ National Market under the symbol "AFFX." Genetic
MicroSystems is a privately held Massachusetts corporation with fewer than
ninety stockholders.


     WE STRONGLY URGE YOU TO READ AND CONSIDER CAREFULLY THIS DOCUMENT IN ITS
ENTIRETY, INCLUDING THE MATTERS REFERRED TO UNDER "RISK FACTORS" BEGINNING ON
PAGE 15.



NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED THESE SECURITIES OR DETERMINED IF THIS
PROXY STATEMENT/PROSPECTUS IS ACCURATE OR ADEQUATE. ANY REPRESENTATION TO THE
CONTRARY IS A CRIMINAL OFFENSE.


      We are first mailing this proxy statement/prospectus dated --, 1999
                  and the form of proxy on or about --, 1999.
<PAGE>   6

                               TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                      PAGE
                                      ----
<S>                                   <C>
Questions and Answers About the
  Merger............................    ii
Summary.............................     1
Summary of Selected Historical
  Information of Affymetrix.........     7
Summary of Selected Historical
  Financial Information of Genetic
  MicroSystems......................     8
Pro Forma Combined Financial
  Information of Affymetrix.........     9
Unaudited Selected Pro Forma
  Condensed Combined Financial
  Data..............................    10
Comparative Per Share Information...    11
Market Price and Dividend
  Information.......................    13
Risk Factors........................    15
Cautionary Statement Concerning
  Forward-Looking Statements........    26
The Genetic MicroSystems Special
  Meeting...........................    27
Appraisal Rights....................    29
</TABLE>



<TABLE>
<CAPTION>
                                      PAGE
                                      ----
<S>                                   <C>
The Merger..........................    31
The Merger Agreement................    39
Stock Option Agreement..............    52
Escrow Agreement....................    54
Stockholder Voting Agreements.......    55
Stock Ownership of Directors,
  Executive Officers and Principal
  Stockholders......................    56
Interests of Certain Persons in the
  Merger............................    58
Genetic MicroSystems' Management's
  Discussion and Analysis of the
  Financial Condition and Results of
  Operations........................    62
Description of Affymetrix Capital
  Stock.............................    65
Comparison of Stockholder Rights....    71
Validity of Shares..................    81
Experts.............................    81
Where You Can Find More
  Information.......................    81
</TABLE>


                               LIST OF APPENDICES


Appendix A -- Agreement and Plan of Merger, dated as of September 10, 1999, by
              and among Affymetrix, Inc., GMS Acquisition, Inc., Genetic
              MicroSystems, Inc., Jean Montagu, as Stockholder Representative,
              and the stockholders of Genetic MicroSystems, Inc. listed in the
              attached signature pages


Appendix B -- Stock Option Agreement, dated as of September 10, 1999, between
              Affymetrix, Inc. and Genetic MicroSystems, Inc.

Appendix C -- Escrow Agreement, dated as of September 10, 1999, among Genetic
              MicroSystems, Inc., Affymetrix, Inc., GMS Acquisition, Inc., Jean
              Montagu, as Stockholder Representative, and Bank One Trust
              Company, N.A., as Escrow Agent

Appendix D -- Form of Stockholder Voting Agreement

Appendix E -- Sections 85 through 98 of the Massachusetts Business Corporation
              Law Regarding Appraisal Rights

Appendix F -- Genetic MicroSystems' Audited Financial Statements for the Year
              Ended December 31, 1998 and the period from August 7, 1997 (date
              of inception) to December 31, 1997, and Unaudited Condensed
              Financial Statements for the Six Months ended July 3, 1999 and
              June 30, 1998

                                        i
<PAGE>   7

                     QUESTIONS AND ANSWERS ABOUT THE MERGER


Q:  WHAT DO I NEED TO DO NOW?



A:  Just indicate on your proxy card how you want to vote, and sign and mail it
    in the enclosed self-addressed and stamped envelope as soon as possible, so
    that your shares may be represented at the special meeting. If you sign and
    send in your proxy and do not indicate how you want to vote, your proxy will
    be counted as a vote FOR adoption of the merger agreement. We will treat
    your failure to vote or any abstention from voting as a vote against the
    merger agreement.


Q:  CAN I CHANGE MY VOTE AFTER I HAVE MAILED MY SIGNED PROXY CARD?


A:  You can change your vote at any time before someone votes your proxy at the
    special meeting. You can do this in one of the following three ways:



    - you can send a written notice with your signature stating that you would
      like to revoke your proxy. If you choose this method, you must submit your
      notice of revocation to Genetic MicroSystems at 34 Commerce Way, Woburn,
      Massachusetts 01801, Attention: Peter Lewis, Clerk;


    - you can complete and submit a new proxy card. If you choose this method,
      you must submit your new proxy card to Genetic MicroSystems at 34 Commerce
      Way, Woburn, Massachusetts 01801, Attention: Peter Lewis, Clerk; or

    - you can attend the special meeting and vote in person. Simply attending
      the special meeting, however, will not revoke your proxy; you must vote at
      the special meeting.


Q:  SHOULD I SEND IN MY STOCK CERTIFICATES NOW?



A:  No. After the merger is completed, we will send you written instructions for
    exchanging your stock certificates.


Q:  WHEN DO YOU EXPECT THE MERGER TO BE COMPLETED?


A:  Affymetrix and Genetic MicroSystems are working towards completing the
    merger in or before January 2000. Genetic MicroSystems must obtain
    stockholder approval and intends to complete the merger as soon as possible
    after the special meeting. Either party may terminate the merger agreement
    if the merger is not consummated by February 15, 1999.


                                       ii
<PAGE>   8

                                    SUMMARY


     This summary highlights what we believe is the most important information
about the merger and may not contain all of the information that is important to
you. For a complete understanding of the merger and our businesses, you should
read carefully this entire document and the documents we refer to in this
document. See "Where You Can Find More Information" on page 81. The merger
agreement is attached as Appendix A to this document. We encourage you to read
it, as well as the documents attached as Appendices B through E as these are
important legal documents that govern the merger. We have included page
references to other parts of this document in parentheses to direct you to a
more complete description of the topics presented in this summary.



                                   WHAT WE DO


AFFYMETRIX, INC.

3380 Central Expressway
Santa Clara, California 95051
(408) 731-5000


     Affymetrix is in the business of developing and selling DNA probe arrays
and related products that allow researchers to study genetic information in
order to help improve the diagnosis, monitoring and treatment of disease. DNA,
which is a common abbreviation for deoxyribonucleic acid, provides the molecular
blueprint of every living organism and is made up of individual genes which
determine what attributes or characteristics a particular organism will have.
DNA probe array refers to a collection of DNA molecules attached to a surface,
such as a piece of glass, and designed for viewing under a microscope-type
device known as a scanner.


GENETIC MICROSYSTEMS, INC.

34 Commerce Way
Woburn, Massachusetts 01801
(781) 932-9333


     Genetic MicroSystems is a privately held corporation with fewer than ninety
stockholders primarily engaged in the manufacture of biotechnology research
equipment. Genetic MicroSystems was incorporated in Massachusetts in 1997 to
develop products for DNA probe array analysis. Genetic MicroSystems advances
genetics research and drug discovery by providing systems that enable scientists
to make and use DNA probe arrays in their own labs and in experiments of their
own design.

GMS ACQUISITION, INC.

3380 Central Expressway
Santa Clara, California 95051
(408) 731-5000


     GMS Acquisition is a wholly owned subsidiary of Affymetrix. The parties
organized GMS Acquisition for use in the merger.



                                 EXCHANGE RATIO



     Affymetrix will send shares of its stock to you as payment in the merger.
Affymetrix will calculate the number of its shares it is sending to you
immediately before the completion of the merger by dividing 1,070,000 by the
total number of the Genetic MicroSystems shares outstanding and Genetic
MicroSystems shares subject to options or warrants.



     Each outstanding option or warrant to purchase Genetic MicroSystems common
stock or convertible preferred stock will convert into an option or warrant to
purchase the number of shares of Affymetrix common stock that Affymetrix would
have delivered to the holder in the merger if the holder had exercised the
option or warrant immediately before the closing of the merger and Affymetrix
will adjust the exercise price appropriately.



     Affymetrix will not send you fractional shares of its common stock.
Instead, Affymetrix will send you the cash value, without interest, of any
fractional share of its common stock you might otherwise have been entitled to
receive.



     For example, if you are entitled to receive 100.10 shares of Affymetrix
common stock, you


                                        1
<PAGE>   9


will receive a certificate for 100 shares of Affymetrix common stock, and cash
equal to the value of a tenth of a share of Affymetrix common stock. To obtain
this cash amount, the exchange agent will sell all fractional shares shortly
after the merger so the amount of money to be distributed will depend on the
trading price of Affymetrix common stock at that time.



     After the merger, existing Genetic MicroSystems stockholders will own less
than 4% of the outstanding Affymetrix common stock.



              APPOINTMENT OF STOCKHOLDER REPRESENTATIVE (PAGE 49)



     The merger agreement provides that Genetic MicroSystems stockholders who
vote in favor of the merger or who receive or accept shares of Affymetrix common
stock as the merger consideration consent to the appointment of Jean Montagu as
stockholder representative and consent to the stockholder representative's
performing all rights and obligations of the stockholder representative under
the merger agreement and the escrow agreement. For more detailed information on
the escrow arrangement, see "Escrow Agreement" on page 54.



                        STOCK OPTION AGREEMENT (PAGE 52)



     Affymetrix and Genetic MicroSystems have entered into a stock option
agreement granting Affymetrix an option to purchase approximately 19.9% of
Genetic MicroSystems' outstanding capital stock at $21.50 per share. The stock
option is exercisable under the same circumstances under which a termination fee
is payable under the merger agreement. We have attached the stock option
agreement as Appendix B to this document.



     If Affymetrix exercises the stock option, Genetic MicroSystems may
repurchase all or any portion of the Genetic MicroSystems common stock issued
pursuant to the stock option. Affymetrix' total profit allowed under the stock
option agreement is $5 million. See "Stock Option Agreement -- Effect of Stock
Option Agreement" on page 53 for a discussion of the effect of the stock option
agreement.



                           ESCROW AGREEMENT (PAGE 54)



     The escrow agreement provides that Affymetrix will deposit 10% of the
aggregate number of shares of Affymetrix common stock it issues at the closing
of the merger with Bank One Trust Company, NA, as escrow agent. Affymetrix will
deposit these shares based on each stockholder's ownership percentage in Genetic
MicroSystems for a period not to exceed one year. These shares of Affymetrix
common stock will be used to satisfy the indemnification obligations that the
stockholder representative and the other stockholders of Genetic MicroSystems
owe to Affymetrix. Shares that Affymetrix does not use to satisfy claims will
be:



- - distributed by the escrow agent to the stockholders of Genetic MicroSystems
  based on each stockholder's relative ownership in Genetic MicroSystems; and



- - released five business days after the one-year anniversary of the closing date
  of the merger.



     Affymetrix, however, can instruct the escrow agent not to distribute the
escrowed shares until any unpaid claim has been resolved. We have attached a
copy of the escrow agreement to this document as Appendix C. We encourage you to
read the escrow agreement as it is the legal document that governs the
disposition of the escrow fund.



   LIABILITY OBLIGATIONS OF GENETIC MICROSYSTEMS STOCKHOLDERS AND AFFYMETRIX


                                   (PAGE 49)



     For a period of one year after the effective time of the merger, the
stockholders of Genetic MicroSystems are required individually and as a


                                        2
<PAGE>   10


group to pay Affymetrix and its affiliates for any damages arising or resulting
from:



- - any breach of a representation or warranty;



- - any breach of any covenant or obligation of Genetic MicroSystems; or



- - any breach of, or failure to assign to Affymetrix all of, the rights under any
  contract to which Genetic MicroSystems is a party.



     For a period of one year after the effective time of the merger, Affymetrix
will pay the stockholders of Genetic MicroSystems any damages arising from:



- - any breach of a representation or warranty made by Affymetrix; or



- - any breach of any covenant or obligation of Affymetrix.



     There are limitations on the amount of damages that Genetic MicroSystems'
stockholders and Affymetrix must pay. The indemnification provisions of the
merger agreement are not the exclusive remedy for Affymetrix. Affymetrix will
have the right to recover damages from the Genetic MicroSystems stockholders if
Affymetrix wins a judgment from a court.



                           APPRAISAL RIGHTS (PAGE 29)



     Under Massachusetts law, Genetic MicroSystems stockholders are entitled to
appraisal rights if they do not vote to approve the merger agreement and
otherwise comply with Sections 86 to 98 of the Massachusetts Business
Corporation Law. If you wish to exercise appraisal rights, you must take the
steps described in the section entitled "Appraisal Rights" and found in Appendix
E. If you do not strictly comply with the statutory requirements, you may lose
your appraisal rights.



                          MATERIAL FEDERAL INCOME TAX


                             CONSEQUENCES (PAGE 35)



     We structured the merger with the intent that you will not recognize gain
or loss for federal income tax purposes on your receipt of Affymetrix common
stock in exchange for your shares of Genetic MicroSystems stock. To review the
tax consequences to stockholders in greater detail, see "The Merger -- Material
Federal Income Tax Consequences" on page 35.



                         NASDAQ NATIONAL MARKET TRADING
                                   (PAGE 38)



     As a condition to the merger, Affymetrix must file the appropriate NASDAQ
notification form and pay the applicable fee. Therefore, if we complete the
merger, you will be able to trade the shares of Affymetrix common stock you
receive in the merger on the NASDAQ National Market.



                         ACCOUNTING TREATMENT (PAGE 37)



     Affymetrix and Genetic MicroSystems expect the merger to qualify as a
pooling-of-interests for accounting and financial reporting purposes, which
means that Affymetrix and Genetic MicroSystems will be treated as if they had
always been combined for accounting and financial reporting purposes.



                   COMPARISON OF STOCKHOLDER RIGHTS (PAGE 71)



     Your rights as Genetic MicroSystems' stockholders are currently governed by
Genetic MicroSystems' charter and bylaws and Massachusetts law. After the
merger, Affymetrix' charter and bylaws and Delaware corporate law will govern
your rights as a stockholder of Affymetrix. Your rights as a Affymetrix
stockholder will differ in some respects from your rights as a Genetic
MicroSystems stockholder. These differences are summarized in the "Comparison of
Stockholder Rights" on page 71.


                                        3
<PAGE>   11


      GENETIC MICROSYSTEMS' REASONS FOR THE MERGER; RECOMMENDATION OF THE


                      GENETIC MICROSYSTEMS BOARD (PAGE 33)



     THE BOARD OF DIRECTORS OF GENETIC MICROSYSTEMS UNANIMOUSLY RECOMMENDS THAT
YOU VOTE FOR: ADOPTION OF THE MERGER AGREEMENT AND APPROVAL OF THE MERGER; THE
PROPOSAL THAT THE MERGER DOES NOT CONSTITUTE A LIQUIDATION OF GENETIC
MICROSYSTEMS; AND APPOINTMENT OF JEAN MONTAGU AS STOCKHOLDER REPRESENTATIVE.


                              DATE, TIME AND PLACE

                        OF THE SPECIAL MEETING (PAGE 27)


     The special meeting will be held on --, at 10:00 a.m., local time, at
Genetic MicroSystems' executive offices, 34 Commerce Way, Woburn, Massachusetts
01801.


   STOCKHOLDERS ENTITLED TO VOTE AT THE SPECIAL MEETING; VOTE REQUIRED (PAGES
                                     27-28)



     The close of business on --, 1999 is the record date for the special
meeting. Only Genetic MicroSystems stockholders on the record date are entitled
to notice of and to vote at the special meeting. On the record date, there were
1,006,702 shares of Genetic MicroSystems common stock and 2,431,977 shares of
Genetic MicroSystems Series A and Series B convertible preferred stock
outstanding.



     The holders of:



- - two-thirds of the shares of Genetic MicroSystems common stock;



- - two-thirds of the shares of Genetic MicroSystems convertible preferred stock;
  and



- - a majority of the shares of Genetic MicroSystems Series A convertible
  preferred stock



must adopt the merger agreement at the special meeting.



Holders of a majority of the shares of Genetic MicroSystems Series A convertible
preferred stock also must vote not to treat the merger as a liquidation or
dissolution of Genetic MicroSystems.



     In addition, Genetic MicroSystems must obtain the affirmative vote of a
majority of Genetic MicroSystems common stock and convertible preferred stock,
taken as a class, to appoint Jean Montagu as stockholder representative to act
on behalf of the Genetic MicroSystems stockholders in connection with the escrow
fund.



     Each share of Genetic MicroSystems common stock and convertible preferred
stock is entitled to one vote on each matter to be acted upon at the special
meeting, except that only holders of Genetic MicroSystems Series A convertible
preferred stock are entitled to vote on whether or not to treat the merger as a
liquidation or dissolution of Genetic MicroSystems.



                    STOCKHOLDER VOTING AGREEMENTS (PAGE 55)



     Affymetrix has entered into stockholder voting agreements with Jean
Montagu, the Chairman, Chief Executive Officer and founder of Genetic
MicroSystems, and with five other stockholders of Genetic MicroSystems who are
all either family members of Jean Montagu or executive officers or directors of
Genetic MicroSystems. These six stockholders, who together beneficially own and
have voting control over approximately 69.5% of the shares of Genetic
MicroSystems common stock and approximately 72% of the shares of Genetic
MicroSystems convertible preferred stock, have agreed to vote for adoption of
the merger proposals. Their shares represent more than the number of votes
necessary to adopt the merger agreement and approve the merger.



     A form of the stockholder voting agreement is attached to this document as
Appendix D.


                                        4
<PAGE>   12

                         STOCK OWNERSHIP OF DIRECTORS,
                        EXECUTIVE OFFICERS AND PRINCIPAL
                   STOCKHOLDERS/INTERESTS OF CERTAIN PERSONS

                                   (PAGE 56)



     You should be aware that individual directors and executive officers of
Genetic MicroSystems have interests in the merger that may be different from
your interests. Directors, officers and employees of Genetic MicroSystems who
hold stock subject to repurchase rights will receive benefits upon completion of
the merger, including elimination of those repurchase rights. Genetic
MicroSystems' board of directors was aware of these interests and considered
them in approving the merger agreement.


     As of the record date for the special meeting, the directors and executive
officers of Genetic MicroSystems, as a group, beneficially owned approximately
- --% of the outstanding Genetic MicroSystems common stock and approximately --%
of the outstanding Genetic MicroSystems convertible preferred stock.


                            CONDITIONS TO THE MERGER


                                   (PAGE 41)



     We will complete the merger only if we satisfy or waive several conditions,
including the following:



- - no court order or law in effect prohibits the merger or makes the merger
  illegal;



- - each of Affymetrix and Genetic MicroSystems receives a letter from Ernst &
  Young LLP regarding the appropriateness of pooling-of-interests accounting for
  the merger;



- - each of Affymetrix and Genetic MicroSystems certifies to the other the
  accuracy of representations and warranties contained in the merger agreement;



- - each of Genetic MicroSystems and Affymetrix certifies to the other that it has
  performed in all material respects all obligations required to be performed
  under the merger agreement;


- - Affymetrix and Genetic MicroSystems each receives a legal opinion confirming
  that the merger will qualify as a tax-free reorganization;



- - Affymetrix and Genetic MicroSystems obtain the consent of each person whose
  consent is required under any material contract; and



- - Affymetrix receives the resignations of each director of Genetic MicroSystems.



                      TERMINATION OF THE MERGER AGREEMENT


                                   (PAGE 47)



     Affymetrix and Genetic MicroSystems can agree to terminate the merger
agreement without completing the merger. Either company can terminate the merger
agreement if any of the following occurs:



- - the merger is not completed by February 15, 2000;



- - the Genetic MicroSystems stockholders do not give the necessary approval at
  the special meeting; or



- - any order permanently restraining, enjoining or otherwise prohibiting the
  merger becomes final and non-appealable.


     In addition, Genetic MicroSystems may terminate the merger agreement as a
result of an acquisition proposal from a potential acquiror if:

- - Genetic MicroSystems is not in breach of any of the terms of the merger
  agreement; and


     - The board of directors of Genetic MicroSystems authorizes Genetic
       MicroSystems to enter into a binding written agreement concerning a
       superior proposal; and



     - Genetic MicroSystems notifies Affymetrix in writing that it intends to
       enter into an agreement concerning a superior proposal; and



     - Affymetrix does not make, within five business days after Genetic


                                        5
<PAGE>   13


       MicroSystems' notice, an offer that is at least as favorable as the
       competing proposal; and



     - Genetic MicroSystems pays Affymetrix the required termination and expense
       fees.



- - Affymetrix or GMS Acquisition materially breaches a provision of the merger
  agreement that is not curable or, if curable, is not cured within 30 days
  after written notice.


     In addition, Affymetrix may terminate the merger agreement if:


- - the Genetic MicroSystems board of directors adversely modifies its approval of
  the merger agreement;



- - the Genetic MicroSystems board of directors fails to reconfirm its
  recommendation of the merger agreement within five business days after a
  written request by Affymetrix to do so;



- - Genetic MicroSystems materially breaches the merger agreement and the breach
  is not curable or, if curable, is not cured within 30 days after written
  notice; or



- - Genetic MicroSystems breaches its covenant set forth on page 45 under the
  heading "No Solicitation of Acquisition Proposals."



              TERMINATION FEE AND EXPENSE REIMBURSEMENT (PAGE 49)



     Genetic MicroSystems must pay Affymetrix a termination fee equal to
$2,500,000 and reimburse Affymetrix' expenses up to $1,000,000 if the merger
agreement is terminated under the following circumstances:



- - Genetic MicroSystems terminates the merger agreement because of a superior
  proposal.


- - Affymetrix terminates the merger agreement because:


     - the Genetic MicroSystems board of directors adversely modifies its
       approval of the merger agreement;



     - the Genetic MicroSystems board of directors fails to reconfirm its
       recommendation of the merger agreement within five business days after a
       written request by Affymetrix to do so; or



     - Genetic MicroSystems breaches its covenant set forth on page 45 under the
       heading "No Solicitation of Acquisition Proposals."



                         REGULATORY APPROVALS (PAGE 37)



     The Hart-Scott-Rodino Antitrust Improvements Act prohibits Affymetrix and
Genetic MicroSystems from completing the merger until Affymetrix and Genetic
MicroSystems have furnished information and materials to the Antitrust Division
of the Department of Justice and the Federal Trade Commission and the required
waiting period has ended. On October 6, 1999, Affymetrix and Genetic
MicroSystems each filed the required notification and report forms. The required
waiting period expired on November 5, 1999.


                                        6
<PAGE>   14

       SUMMARY OF SELECTED HISTORICAL FINANCIAL INFORMATION OF AFFYMETRIX


     Affymetrix is providing the following information to aid you in your
analysis of the financial aspects of the merger. Affymetrix derived this
information from audited financial statements for 1994 through 1998 and
unaudited financial statements for the six months ended June 30, 1998 and 1999.
In the opinion of Affymetrix, this information reflects all adjustments,
consisting only of normal recurring adjustments, necessary for a fair
presentation of the results of operations and financial condition for the six
months ended June 30, 1998 and 1999. Results for interim periods should not be
considered indicative of results for any other periods or for the year. This
information is only a summary and you should read it in conjunction with
Affymetrix' historical financial statements and related notes and "Management's
Discussion and Analysis of Financial Condition and Results of Operations"
contained in Affymetrix' annual reports, quarterly reports and other information
on file with the Securities and Exchange Commission and incorporated by
reference in this document. See "Where You Can Find More Information" on page
81.


<TABLE>
<CAPTION>
                                                                                       SIX MONTHS ENDED
                                         FISCAL YEARS ENDED DECEMBER 31,                   JUNE 30,
                               ----------------------------------------------------   -------------------
                                 1994       1995       1996       1997       1998       1998       1999
                               --------   --------   --------   --------   --------   --------   --------
                                                 (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                            <C>        <C>        <C>        <C>        <C>        <C>        <C>
HISTORICAL STATEMENT OF OPERATIONS DATA:
Total revenue................  $  1,574   $  4,625   $ 11,972   $ 19,765   $ 52,025   $ 20,823   $ 39,514
Loss from operations.........   (10,212)   (11,628)   (16,537)   (27,659)   (28,549)   (14,197)   (15,571)
Net loss.....................    (9,680)   (10,747)   (12,227)   (22,526)   (23,130)   (11,826)   (13,243)
Preferred stock dividends....         -          -          -          -     (2,321)      (695)    (1,626)
Net loss attributable to
  common stockholders........    (9,680)   (10,747)   (12,227)   (22,526)   (25,451)   (12,512)   (14,869)
Basic and diluted net loss
  per common share...........  $  (0.55)  $  (0.61)  $  (0.61)  $  (0.99)  $  (1.11)  $  (0.55)  $  (0.63)
Shares used in computing
  basic and diluted net loss
  per common share...........    17,563     17,664     20,131     22,644     22,915     22,859     23,744
</TABLE>

<TABLE>
<CAPTION>
                                                            AS OF DECEMBER 31,                     AS OF
                                           ----------------------------------------------------   JUNE 30,
                                             1994       1995       1996       1997       1998       1999
                                           --------   --------   --------   --------   --------   --------
                                                                   (IN THOUSANDS)
<S>                                        <C>        <C>        <C>        <C>        <C>        <C>
HISTORICAL BALANCE SHEET DATA:
Cash, cash equivalents and short-term
investments..............................  $ 17,805   $ 38,883   $108,982   $ 71,573   $ 80,568   $89,261
Working capital..........................    15,677     36,070    107,668     71,553     80,387    95,076
Total assets.............................    19,945     44,594    118,900    101,170    136,428   158,185
Long-term liabilities, net of current
  portion(1).............................     7,135        948        741        513      5,261     5,135
Convertible redeemable preferred
  stock(2)...............................         -          -          -          -     49,857    49,857
Total stockholders' equity...............     9,254     38,561    112,533     91,036     66,750    85,113
</TABLE>

- -------------------------
(1) Excludes $150 million of 5% Convertible Subordinated Notes due 2006, issued
    by Affymetrix in September 1999.
(2) Convertible redeemable preferred stock was converted into 1,257,229 shares
    of common stock in August 1999.
                                        7
<PAGE>   15

  SUMMARY OF SELECTED HISTORICAL FINANCIAL INFORMATION OF GENETIC MICROSYSTEMS

     Genetic MicroSystems is providing the following information to aid you in
your analysis of the financial aspects of the merger. Genetic MicroSystems
derived this information from audited financial statements for the year ended
December 31, 1998 and for the period from August 7, 1997 (date of inception) to
December 31, 1997 and unaudited financial statements for the six months ended
June 30, 1998 and July 3, 1999. In the opinion of Genetic MicroSystems, this
information reflects all adjustments, consisting only of normal recurring
adjustments, necessary for a fair presentation of the results of operations and
financial condition for the six months ended June 30, 1998 and July 3, 1999.
Results for interim periods should not be considered indicative of results for
any other periods or for the year. This information is only a summary and you
should read it in conjunction with Genetic MicroSystems' historical financial
statements and related notes included elsewhere in this document. See Appendix F
to this document.

<TABLE>
<CAPTION>
                                               PERIOD FROM
                                              AUGUST 7, 1997
                                                 (DATE OF                      SIX MONTHS ENDED
                                              INCEPTION) TO     YEAR ENDED    -------------------
                                               DECEMBER 31,    DECEMBER 31,   JUNE 30,    JULY 3,
                                                   1997            1998         1998      1999(1)
                                              --------------   ------------   --------    -------
                                                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                           <C>              <C>            <C>         <C>
HISTORICAL STATEMENT OF OPERATIONS DATA:
Revenue.....................................     $    --         $   388      $    --     $5,082
Loss from operations........................        (481)         (4,337)      (1,776)    (1,437)
Net loss....................................        (254)         (3,670)      (1,614)    (1,371)
Basic and diluted net loss per share........     $(25.38)        $ (6.21)     $(10.35)    $(1.36)
Shares used in computing basic and diluted
  net loss per share........................          10             591          155      1,009
</TABLE>

<TABLE>
<CAPTION>
                                                                   AS OF
                                                                DECEMBER 31,       AS OF
                                                              ----------------    JULY 3,
                                                               1997      1998      1999
                                                              ------    ------    -------
                                                                    (IN THOUSANDS)
<S>                                                           <C>       <C>       <C>
HISTORICAL BALANCE SHEET DATA:
Cash, cash equivalents and short-term investments...........  $1,552    $4,365    $ 2,527
Working capital.............................................     718     4,544      3,744
Total assets................................................   1,658     5,758      6,393
Long-term liabilities.......................................      --     3,050      3,038
Convertible redeemable preferred stock......................      --     2,951      3,672
Total shareholders' equity..................................     812      (786)    (2,169)
</TABLE>

- ---------------

(1) Effective January 1, 1999, for quarterly interim periods, Genetic
    MicroSystems adopted a fiscal quarter ending on the Saturday nearest the end
    of the calendar quarter.
                                        8
<PAGE>   16

             PRO FORMA COMBINED FINANCIAL INFORMATION OF AFFYMETRIX

     The following describes the pro forma effect of the merger on

          - Affymetrix' unaudited statement of operations for the six months
            ended June 30, 1998 and 1999 and the years ended December 31, 1997
            and 1998; and

          - its unaudited balance sheet as of June 30, 1999, based on the
            historical financial statements of Affymetrix and Genetic
            MicroSystems.


     For purposes of the pro forma combined financial information, we have
combined Genetic MicroSystems' results of operations for the six month period
ended July 3, 1999 with Affymetrix' results of operations for the six month
period ended June 30, 1999.



     You should read the unaudited pro forma combined financial information and
the accompanying notes in conjunction with the historical financial information
and related notes of Affymetrix, incorporated by reference in this document, and
of Genetic MicroSystems included elsewhere in this document.



     We provide the unaudited pro forma combined financial information for
informational purposes only. This financial information does not purport to
represent what Affymetrix' financial position and results of operations would
actually have been had the merger and other pro forma adjustments in fact
occurred at the dates indicated.


     The unaudited pro forma combined statement of operations data and combined
balance sheet data of Affymetrix illustrate the estimated effects of the merger
as if that transaction had occurred at the beginning of the periods presented
and end of the periods presented, respectively.


     Management of Affymetrix and Genetic MicroSystems intend to receive a
letter, as a condition to closing, from their independent auditors regarding the
appropriateness of pooling-of-interests accounting for the merger if closed and
completed under the terms of the merger agreement. Under this method of
accounting, the recorded historical cost basis of the assets and liabilities of
Affymetrix and Genetic MicroSystems will be carried forward to the operations of
the combined company at their historical recorded amounts. Results of operations
of the combined company will include the results of operations of Affymetrix and
Genetic MicroSystems for the entire fiscal period in which the combination
occurs, and the historical results of operations of the separate companies for
fiscal years prior to the merger will be combined and reported as the results of
operations of the combined company. We have not made any adjustments to the
unaudited condensed pro forma financial statement data of Affymetrix and Genetic
MicroSystems to conform the accounting policies of the combined company as we do
not expect the nature and amounts of any adjustments to be significant.



     We cannot fully assess some of the conditions to be met for
pooling-of-interests accounting until the passage of specified periods of time
after the effective time of the merger. There are conditions for
pooling-of-interests accounting that address transactions occurring within these
specified periods of time. For example, transactions in Affymetrix or Genetic
MicroSystems common stock by affiliates of Affymetrix and Genetic MicroSystems,
respectively, could prevent the merger from qualifying as a pooling-of-interests
for accounting purposes.



     Because Genetic MicroSystems is not considered a "significant subsidiary"
of Affymetrix for purposes of the Securities and Exchange Commission's
accounting rules, we do not include unaudited pro forma combined financial
statements that give effect to the merger using the pooling-of-interests
accounting method in this document.

                                        9
<PAGE>   17

         UNAUDITED SELECTED PRO FORMA CONDENSED COMBINED FINANCIAL DATA

<TABLE>
<CAPTION>
                                                 YEARS ENDED           SIX MONTHS ENDED
                                                 DECEMBER 31,              JUNE 30,
                                             --------------------    --------------------
                                               1997        1998        1998        1999
                                             --------    --------    --------    --------
                                                (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                          <C>         <C>         <C>         <C>
PRO FORMA CONDENSED COMBINED STATEMENT OF
  OPERATIONS DATA:
Total revenue..............................  $ 19,765    $ 52,413    $ 20,823    $ 44,596
Loss from operations.......................   (28,140)    (32,886)    (15,973)     17,008
Net loss...................................   (22,780)    (26,800)    (13,440)    (14,615)
Preferred Stock dividends..................        --      (2,321)       (695)     (1,626)
Net loss attributable to common
  stockholders.............................   (22,780)    (29,121)    (14,135)    (16,242)
Basic and diluted net loss per common
  share....................................  $  (1.01)   $  (1.23)   $  (0.61)   $  (0.66)
Shares used in computing basic and diluted
  net loss per common share................    22,647      23,636      23,106      24,725
</TABLE>

<TABLE>
<CAPTION>
                                                                JUNE 30, 1999
                                           --------------------------------------------------------
                                                          GENETIC
                                           AFFYMETRIX   MICROSYSTEMS   ADJUSTMENTS         COMBINED
                                           ----------   ------------   -----------         --------
                                                                (IN THOUSANDS)
<S>                                        <C>          <C>            <C>           <C>   <C>
PRO FORMA CONDENSED COMBINED BALANCE
  SHEET DATA:
Cash, cash equivalents and short-term
investments..............................   $ 89,261      $ 2,527        $    --           $ 91,788
Working capital..........................     95,076        3,744         (2,500)    (A)     96,320
Total assets.............................    158,185        6,393             --             64,578
Long-term liabilities, net of current
  portion................................      5,135        3,038             --     (B)      8,173
Convertible redeemable preferred stock...     49,857        3,672         (3,672)    (C)     49,857
Stockholders' equity (deficit)...........     85,113       (2,169)        (2,500)    (A)     80,444
</TABLE>

- -------------------------


(A) Affymetrix and Genetic MicroSystems estimate they will incur direct
    transaction costs of approximately $2.5 million associated with the merger
    for professional fees, financial printing and other related charges. We will
    charge these transaction costs to operations in the quarter in which the
    transaction closes. The pro forma condensed combined balance sheet gives
    effect to these costs as if they had been incurred as of June 30, 1999. We
    do not include the costs in the pro forma condensed combined statement of
    operations data because they are nonrecurring.



    Affymetrix expects to incur additional costs which have not yet been
    determined following the completion of the merger associated with
    integrating the two companies, which costs will be expensed as incurred.



(B) Excludes $150 million of 5% Convertible Subordinated Notes due 2006 that
    Affymetrix issued in September 1999.



(C) The convertible redeemable preferred stock of Genetic MicroSystems will be
    exchanged for shares of Affymetrix common stock upon the completion of the
    merger at the exchange ratio specified in this document.

                                       10
<PAGE>   18

                       COMPARATIVE PER SHARE INFORMATION

     The following table summarizes certain historical financial information and
unaudited pro forma combined and equivalent pro forma financial information on a
per share basis.


     The unaudited pro forma combined financial information assumes that the
merger was completed at the beginning of each of the periods presented and gives
effect to the merger as a pooling-of-interests for accounting purposes. The
basic and diluted unaudited pro forma combined per share information for
Affymetrix is based upon the number of outstanding shares of Affymetrix common
stock adjusted to include the number of Affymetrix common shares that would be
issued in the merger based on the number of shares of Genetic MicroSystems
common and preferred stock outstanding on the dates reported.


     Historical book value per share is computed by dividing stockholders'
equity (deficit) by the number of shares of common stock outstanding at the end
of the period. Affymetrix pro forma combined book value per share is computed by
dividing pro forma combined stockholders' equity by the pro forma number of
shares of Affymetrix common stock outstanding at the end of the period.

     The unaudited equivalent pro forma per share information for Genetic
MicroSystems is based on the unaudited pro forma combined amounts per share for
Affymetrix multiplied by the exchange ratio of 0.2832.

     The information set forth on the next page is qualified in its entirety by
reference to, and should be read in conjunction with, the historical financial
information of Affymetrix incorporated by reference and Genetic MicroSystems
included in this document and the pro forma combined financial information
included in this document.
                                       11
<PAGE>   19

<TABLE>
<CAPTION>
                                                                                SIX MONTHS
                                                   YEARS ENDED DECEMBER 31,       ENDED
                                                  --------------------------     JUNE 30,
                                                   1996      1997      1998        1999
                                                  ------    ------    ------    ----------
<S>                                               <C>       <C>       <C>       <C>
HISTORICAL -- AFFYMETRIX:
Basic and diluted net loss per common share.....  $(0.61)   $(0.99)   $(1.11)     $(0.63)
Book value per common share.....................                                  $ 3.51
Pro forma book value per common share assuming
  conversion of convertible redeemable preferred
  stock in August 1999..........................                                  $ 5.29
</TABLE>

<TABLE>
<CAPTION>
                                                   PERIOD FROM
                                                  AUGUST 7, 1997
                                                     (DATE OF                       SIX MONTHS
                                                  INCEPTION) TO      YEAR ENDED       ENDED
                                                   DECEMBER 31,     DECEMBER 31,     JULY 3,
                                                       1997             1998           1999
                                                  --------------    ------------    ----------
<S>                                               <C>               <C>             <C>
HISTORICAL -- GENETIC MICROSYSTEMS:
Basic and diluted net loss per share............     $(25.38)          $(6.21)        $(1.36)
Book value per common share.....................                                      $(2.15)
</TABLE>

<TABLE>
<CAPTION>
                                                              YEARS ENDED       SIX MONTHS
                                                              DECEMBER 31,        ENDED
                                                            ----------------     JUNE 30,
                                                             1997      1998        1999
                                                            ------    ------    ----------
<S>                                                         <C>       <C>       <C>
AFFYMETRIX PRO FORMA COMBINED:
Basic and diluted net loss per common share...............  $(1.01)   $(1.23)     $(0.66)
Book value per common share...............................                        $ 3.19
Pro forma combined book value per common share assuming
  conversion of Affymetrix convertible redeemable
  preferred stock into common stock in August 1999........                        $ 4.92
GENETIC MICROSYSTEMS EQUIVALENT PRO FORMA COMBINED:
Basic and diluted net loss per common share...............  $(0.29)   $(0.35)     $(0.19)
Book value per common share...............................                        $ 0.90
Equivalent pro forma combined book value per common share
  assuming conversion of Affymetrix convertible preferred
  stock into common stock in August 1999..................                        $ 1.39
</TABLE>

                                       12
<PAGE>   20

                     MARKET PRICE AND DIVIDEND INFORMATION

     Affymetrix common stock has traded on the NASDAQ National Market under the
symbol "AFFX" since Affymetrix' initial public offering on June 6, 1996. There
is no established trading market for any Genetic MicroSystems securities.

     The following table sets forth, for the calendar quarters indicated, the
high and low closing prices per share of Affymetrix common stock as quoted on
the NASDAQ National Market.


<TABLE>
<CAPTION>
                                                           AFFYMETRIX
                                                          COMMON STOCK
                                                        ----------------
                   CALENDAR QUARTER                      HIGH      LOW
                   ----------------                     ------    ------
<S>                                                     <C>       <C>
1996
  Second Quarter (commencing June 6, 1996)............  $17.38    $14.50
  Third Quarter.......................................   17.88     11.25
  Fourth Quarter......................................   22.25     16.25
1997
  First Quarter.......................................   36.38     19.75
  Second Quarter......................................   35.25     20.38
  Third Quarter.......................................   46.75     29.13
  Fourth Quarter......................................   45.00     29.75
1998
  First Quarter.......................................   35.13     24.63
  Second Quarter......................................   34.13     21.13
  Third Quarter.......................................   29.31     16.13
  Fourth Quarter......................................   28.38     19.50
1999
  First Quarter.......................................   41.50     23.75
  Second Quarter......................................   50.25     32.50
  Third Quarter.......................................  127.00     48.00
  Fourth Quarter (through November 15)................  108.00     76.50
</TABLE>


RECENT CLOSING PRICES


     The following table sets forth the closing sales price per share of
Affymetrix common stock on the NASDAQ National Market on September 10, 1999, the
last trading day before public announcement of the merger, and on November 15,
1999, the last practicable trading day prior to the date of this document. Since
there has been no public market for Genetic MicroSystems securities, there is no
information as to the market value of shares of Genetic MicroSystems common or
convertible preferred stock.



<TABLE>
<CAPTION>
                                                             AFFYMETRIX
                                                            COMMON STOCK
                                                            ------------
<S>                                                         <C>
September 10, 1999........................................    $101.13
November 15, 1999.........................................    $ 82.75
</TABLE>


                                       13
<PAGE>   21

     The market price of Affymetrix common stock is likely to fluctuate prior to
the merger. You should obtain current market quotations for Affymetrix common
stock. The future prices or markets for Affymetrix common stock cannot be
predicted.

DIVIDEND INFORMATION


     Neither Affymetrix nor Genetic MicroSystems has ever paid or declared cash
dividends on the shares of its capital stock. Affymetrix does not anticipate
paying cash dividends on its common stock for the foreseeable future.
Affymetrix' present intention is to retain its earnings, if any, for the future
operation and expansion of its business. Any future payment of dividends on
Affymetrix common stock will be at the discretion of the board of directors of
Affymetrix and will depend upon, among other things, Affymetrix' earnings,
financial condition, capital requirements, level of indebtedness and other
factors that the Affymetrix board of directors deems relevant.


NUMBER OF STOCKHOLDERS AND NUMBER OF SHARES OUTSTANDING


     As of November 12, 1999, there were approximately 385 stockholders of
Affymetrix of record who held an aggregate of approximately 25,932,000 shares of
Affymetrix common stock.



     As of November 12, 1999, there were 88 stockholders of Genetic MicroSystems
of record who held an aggregate of approximately 1,006,702 shares of Genetic
MicroSystems common stock and approximately 2,431,977 shares of Genetic
MicroSystems convertible preferred stock.

                                       14
<PAGE>   22

                                  RISK FACTORS


     You should consider the following risk factors in determining how to vote
at the special meeting and in connection with ownership of Affymetrix common
stock.



                          RISKS RELATING TO THE MERGER



BECAUSE THE EXCHANGE RATIO FOR GENETIC MICROSYSTEMS COMMON STOCK IS ESSENTIALLY
FIXED, YOU WILL NOT KNOW THE MARKET VALUE OF THE AFFYMETRIX STOCK YOU WILL
RECEIVE AT THE TIME YOU VOTE ON THE MERGER.



     At the time of the merger, Affymetrix will exchange an aggregate of up to
1,070,000 shares of Affymetrix common stock for all of the Genetic MicroSystems
common and convertible preferred stock outstanding immediately before the merger
and all of the Genetic MicroSystems options or warrants to acquire common and
convertible preferred stock outstanding immediately before the merger.
Affymetrix will not adjust the number of shares issued if there is an increase
or decrease in the market price of Affymetrix common stock. The market price of
Affymetrix common stock is extremely volatile and you should be aware that you
may receive Affymetrix common stock worth more or less than you anticipated. We
cannot assure you that the value of the merger consideration today will be the
same as that on the date of the Genetic MicroSystems special meeting or at the
effective time of the merger.



AFFYMETRIX' BUSINESS COULD SUFFER IF AFFYMETRIX CANNOT INTEGRATE GENETIC
MICROSYSTEMS OR FULLY REALIZE IN A TIMELY FASHION THE COST SAVINGS AND OTHER
BENEFITS IT EXPECTS TO OCCUR AFTER THE MERGER.



     Affymetrix may not be able to integrate successfully and profitably manage
Genetic MicroSystems without incurring substantial costs, delays or other
financial or operational difficulties. There are many things relating to the
integration and management of Genetic MicroSystems that could go wrong and harm
the financial condition of the combined company. Some of these things include:



- - diversion of management's attention;



- - the failure to realize fully in a timely fashion the enhanced cost savings,
  selling opportunities, development, marketing and manufacturing benefits
  Affymetrix expects will occur after the merger; and



- - risks associated with unanticipated events or liabilities.



     Although Affymetrix has conducted what it believes to be a prudent level of
review regarding the operational condition of Genetic MicroSystems, it cannot
predict the full range of integration-related problems which may occur.



                 RISKS RELATING TO AFFYMETRIX AND ITS BUSINESS



BECAUSE AFFYMETRIX COMMON STOCK IS EXTREMELY VOLATILE AND DIFFICULT TO PREDICT,
BASED IN PART UPON THE VARIABILITY IN AFFYMETRIX' QUARTERLY RESULTS OF
OPERATION, THE MARKET VALUE OF YOUR AFFYMETRIX COMMON STOCK WILL FLUCTUATE
SIGNIFICANTLY AND MAY DECREASE.


     Recently, the stock market and the trading price for Affymetrix common
stock have experienced significant price fluctuations. Market fluctuations may
reduce the market price of Affymetrix common stock. As a result of any one of
the following factors, some of which are beyond Affymetrix' control, the market
value of the Affymetrix common stock you receive as a result of the merger may
be significantly less than the market value of Affymetrix common stock today:

- - quarterly variations in Affymetrix' operating results;


- - the sale by Affymetrix' principal stockholder, Glaxo Wellcome, plc and its
  affiliates, of all or a portion of their 31% interest;


                                       15
<PAGE>   23


- - The simultaneous sale by a significant number of former Genetic MicroSystems
  stockholders of Affymetrix common stock shortly after the merger;


- - announcements of new commercial products and initiatives either by Affymetrix
  or its collaborative partners or competitors;

- - developments in litigation initiated against Affymetrix or by Affymetrix;

- - developments concerning proprietary rights;

- - technological innovations by Affymetrix and its competitors;

- - new collaborative agreements;

- - announcements of Affymetrix' results of research activities;

- - changes in patent laws;

- - changes in government regulation or new regulatory actions; and


- - fluctuations in the stock market price and volume of traded shares generally,
  especially fluctuations in the traditionally volatile technology and
  biotechnology sectors.



     One important reason for Affymetrix' volatile stock price is the volatility
in its quarterly results of operation, which may fluctuate significantly
period-to-period. These fluctuations depend on a number of factors, including:



- - the volume and timing of orders for GeneChip products;



- - the timing of probe array, instrument and software shipments and
  installations;



- - Affymetrix' manufacturing capabilities;



- - variations in product yields and gross margins;



- - variations in revenue recognized under Affymetrix' supply and collaborative
  agreements, including license fees, product sales, design fees, milestones,
  royalties and other contract revenues;



- - Affymetrix' mix of products sold;



- - the timing of new product introductions by Affymetrix;



- - variations in expenses incurred in connection with the operations of
  Affymetrix' business, including legal fees, manufacturing facility start-up
  costs and capital expenditures;



- - the delay by customers of fourth quarter 1999 orders until after January 1,
  2000;



- - the introduction of new products by Affymetrix' competitors;



- - the cost and availability of licenses to third party intellectual property
  associated with Affymetrix' products;



- - market acceptance of the GeneChip products and other potential products;



- - the cost, quality and availability of reagents and components required to
  manufacture or use Affymetrix' products;



- - the price and terms under which Affymetrix is able to license its intellectual
  property to others;



- - changes in commercial and government funding of research using Affymetrix'
  products;


                                       16
<PAGE>   24


- - regulatory actions; and



- - third-party reimbursement policies.



     Although Affymetrix believes that period-to-period comparisons of
Affymetrix' results of operations are not a good indication of Affymetrix'
future performance, it is likely that in some future quarter or quarters,
Affymetrix' operating results will be below the expectations of public market
analysts or investors and the market price of Affymetrix common stock may fall
significantly.



BECAUSE AFFYMETRIX HAS A LIMITED OPERATING HISTORY AND IS IN THE EARLY STAGES OF
DEVELOPMENT OF COMMERCIAL USES FOR ITS TECHNOLOGY, AFFYMETRIX CANNOT ASSURE YOU
THAT IT WILL EVENTUALLY DEVELOP A COMMERCIALLY SUCCESSFUL PRODUCT.



     For the most part, Affymetrix' technologies are still in the early stages
of development and Affymetrix has just begun to incorporate its technologies
into commercial products. Affymetrix needs to make significant investments to
ensure Affymetrix' products perform correctly and are cost-effective as well as
to obtain additional regulatory approvals to sell its product for purposes other
than research use. Even if Affymetrix develops its products for commercial use
and obtains all necessary regulatory approval, it may not be able to develop
products that:



- - are accepted by the research, diagnostic or other marketplaces;



- - are accurate and effective;



- - meet applicable regulatory standards in a timely manner;



- - are protected from competition by others;



- - do not infringe the intellectual proprietary rights of others;



- - can be manufactured in sufficient quantities or at a reasonable cost; or



- - can be marketed successfully.



UNLESS AFFYMETRIX DECREASES VARIABILITY IN ITS MANUFACTURING YIELDS, INCREASES
ITS MANUFACTURING CAPACITY AND RESOLVES ITS OTHER MANUFACTURING PROBLEMS, IT MAY
BE UNABLE TO MANUFACTURE PRODUCTS CONSISTENTLY ON A TIMELY BASIS THAT MEET
CUSTOMER PERFORMANCE EXPECTATIONS WHICH COULD HARM ITS RELATIONSHIP WITH ITS
CUSTOMERS AND CAUSE DEMAND FOR ITS PRODUCTS TO DECLINE AND HARM ITS FINANCIAL
PERFORMANCE.



     Affymetrix is currently manufacturing limited quantities of probe arrays
for internal and collaborative purposes and for sale to the research market in
two manufacturing facilities, one located in Sunnyvale, California and the other
in West Sacramento, California. The actual number of probe arrays Affymetrix is
able to sell or use depends on the utilization of the production capacity at
these facilities, the yield of probe arrays that pass quality control testing
and the number of probe arrays manufactured on each probe array wafer. Portions
of the production capacity at these facilities are also limited to only some
types of probe arrays. Affymetrix has experienced and continues to experience
significant variability in the manufacturing yield of its GeneChip products
which has reduced, and is expected to continue to reduce, its gross margins and
business. Affymetrix has also experienced, and anticipates that it will continue
to experience, difficulties in meeting anticipated customer, collaborator and
internal demand for some of its probe array products. Affymetrix' inability to
deliver products in a timely manner could seriously harm its relationship with
its customers, delay introduction of new products and cause demand for its
products to decline.



     Because Affymetrix has a limited manufacturing history, it does not fully
understand all of the factors that affect its manufacturing processes, which may
not easily allow for production in larger volumes. As a result, manufacturing
and quality control problems have arisen and Affymetrix expects them to continue
to arise as Affymetrix attempts to increase the production rate at its
manufacturing facilities. Affymetrix may not be able to increase production
rates at these facilities in a timely and cost-effective manner or at
commercially reasonable cost.



     Moreover, the Sunnyvale, California manufacturing facility is located in an
earthquake-prone area and the West Sacramento facility is


                                       17
<PAGE>   25


susceptible to flooding. Although Affymetrix has two manufacturing facilities,
which Affymetrix expects will mitigate risk when the West Sacramento facility
becomes fully operational and capacity is increased at that facility, Affymetrix
could be unable to manufacture products for sale or its capacity could be
significantly decreased if one of these facilities is damaged until that damaged
facility is replaced or restored to operation.



BECAUSE AFFYMETRIX' QUALITY CONTROL PROCEDURES MAY NOT BE FULLY DEVELOPED TO
ENSURE PROPER PERFORMANCE OF ITS PRODUCTS, AFFYMETRIX' CUSTOMERS MAY RECEIVE
UNDERPERFORMING PRODUCTS AND MAY DECIDE TO SWITCH TO A NEW SUPPLIER.



     The GeneChip products are produced in an innovative and complicated
manufacturing process. Unlike semiconductor companies, Affymetrix can test only
a portion of the products it produces due to the unique nature of its products.
It is possible that Affymetrix may not identify a probe array that does not meet
all of Affymetrix' performance specifications before it is shipped. Further,
after the probe arrays are shipped, a customer may test only selected probes.
Due to the complexity and limited operating history of these products,
Affymetrix and its customers have experienced technical problems and anticipate
that additional technical problems will occur and be discovered as more GeneChip
systems are placed into operation. If Affymetrix is unable to deliver products
consistently to its customers that meet their performance expectations, demand
for Affymetrix' products will decline.



IF AFFYMETRIX FAILS TO OBTAIN, ENFORCE, DEFEND OR MAINTAIN ITS INTELLECTUAL
PROPERTY RIGHTS, OR IF IT NEEDS A LICENSE TO INTELLECTUAL PROPERTY TO CONTINUE
ITS BUSINESS, ITS BUSINESS MAY BE IRREPARABLY HARMED.



     Affymetrix is involved in significant litigation in which third parties
assert that Affymetrix is infringing their intellectual property. In addition,
other parties have patents that Affymetrix believes may be asserted against
Affymetrix.



     If Affymetrix, its partners or its customers must obtain a license to
continue to manufacture, market or use its current or future products and
processes, Affymetrix, its partners or its customers may not be able to obtain
that license on commercially acceptable terms, if at all. For example, if Hyseq
or Oxford Gene Technology were successful in their law suits against Affymetrix,
Affymetrix believes neither company would grant Affymetrix a license on
commercially reasonable terms, if at all. Affymetrix may also have to negotiate
a license with third parties, either because it believes it may be infringing
another party's intellectual property or because it wishes to expand its product
line using another party's technology. Affymetrix may not be able to obtain
these licenses on commercially acceptable terms, if at all.



     Affymetrix' failure to enforce successfully its intellectual property
rights would remove a legal obstacle to competitors in designing probe array
systems with similar competitive advantages to Affymetrix' GeneChip technology.
Affymetrix is currently involved in significant litigation and/or oppositions
with Hyseq, Oxford Gene Technology, Incyte, Synteni, Multilyte and ProtoGene
concerning Affymetrix' intellectual property which consume and will continue to
consume substantial financial and managerial resources. Further, because of the
substantial amount of discovery required in connection with any litigation,
there is a risk that disclosure could compromise confidential information. In
addition, patent law relating to the scope of claims in Affymetrix' technology
fields is still evolving and the extent of future protection for Affymetrix'
proprietary rights is uncertain.



     The patent positions of pharmaceutical and biotechnology companies are
generally uncertain and involve complex legal and factual questions. Affymetrix
believes that there will continue to be significant litigation in the industry
regarding patent and other intellectual property rights. As a result, Affymetrix
cannot guarantee:



- - that any of Affymetrix' pending patent applications will result in issued
  patents;


                                       18
<PAGE>   26


- - that Affymetrix will develop additional technologies that are patentable;



- - that any patents issued to Affymetrix or its strategic partners will provide a
  basis for commercially viable products;



- - that third parties will not challenge any patents issued to Affymetrix or its
  strategic partners;



- - that any patents issued to Affymetrix or its strategic partners will not be
  challenged by third parties; or



- - that the patents of others will not have a negative impact on Affymetrix'
  ability to do business.



     Others may independently develop similar or alternative technologies,
duplicate any of Affymetrix' technologies, or design around or invalidate
Affymetrix' patented technologies. In addition, Affymetrix has incurred and
expects to continue to incur substantial costs to bring litigation and to defend
against the patent suits brought by third parties. Administrative proceedings,
such as oppositions or interferences, in both the United States Patent Office or
any foreign patent office could also substantially reduce the scope of
Affymetrix' patent protection as well as result in the expenditure of
substantial funds in legal fees.



BECAUSE THE MARKETS IN WHICH AFFYMETRIX OPERATES ARE HIGHLY COMPETITIVE AND
RAPIDLY CHANGING, AFFYMETRIX MUST CONTINUE TO DEVELOP AND INTRODUCE NEW PRODUCTS
TO COMPETE SUCCESSFULLY AGAINST NEW ENTRANTS AND ESTABLISHED COMPANIES WITH
GREATER RESOURCES.



     Affymetrix competes in markets that are new, intensely competitive, highly
fragmented and rapidly changing. Affymetrix has experienced and expects to
continue to experience increased competition from current and potential
competitors, many of which have significantly greater financial, technical,
marketing and other resources.



     A large number of publicly traded and privately held companies including
Applied Biosystems division of Perkin-Elmer, Amersham Pharmacia Biotech,
CuraGen, Gene Logic, General Scanning, Corning, Genome Solutions,
Hewlett-Packard, Hitachi, Incyte/ Synteni, Illumina, Lynx and Motorola also are
developing or have developed DNA probe based tests or other products and
services, some of which may be competitive with Affymetrix' products.



     The failure of Affymetrix to develop the enhancements to its technology or
manufacturing equipment necessary to compete successfully with newly emerging
technologies, or to develop products based on these technologies will harm
Affymetrix' business.



     Currently, Affymetrix' principal competition comes from existing DNA probe
array and other technologies that are used to perform many of the same functions
for which Affymetrix markets its GeneChip products. In order to compete against
existing and newly developed technologies and maintain pricing and gross
margins, Affymetrix will need to be successful in demonstrating to potential
customers that the GeneChip products provide improved performance and
capabilities and in asserting Affymetrix patents in the DNA probe array field.



     Affymetrix' competitors may be able to respond more quickly to new or
emerging technologies and changes in customer requirements than Affymetrix can.
In addition, current and potential competitors have greater name recognition,
more extensive customer bases and access to proprietary genetic content.



BECAUSE AFFYMETRIX DEPENDS ON A LIMITED NUMBER OF SUPPLIERS, IT MAY NOT BE ABLE
TO SHIP PRODUCTS ON TIME IF IT IS UNABLE TO OBTAIN AN ADEQUATE SUPPLY OF
MANUFACTURING EQUIPMENT, RAW MATERIALS AND PRODUCT COMPONENTS FROM THOSE
SUPPLIERS ON A TIMELY BASIS, WHICH COULD REDUCE DEMAND FOR ITS PRODUCTS.



     Affymetrix relies on Hewlett-Packard to manufacture, install and service
its scanners and on Enzo to manufacture certain reagents used with probe arrays
and various labeling kits needed to process samples. Key parts of the GeneChip
product line, as well as various equipment and raw materials used in the
synthesis of probe arrays, are currently available only from a single source or
a limited number


                                       19
<PAGE>   27


of sources. In addition, components of Affymetrix' manufacturing equipment are
available from one of only a few suppliers. Affymetrix cannot assure you that
manufacturing equipment, scanners or other components of the GeneChip product
will be available in a timely fashion and in sufficient quantities under
acceptable terms. Even if alternative sources of supply are available, it could
be time consuming and expensive for Affymetrix to qualify new vendors. In
addition, Affymetrix is dependent on its vendors to provide components of
appropriate quality and reliability and to meet applicable regulatory
requirements. Consequently, in the event that supplies from these vendors were
delayed or interrupted for any reason, Affymetrix could be delayed in its
ability to develop and deliver products to its customers.



IF AFFYMETRIX IS UNABLE TO MAINTAIN ITS RELATIONSHIPS WITH COLLABORATIVE
PARTNERS, AFFYMETRIX MAY HAVE DIFFICULTY SELLING ITS PRODUCTS AND SERVICES.



     Affymetrix believes that its success in penetrating its target markets
depends in part on Affymetrix' ability to develop and maintain collaborative
relationships with key pharmaceutical, diagnostic, biotechnology,
bioinformatics, analytical instrument and reagent companies as well as with
academic researchers, all in an effort to help develop, test, manufacture, sell
and service Affymetrix' GeneChip technology. Affymetrix has significant
relationships with Hewlett-Packard, bioMerieux, Amersham Pharmacia Biotech KK
and Roche Molecular Systems and Affymetrix has entered into a consortium with
the Whitehead Institute, Millennium Pharmaceuticals and Bristol-Myers Squibb.
Affymetrix has received a material portion of its revenue since inception from
these and other collaborative partners. Affymetrix also intends to enter into
collaborative arrangements with other companies to expand Affymetrix'
operations, apply its technology, and sell potential future products.
Affymetrix' present or future collaborative partners may not be able to perform
their obligations as expected or devote sufficient resources to the development,
clinical testing, supply or marketing of Affymetrix' potential products
developed under these collaborations. Moreover, any of the following
developments could impact Affymetrix' business, financial condition and results
of operations:



- - one of Affymetrix' partners develops technologies or components competitive
  with Affymetrix' GeneChip products;



- - Affymetrix' existing collaborations preclude it from entering into additional
  arrangements;



- - failure of Affymetrix' partners to obtain timely regulatory approvals;



- - premature termination of an agreement;



- - one of Affymetrix' partners' failure to devote sufficient resources to the
  development and sale of its products; or



- - inability of one of Affymetrix' partners to supply products to it.



     In addition, Affymetrix' agreements with its collaborators may have
provisions that allow for termination or give rise to disputes regarding the
rights and obligations of the parties. These and other possible disagreements
could lead to termination of the agreement or delays in collaborative research,
development, supply or commercialization of certain products, or could require
or result in litigation or arbitration. Any such delay, litigation or
arbitration could impact Affymetrix' financial condition. Any of Affymetrix'
collaborations may prove to be unsuccessful. Likewise, Affymetrix may not be
able to negotiate future collaborative arrangements on acceptable terms, if at
all.



UNLESS AFFYMETRIX DEVELOPS AND MARKETS PROFITABLE COMMERCIAL PRODUCTS, IT WILL
CONTINUE TO EXPERIENCE SIGNIFICANT OPERATING LOSSES.



     Affymetrix has experienced operating losses of $12 million to $23 million
per year since its inception and has an accumulated deficit of approximately
$107.6 million as of June 30, 1999. Moreover, Affymetrix expects to incur
substantial additional operating losses as a result of increases in expenses for
manufacturing, marketing and sales, research and product development and general
and administrative costs. If Affymetrix is unable to achieve, among


                                       20
<PAGE>   28


other things, the goals set forth below, it may never achieve profitability:



- - achieve consistently acceptable manufacturing yields;



- - develop products that the marketplace accepts;



- - create a product mix that is appealing to pharmaceutical and biotechnology
  companies, academic research centers and clinical reference laboratories;



- - enter into supply agreements with customers desiring to use Affymetrix'
  products;



- - establish its commercial manufacturing capability for DNA probe arrays;



- - cost-effectively manufacture components of its GeneChip product line;



- - avoid infringing on the intellectual property rights of others;



- - enforce Affymetrix' intellectual property rights against others;



- - establish sales and distribution capabilities cost-effectively;



- - develop its marketing capabilities cost-effectively;



- - obtain necessary regulatory approvals; and



- - hire and retain qualified key personnel.



AFFYMETRIX HAS LIMITED SALES, MARKETING AND TECHNICAL SUPPORT EXPERIENCE, WHICH
MAY HURT ITS EFFORTS AT SELLING ITS PRODUCTS.



     Affymetrix has expanded the distribution of its products in recent years.
This expansion has placed new and increased demands on its direct sales force
and technical and sales support staff, including accounting controls. Although
Affymetrix invests significant resources to expand its direct sales force and
its technical and support staff, only a limited number of qualified personnel
are available in these areas. Therefore, Affymetrix may not be able to expand
its direct sales force and technical support staff as necessary to support its
growing operations. Affymetrix has also entered into a non-exclusive
distribution agreement with Amersham Pharmacia Biotech KK covering Japan and a
service agreement with Hewlett-Packard for its GeneArray scanner. Affymetrix'
existing organization and relationships may not be sufficient and Affymetrix may
have to expand its organization and enter into additional collaboration or
distribution arrangements to sell its products both inside and outside the
United States. Affymetrix cannot assure you that:



- - Affymetrix will be able to establish a sufficiently sized sales, marketing or
  technical support organization;



- - Amersham Pharmacia Biotech KK will be successful in distributing Affymetrix'
  products;



- - Amersham Pharmacia Biotech KK will not sell competitive products in Japan;



- - Hewlett-Packard will be successful in servicing Affymetrix' instruments and
  not become its competitor; or



- - Affymetrix will be able to establish additional collaborative or distribution
  arrangements to sell, market and service its products.



THE LOSS OF A KEY CUSTOMER COULD SUBSTANTIALLY REDUCE AFFYMETRIX' REVENUES AND
BE PERCEIVED AS A LOSS OF MOMENTUM IN ITS BUSINESS.



     Affymetrix believes that the sales cycle for the GeneChip products will be
lengthy due to the need to educate potential customers about its
characteristics. As a result, Affymetrix' customers are concentrated in a small
number of pharmaceutical and biotechnology companies, academic research centers
and clinical reference laboratories. Affymetrix expects that a small number of
customers will continue to account for a substantial portion of revenues for the
foreseeable future. If Affymetrix loses a major customer, Affymetrix' revenues
may be substantially reduced and investors may perceive this as a loss of
momentum in Affymetrix' business. Moreover, if consolidation in the
pharmaceutical and biotechnology industries continues, Affymetrix' current and
potential customers could decrease or slow aggregate sales of its technology and
shrink its target market.



     Affymetrix' dependence on sales to a few customers may also strengthen the
negotiating


                                       21
<PAGE>   29


position of its potential customers, which, in turn, could reduce the sales
price of the GeneChip products and reduce Affymetrix' revenues.



BECAUSE AFFYMETRIX' BUSINESS IS HIGHLY DEPENDANT ON KEY EXECUTIVES AND
SCIENTISTS, AFFYMETRIX' INABILITY TO RECRUIT AND RETAIN THESE PERSONNEL COULD
HINDER ITS BUSINESS EXPANSION PLANS.



     Affymetrix is highly dependent on its executive officers and its senior
scientists and engineers, including its scientific advisors. The loss of
services of any of these persons could have a negative impact on Affymetrix'
product development and marketing efforts. In addition, research, product
development and sales will require additional skilled personnel in areas such as
bioinformatics, organic chemistry, information services, regulatory affairs,
manufacturing, sales, marketing and technical support.



     There is a shortage of skilled personnel, which is likely to continue for
some time. As a result, competition for these people, particularly for employees
with technical expertise, is intense and the turnover rate for these people is
high. If Affymetrix is unable to hire, train and retain a sufficient number of
qualified employees, it could hinder the planned expansion of its business.



     In addition, Affymetrix relies on its scientific advisors and consultants
to assist it in formulating its research, development and commercialization
strategy. All of the scientific advisors and consultants are engaged by
employers other than Affymetrix and have commitments to other entities that may
limit their availability to Affymetrix. Some of Affymetrix' scientific advisors
and consultants also consult for companies that may be its competitors.



SERIOUS ETHICAL, LEGAL AND SOCIAL IMPLICATIONS SURROUNDING GENETIC TESTING MAY
HARM THE MARKET ACCEPTANCE OF AFFYMETRIX' PRODUCTS OR MAY CAUSE GOVERNMENTAL
AUTHORITIES TO SEVERELY RESTRICT THE USE OF GENETIC TESTS, WHICH COULD SERIOUSLY
REDUCE THE MARKET FOR AFFYMETRIX' PRODUCTS.


     The genetic tests under development by Affymetrix have given rise to some
difficult issues, including:

- - genetic tests may be subject to ethical concerns or reluctance to administer
  or pay for tests for conditions that are not treatable; and

- - specific gene-based diagnostic tests could encounter public resistance,
  resulting in societal and governmental concerns regarding genetic testing in
  general.

     The prospect of broadly available genetic testing has also raised issues
regarding the appropriate utilization and the confidentiality of information
provided by this testing.

     Governmental authorities could limit the use of genetic testing or prohibit
it under some conditions. These restrictions would reduce the market for
Affymetrix' products. Moreover, ethical concerns about genetic testing may
seriously affect market acceptance of Affymetrix' GeneChip product or result in
legislative restrictions on the use of Affymetrix' products in some countries.


REDUCTIONS IN GOVERNMENT FUNDING OF RESEARCH INSTITUTIONS COULD REDUCE
AFFYMETRIX' REVENUES.



     Affymetrix sells a significant portion of its products for research use to
universities, government research laboratories, private foundations and other
institutions whose funding is dependent upon grants from government agencies,
such as the National Institute of Health. The government, however, may
significantly reduce research funding in the future. Any such reduction may harm
Affymetrix' existing and prospective research customers' ability to purchase
Affymetrix' products for research use.



IF AFFYMETRIX CANNOT COMPLY WITH GOVERNMENT REGULATIONS OR AFFYMETRIX
EXPERIENCES DELAYS IN GETTING APPROVAL FROM GOVERNMENTAL AGENCIES OR
GOVERNMENTAL AGENCIES RESTRICT AFFYMETRIX' ABILITY TO MARKET ITS PRODUCTS,
AFFYMETRIX WILL BE UNABLE TO SELL A COMMERCIAL PRODUCT.



     Affymetrix must comply with the FDA's regulations for the sale of
"analyte-specific reagents," as well as other standards prescribed


                                       22
<PAGE>   30


by various federal, state and local regulatory agencies in the United States and
other countries. Although Affymetrix has registered the manufacturing sites for
its arrays as ASRs with the FDA and its products are listed with the FDA,
Affymetrix cannot guarantee that it will be able to comply with the regulations
at reasonable costs.



     In addition, many of Affymetrix' future products, including its diagnostic
products, will be regulated as medical devices when Affymetrix or its partners
begins selling its products commercially for non-research uses and will be
subject to further approval by the FDA or foreign agencies and compliance with
the ISO quality standards instituted by the International Organization for
Standardization for sales in Europe. Affymetrix, however, has not filed any
applications to market commercially its products as medical devices with the FDA
or any foreign agency. Delays in the application or approval process may cause
Affymetrix to introduce its products into the market later than anticipated. Any
failure to obtain regulatory approval, restrictions on Affymetrix' ability to
market its products, or delays in the introduction of Affymetrix' products to
the market could harm its business.



     Moreover, the FDA and state agencies inspect medical device manufacturers
periodically. If the FDA believes that a company is not in compliance with
applicable laws or regulations, it can take any number of actions, including
detaining or seizing products and assessing civil and criminal penalties against
Affymetrix, its officers or its employees.



     Medical device laws and regulations are also in effect in many of the
countries where Affymetrix may do business. These laws and regulations range
from comprehensive device approval requirements for some or all of Affymetrix'
medical device products to requests for product data or certifications. The
number and scope of these requirements are increasing. Affymetrix may not be
able to obtain regulatory approvals in these countries or it may be required to
incur significant costs in obtaining or maintaining its foreign regulatory
approvals. In addition, the export of certain of Affymetrix' products which have
not yet been cleared for domestic commercial distribution may be subject to FDA
export restrictions. Any failure to obtain product approvals in a timely fashion
or to comply with state or foreign medical device laws and regulations may
prevent Affymetrix from marketing its products.



     Affymetrix is also subject to numerous environmental and safety laws and
regulations, including those governing the use, storage and disposal of
hazardous and biological materials, and construction of new facilities.
Affymetrix may not be able to obtain the necessary permits to operate new
facilities or the cost of compliance may be very high.



AFFYMETRIX' BUSINESS COULD BE HARMED IF AFFYMETRIX' PRODUCTS OR THE PRODUCTS
UPON WHICH IT DEPENDS MALFUNCTION OR BECOME UNAVAILABLE BECAUSE OF YEAR 2000
PROBLEMS.



     Affymetrix is continuing to assess or has assessed the potential impact of
the year 2000 computer problem on its products, including GeneChip products and
software, information systems, embedded systems, including computers used in its
manufacturing process, and on the ability of some third parties to supply
critical materials and services as well as the readiness of some customers.
Affymetrix completed the assessment of its products, computer systems, embedded
systems, some third party suppliers and major customers in the second quarter of
1999, and plans to take necessary remediation action by the end of 1999. While
Affymetrix does not anticipate a material business interruption to result from
the year 2000 problem, Affymetrix may experience a business interruption if any
of Affymetrix' products, information systems, embedded systems, key third party
suppliers and services providers and major customers are not year 2000 ready. In
addition, Affymetrix' sales in the last quarter of 1999 may be reduced if
customers defer purchases due to year 2000 concerns. Affymetrix has implemented
a year 2000 contingency plan that involves purchasing and building inventory
over the remainder of 1999 so that it will be able to continue to operate in the
event of a modest and short-term


                                       23
<PAGE>   31


supply shortage resulting from any year 2000 problems experienced by its
suppliers.



AFFYMETRIX' EFFORTS TO INCREASE ITS PRESENCE IN MARKETS OUTSIDE OF THE UNITED
STATES MAY BE UNSUCCESSFUL AND COULD RESULT IN LOSSES.



     Affymetrix intends to expand its international presence in order to
increase its export sales. Export sales to international customers entail a
number of risks, each of which could reduce Affymetrix' revenues. These risks
include:



- - unexpected changes in, or impositions of, legislative or regulatory
  requirements;



- - delays resulting from difficulty in obtaining export licenses for certain
  technology, tariffs, quotas and other trade barriers and restrictions;



- - longer payment cycles and greater difficulty in accounts receivable
  collection;



- - potentially adverse taxes;



- - currency exchange fluctuations;



- - the burdens of complying with a variety of foreign laws; and



- - other factors beyond Affymetrix' control.



RESTRICTIVE REIMBURSEMENT POLICIES BY HEALTH CARE ORGANIZATIONS COULD REDUCE
AFFYMETRIX' REVENUES.



     Affymetrix' ability to sell certain products and services successfully may
depend on the extent to which Affymetrix is able to secure reimbursement from
government authorities, such as Medicare and Medicaid, private health insurers,
and other organizations, such as health maintenance organizations. These
third-party payors are increasingly likely to challenge the prices charged for
health care products and services. The cumulative effect of the trend towards
managed health care in the United States, legislative proposals to reform health
care or reduce government insurance programs, and the concurrent growth of
organizations such as HMOs, which could control or significantly influence the
purchase of health care products and services, may result in lower prices for
health care products and services sold by Affymetrix, its customers and its
collaborative partners. This reduction in turn could reduce the amount of
Affymetrix' future revenues or royalty payments that may be due to it. The lower
prices could also harm Affymetrix' profits and the profits of its customers and
collaborative partners. As a result, pharmaceutical, diagnostic and
biotechnology companies may choose to reduce or eliminate certain research and
development programs that utilize Affymetrix' products. A reduction of
Affymetrix' revenues or royalty payments or the reduction or cancellation of
research programs that utilize Affymetrix' products could seriously harm its
business, financial condition and results of operations.



BECAUSE GLAXO WELLCOME OWNS A SUBSTANTIAL PORTION OF AFFYMETRIX' OUTSTANDING
CAPITAL STOCK, IT MAY BE ABLE TO INFLUENCE THE OUTCOME OF STOCKHOLDER VOTES.



     Glaxo Wellcome, plc and its affiliates currently beneficially own
approximately 31% of the outstanding Affymetrix common stock. Although
Affymetrix has executed a governance agreement with Glaxo, Glaxo nevertheless
may be able to influence the outcome of stockholder votes, including votes
concerning the election of directors, adoption of amendments to Affymetrix'
certificate of incorporation and bylaws and approval of mergers and other
significant corporate transactions.



AFFYMETRIX HAS VARIOUS MECHANISMS IN PLACE TO DISCOURAGE TAKEOVER ATTEMPTS WHICH
MAY DISCOURAGE, DELAY OR PREVENT A CHANGE IN CONTROL THAT A STOCKHOLDER MAY
CONSIDER FAVORABLE.



     Affymetrix adopted a stockholder rights plan and change of control policy.
The purpose of the stockholder rights plan is to allow Affymetrix and its board
of directors an opportunity to deal responsibly with parties that attempt to
gain a control position in Affymetrix without the approval of the board of
directors. The purpose of the change of control policy is to ensure that
Affymetrix' employees are treated fairly in the event of a change of control.
Affymetrix' stockholder rights plan and change of control policy may discourage,
delay or prevent a change in control of Affymetrix that a stockholder may
consider favorable.


     In addition, certain provisions of Affymetrix' certificate of incorporation
and bylaws may

                                       24
<PAGE>   32

discourage, delay or prevent a change in control
of it that a stockholder may consider favorable. These provisions include:

- - authorizing the issuance of "blank check" preferred stock;

- - prohibiting cumulative voting in the election of directors;

- - requiring super-majority voting to effect certain amendments to Affymetrix'
  certificate of incorporation and bylaws;

- - limiting the persons who may call special meetings of stockholders;

- - prohibiting stockholder action by written consent; and

- - establishing advance notice requirements for nominations for election to the
  board of directors or for proposing matters that can be acted upon by
  stockholders at stockholder meetings.


     In addition, relevant provisions of Delaware law and Affymetrix' stock
incentive plans may also discourage, delay or prevent a change in control.



IF AFFYMETRIX IS FOUND LIABLE FOR A PRODUCT LIABILITY CLAIM, IT MAY NOT HAVE
ADEQUATE INSURANCE TO PAY THAT CLAIM, WHICH WILL HARM AFFYMETRIX' FINANCIAL
CONDITION.



     Affymetrix' business exposes it to potential product liability claims that
are inherent in the testing, manufacturing, marketing and sale of human
diagnostic and therapeutic products. Affymetrix intends to acquire additional
insurance, should it be desirable, for clinical liability risks. Affymetrix may
not be able to obtain this insurance or general product liability insurance on
acceptable terms or at reasonable costs or this insurance may not be in
sufficient amounts to provide adequate coverage against potential liabilities.



BECAUSE THE MARKET PRICE OF AFFYMETRIX COMMON STOCK IS EXTREMELY VOLATILE,
AFFYMETRIX MAY BE AT RISK OF SECURITIES CLASS ACTION LITIGATION.



     In the past, securities class action litigation has often been brought
against a company following periods of volatility in the market price of its
securities. Due to the potential volatility of its stock price, Affymetrix may
be the target of this type of litigation in the future. Securities litigation
could result in substantial costs and divert management's attention and
resources.


                                       25
<PAGE>   33

                        CAUTIONARY STATEMENT CONCERNING
                           FORWARD-LOOKING STATEMENTS

     In addition to historical information, this document and, in the case of
Affymetrix, the documents incorporated by reference in this document, contain
forward-looking statements concerning Affymetrix and Genetic MicroSystems. These
statements relate to future events or Affymetrix' or Genetic MicroSystems'
future financial performance. In some cases, you can identify forward-looking
statements by language such as "may," "will," "should," "expects,"
"anticipates," "believes," "estimates," "predicts," "potential" or "continue" or
the negative of such terms or other similar expressions. These statements are
only predictions and involve known and unknown risks, uncertainties and other
factors, including the risks outlined under "Risk Factors" that may cause
Affymetrix', Genetic MicroSystems', or Affymetrix' and Genetic MicroSystems'
industry's actual results, levels of activity, performance or achievements to
differ from results, levels of activity, performance or achievements expressed
or implied by these forward-looking statements. You should carefully consider
the risks described in the "Risk Factors" section, in addition to the other
information set forth in this document and the documents incorporated by
reference in this document.


     Although Affymetrix and Genetic MicroSystems believe that the expectations
reflected in the forward-looking statements are reasonable, Affymetrix and
Genetic MicroSystems cannot guarantee future results, levels of activity,
performance or achievements. Moreover, none of Affymetrix, Genetic MicroSystems
or any other person assumes responsibility for the accuracy and completeness of
those statements. Affymetrix and Genetic MicroSystems are under no duty to
update any of the forward-looking statements after the date of this document to
conform such statements to actual results. Affymetrix claims the protection of
the safe harbor for forward-looking statements contained in the Private
Securities Litigation Reform Act of 1995.




                                       26
<PAGE>   34


                    THE GENETIC MICROSYSTEMS SPECIAL MEETING


GENERAL; DATE, PLACE AND TIME


     We are providing this document to holders of Genetic MicroSystems stock in
connection with the solicitation of proxies by the Genetic MicroSystems board of
directors for use at the special meeting of stockholders of Genetic MicroSystems
to be held on --, 1999, at 10:00 a.m. local time, at the offices of Genetic
MicroSystems located at 34 Commerce Way, Woburn, Massachusetts 01801, and at any
adjournment or postponement of the meeting.


MATTERS TO BE CONSIDERED


     At the special meeting, Genetic MicroSystems will ask its stockholders to
consider and vote upon the following:


     - a proposal to adopt the merger agreement;

     - the appointment of Jean Montagu as Stockholder Representative under the
       merger agreement and the escrow agreement; and


     - other matters as may properly be brought before the special meeting or
       any adjournment or postponement of the meeting.



     In addition, at the special meeting, holders of Genetic MicroSystems Series
A convertible preferred stock will vote on whether or not to treat the merger as
a liquidation or dissolution of Genetic MicroSystems.



RECORD DATE


     The board of directors of Genetic MicroSystems fixed the close of business
on --,1999 as the record date for the special meeting. Accordingly, only holders
of Genetic MicroSystems capital stock of record at the close of business on --,
1999, will be entitled to notice of, and to vote at, the special meeting.

STOCKHOLDERS ENTITLED TO VOTE


     As of the close of business on the record date, there were 1,006,702 shares
of common stock, 2,000,000 shares of Series A convertible preferred stock and
431,977 shares of Series B convertible preferred stock of Genetic MicroSystems
outstanding and entitled to vote. The holders of common stock are entitled to
cast one vote for each share of common stock they hold on each matter submitted
to the common stockholders for a vote at the special meeting. The holders of
Series A convertible preferred stock and Series B convertible preferred stock
are entitled to cast one vote for each share of common stock into which their
Series A convertible preferred stock or Series B convertible preferred stock, as
the case may be, could then be converted on each matter submitted to a vote at
the special meeting. However, at the special meeting, only holders of Genetic
MicroSystems Series A convertible preferred stock will be entitled to vote on
the proposal that the merger does not constitute a liquidation or dissolution.
The presence in person or by proxy of the holders of a majority of the shares of
Genetic MicroSystems stock entitled to vote is necessary to constitute a quorum
for the transaction of business at the special meeting.



     Genetic MicroSystems will count shares of its capital stock represented in
person or by proxy for the purpose of determining whether a quorum is present at
the special meeting. Genetic


                                       27
<PAGE>   35


MicroSystems will also treat shares that abstain from voting as shares that are
present and entitled to vote at the special meeting for purposes of determining
whether a quorum exists. If a stockholder abstains from voting, that abstention
will have the practical effect of voting against the adoption of the merger
agreement.


REQUIRED VOTE

     Approval of the merger agreement under Genetic MicroSystems' restated
articles of organization requires the affirmative vote of the holders of:

     - at least two-thirds of the outstanding shares of common stock;

     - a majority of the outstanding shares of Series A convertible preferred
       stock, voting as a separate class; and

     - at least two-thirds of the outstanding shares of Series A convertible
       preferred stock and Series B convertible preferred stock voting, together
       as a single class.

     A majority of the holders of Series A convertible preferred stock, voting
as a separate class, must elect not to treat the merger as a liquidation,
dissolution, or winding up of Genetic MicroSystems.

     Lastly, a majority of the holders of Genetic MicroSystems common stock and
convertible preferred stock, voting together as a single class, must appoint
Jean Montagu as stockholder representative.

PROXIES


     This document is accompanied by a form of proxy to be used at the special
meeting. All shares of Genetic MicroSystems stock entitled to vote and
represented at the Genetic MicroSystems special meeting by properly executed
proxies received before or at the meeting, and not revoked, will be voted at the
meeting according to the instructions indicated on the proxies. If a proxy is
properly executed but no vote is specified, the proxy will be voted for adoption
of the merger agreement and approval of the merger.


     If any other matters are properly presented for consideration at the
Genetic MicroSystems special meeting, the persons named in the enclosed form of
proxy will have the discretion to vote on those matters using their best
judgment. Additional matters which may come before the meeting include
consideration of a motion to adjourn the meeting to another time and/or place,
which may be necessary for the purpose of soliciting additional proxies from
Genetic MicroSystems stockholders. The proxy holders will not adjourn the
meeting if there are insufficient votes to approve the proposals at the date of
the meeting.

REVOCABILITY OF PROXIES


     Any proxy you give pursuant to this solicitation may be revoked at any time
before it is voted. To revoke a proxy, you must:


     - submit a later dated proxy with respect to the same shares at any time
       before the vote on the adoption of the merger agreement,


     - deliver written notice of revocation to the Corporate Clerk of Genetic
       MicroSystems at any time before the vote, or


     - attend the special meeting and vote in person.

                                       28
<PAGE>   36

     Your attendance at the special meeting alone is not sufficient to revoke a
proxy.

     Any written notice of revocation or subsequent proxy must be delivered at
or before the taking of the vote at the special meeting to Genetic MicroSystems,
Inc., 34 Commerce Way, Woburn, Massachusetts 01801, Attention: Peter Lewis,
Corporate Clerk.

SOLICITATION OF PROXIES


     Affymetrix will pay the expenses of the solicitation of proxies for the
special meeting including the cost of printing and mailing this document. In
addition to solicitation by mail, directors, officers and employees of Genetic
MicroSystems may solicit proxies in person or by telephone, fax or other means
of communication. These directors, officers and employees will not receive
additional compensation.



GENETIC MICROSYSTEMS STOCKHOLDERS SHOULD NOT SEND ANY STOCK CERTIFICATES WITH
THEIR PROXY CARDS.


                                APPRAISAL RIGHTS


     If the merger is completed, holders of Genetic MicroSystems capital stock
who object to the merger are entitled to appraisal rights under Massachusetts
law. In order to exercise appraisal rights, Genetic MicroSystems stockholders
must strictly adhere to the provisions of Massachusetts law governing appraisal
rights. The following is a summary of the relevant provisions of Massachusetts
law. The description below is only a summary and you should refer to the
relevant provisions of Massachusetts law, a copy of which is attached to this
document as Appendix E.


     In order to exercise your appraisal rights, you must take the following
steps:

     - send a written objection to the merger to Genetic MicroSystems before the
       special meeting stating your intention to demand payment for your shares
       of Genetic MicroSystems capital stock if the merger is approved and the
       merger occurs;

     - DO NOT vote in favor of the merger; and


     - send a written demand to Genetic MicroSystems for payment for your
       Genetic MicroSystems shares within twenty days after you receive notice
       from Genetic MicroSystems that the merger has occurred. Genetic
       MicroSystems will send the notice within 10 days after the merger is
       completed.


     The written objection and written demand should be delivered to Genetic
MicroSystems, Inc., 34 Commerce Way, Woburn, Massachusetts 01801, Attention:
Peter Lewis, Corporate Clerk. We recommend that you send the objection and
demand by registered or certified mail, return receipt requested.


     Please note that, if you file a written objection with Genetic MicroSystems
before the special meeting, you do not need to vote against the merger. However,
if you file a written objection with Genetic MicroSystems before the special
meeting and vote in favor of the merger, you will waive your right to exercise
appraisal rights.


     If you have followed the procedures set forth above and the merger is
completed, Genetic MicroSystems will contact you within 10 days after the
effective time of the merger in order to determine the fair value of your
Genetic MicroSystems capital stock. The "fair value" of your Genetic
MicroSystems capital stock will be determined as of the day before approval of
the merger by the Genetic MicroSystems stockholders and will exclude any value
arising from the expectation of

                                       29
<PAGE>   37

the merger. If Genetic MicroSystems and you have not agreed as to the fair value
of your stock within 30 days after you receive notice from Genetic MicroSystems
that the merger has occurred, both you and Genetic MicroSystems will have the
right to have the court determine the fair value by filing a bill in equity in
the Superior Court Department of Middlesex County, Massachusetts no later than
four months after the expiration of the negotiation period.

     After filing the bill in equity, the court or a special master will hold a
hearing and enter a decree determining the fair value of your Genetic
MicroSystems capital stock and ordering Genetic MicroSystems to make payment to
you of such value. You will also be paid interest from the date of the special
meeting to the time that you surrender your certificates representing your
shares of Genetic MicroSystems capital stock to the exchange agent. The
determination of fair value made by the court or special master will be binding
on and enforceable by you and the other Genetic MicroSystems stockholders who
have properly executed their appraisal rights.

     The fair value of the Genetic MicroSystems capital stock could be worth
more than, the same as or less than the value of the Affymetrix common stock you
would otherwise have received by exchanging your shares of Genetic MicroSystems
capital stock for shares of Affymetrix common stock.

     Your appraisal rights are your only remedy if you object to the merger,
unless the merger is determined to have been illegal, fraudulent or in breach of
the fiduciary duties of the Genetic MicroSystems board of directors.

     If you exercise your appraisal rights, after the merger is completed you
will not have any rights as a Genetic MicroSystems or Affymetrix stockholder,
including the right to receive notices of meetings, vote at meetings or receive
dividends, if any.

                                       30
<PAGE>   38

                                   THE MERGER


GENERAL



     If the holders of two-thirds of the outstanding shares of Genetic
MicroSystems common stock and convertible preferred stock entitled to vote at
the special meeting adopt the merger agreement and the other conditions to
closing are satisfied or waived, Genetic MicroSystems will merge into GMS
Acquisition, a wholly owned subsidiary of Affymetrix. As a result of the merger,
Genetic MicroSystems will become a wholly owned subsidiary of Affymetrix. In the
merger each holder of Genetic MicroSystems stock will be entitled to receive
from Affymetrix, in exchange for each share of Genetic MicroSystems stock, an
amount of Affymetrix common stock equal to an exchange ratio calculated as
described below.


MERGER CONSIDERATION


     Affymetrix will exchange an aggregate of up to 1,070,000 shares of
Affymetrix common stock for all the Genetic MicroSystems common and convertible
preferred shares:



     - outstanding immediately before the effective time of the merger; and


     - subject to options or warrants immediately prior to the effective time of
       the merger, whether vested or unvested or currently exercisable or
       unexercisable.


     The number of Affymetrix shares each Genetic MicroSystems stockholder is
entitled to receive will be calculated immediately before the effective time of
the merger by dividing 1,070,000 by the aggregate number of Genetic MicroSystems
shares outstanding and Genetic MicroSystems shares subject to Genetic
MicroSystems options or warrants. Based on the number of shares, options and
warrants outstanding as of November 12, 1999, stockholders of Genetic
MicroSystems will receive approximately 0.2832 of a share of Affymetrix common
stock for each share of Genetic MicroSystems common stock or convertible
preferred stock. This exchange ratio, however, is subject to reduction if
Genetic MicroSystems issues or grants additional shares, options or warrants in
the ordinary course of business before the effective time of the merger. In
addition, 10% of the aggregate number of shares of Affymetrix common stock to be
delivered by Affymetrix at the closing of the merger will be placed in an escrow
fund to satisfy indemnification obligations of Genetic MicroSystems. See
"Indemnification and Liability Obligations" on page 49 and "Escrow Agreement" on
page 54.


     Each outstanding option or warrant to purchase Genetic MicroSystems common
stock or convertible preferred stock, will be converted into an option or
warrant to acquire the number of shares of Affymetrix common stock that the
holder would have received in the merger if the holder had exercised the option
or warrant immediately prior to the closing of the merger and the exercise price
will be adjusted appropriately.

     Genetic MicroSystems stockholders will not receive fractional shares of
Affymetrix common stock. Instead, a stockholder will receive the cash value,
without interest, of any fractional share of Affymetrix common stock that a
stockholder might otherwise have been entitled to receive, which payment
represents the stockholder's proportionate interest in the net proceeds from the
sale by the exchange agent of the aggregate fractional shares of Affymetrix
common stock.

                                       31
<PAGE>   39

SCHEDULE OF IMPORTANT DAYS

     The following schedule shows important dates and events in connection with
the special meeting and the merger:


<TABLE>
<CAPTION>
DATES                                                    EVENTS
- -----                                                    ------
<S>                                      <C>
- --.....................................  Record date for the Genetic
                                         MicroSystems special meeting
- --.....................................  Genetic MicroSystems special meeting
                                         and target date for completion of the
                                         merger
</TABLE>


BACKGROUND OF THE MERGER


     In September 1998, representatives of Genetic MicroSystems and Affymetrix
met informally at an industry conference in Miami, Florida. At this meeting, the
parties discussed the possibility of a license to Genetic MicroSystems of
Affymetrix intellectual property.


     By spring of 1999, the parties had entered into a confidentiality agreement
and discussions moved to a possible collaborative relationship between the
companies, ranging from collaboration on instrument development to the
possibility of Affymetrix' acquiring Genetic MicroSystems.

     At various times between June and July of 1999, Affymetrix made proposals
to Genetic MicroSystems for a stock-for-stock merger. Genetic MicroSystems
rejected these proposals and made counteroffers, concluding that in each case
the Affymetrix proposal was inadequate in light of the circumstances existing at
the time the proposal was made.

     On July 6, 1999, Affymetrix and Genetic MicroSystems discussed an
acquisition price valued at $85 million in Affymetrix common stock, pending
additional financial and legal due diligence. On July 8, 1999, at a telephonic
meeting of Affymetrix' board, Stephen Fodor, the Chief Executive Officer of
Affymetrix, updated Affymetrix' directors on the state of negotiations with
Genetic MicroSystems.


     During the months of July and August, both Affymetrix and Genetic
MicroSystems engaged in financial and legal due diligence. During this time,
Genetic MicroSystems engaged Palmer & Dodge LLP as its legal advisor and
Affymetrix engaged Sullivan & Cromwell as its legal advisor. Neither Genetic
MicroSystems nor Affymetrix engaged any investment bankers or financial advisors
in connection with the Merger.


     On August 18, 1999, Affymetrix management provided a summary document of
the acquisition proposals, due diligence progress and outstanding negotiation
points to Affymetrix' board of directors.

     On August 19, 1999, Sue Siegel, the then Senior Vice President of Marketing
and Sales and currently the President of Affymetrix, provided a revised proposal
for a stock-for-stock merger to Jean Montagu, President and Chief Executive
Officer of Genetic MicroSystems. Based on the average closing price of
Affymetrix common stock for the 40 consecutive trading days prior to the date of
the proposal, the proposal had a value of $70 million in Affymetrix common
stock. Mr. Montagu agreed to consider the new proposal and to discuss it with
Genetic MicroSystems' senior management and board.

     Mr. Montagu met with Genetic MicroSystems' senior managers, as well as its
legal advisor. After extensive discussions regarding the strategic benefits of
the merger, technology leveraging, synergies and other financial and operating
benefits that could be obtained through a merger between

                                       32
<PAGE>   40

the two companies, Genetic MicroSystems decided to meet again with Affymetrix to
discuss its proposal.


     On August 24, 1999, in a conference call between the senior managers and
legal advisors of each of Affymetrix and Genetic MicroSystems, the parties
agreed to proceed based upon an acquisition price of up to 1,070,000 shares of
Affymetrix common stock for all the outstanding Genetic MicroSystems stock and
all of the shares of Genetic Microsystems stock subject to stock options and
warrants. Shortly thereafter, the parties executed an exclusivity agreement and
began negotiating the terms of the proposed merger.



     On August 25, 1999, at an Affymetrix telephonic board meeting, various
members of Affymetrix' management team provided information to the board of
directors of Affymetrix regarding results of the due diligence review, technical
parameters of Genetic MicroSystems' product line and its performance, the
potential structure of an acquisition, the business risks involved with an
acquisition of Genetic MicroSystems and other issues relating to the merger.


     On September 8, 1999 and September 9, 1999, the senior managers and legal
advisors of both Affymetrix and Genetic MicroSystems met at the offices of
Sullivan & Cromwell in New York City to discuss and negotiate the terms of the
proposed merger.


     On September 9, 1999, Affymetrix' board held a telephonic board meeting to
consider approval of the merger agreement, the stock option agreement and
stockholder voting agreements and the transactions contemplated by those
agreements. After questions by and discussion among Affymetrix' board, the
Affymetrix board, by a unanimous vote of directors present and voting, adopted
the merger agreement and approved entering into the merger agreement, stock
option agreement, stockholder voting agreements and the transactions
contemplated by those agreements.


     Also on September 9, 1999, the board of Genetic MicroSystems held a
telephonic board meeting to consider the merger agreement and the stock option
agreement and the transactions contemplated by those agreements. After hearing
presentations from its legal advisors and discussing the matter, Genetic
MicroSystems' board unanimously approved entering into the merger agreement and
the stock option agreement and the transactions contemplated by those
agreements.


     On September 10, 1999, Affymetrix and Genetic MicroSystems entered into the
merger agreement, the stock option agreement and a letter of intent to negotiate
the terms of an escrow agreement. Also on that date, six stockholders of Genetic
MicroSystems executed voting agreements granting Affymetrix sufficient voting
power to effect the merger. The transaction was publicly announced on September
13, 1999.


     Shortly after the execution of the merger agreement and the stock option
agreement and as contemplated by the merger agreement, Genetic MicroSystems,
Affymetrix, Mr. Montagu and Bank One, as escrow agent, entered into an escrow
agreement dated as of September 10, 1999.

GENETIC MICROSYSTEMS' REASONS FOR THE MERGER; RECOMMENDATION OF THE GENETIC
MICROSYSTEMS BOARD

     In reaching its decision to approve the merger agreement and to recommend
approval of the merger agreement by the Genetic MicroSystems stockholders, the
Genetic MicroSystems board of directors consulted with its management team and
legal advisors. Genetic MicroSystems did not employ the services of any
investment bankers or financial advisors in connection with the merger. Genetic
MicroSystems' board of directors also independently considered the proposed
merger agreement and the transactions contemplated by the merger agreement. The
following factors

                                       33
<PAGE>   41

considered by the Genetic MicroSystems board of directors in making its decision
is not intended to be exhaustive but includes all material factors considered.


     Genetic MicroSystems' board believes the following are reasons that the
merger will be beneficial to Genetic MicroSystems and its stockholders:



     - the markets that Genetic MicroSystems and Affymetrix serve are
       complementary and the merger will have beneficial effects for customers;


     - synergies exist between Genetic MicroSystems and Affymetrix with regard
       to instrumentation development as well as expansion of the sales, service
       and customer support network;

     - Affymetrix owns and has rights to considerable intellectual property that
       Genetic MicroSystems could obtain rights to, thus enabling a greater
       freedom to serve its customers efficiently;

     - the merger would provide access to capital resources needed to compete in
       this rapidly expanding marketplace; and


     - the opportunity to own stock of the combined entity would provide
       stockholders with greater liquidity and a possibility of a better return
       on stockholder investment.


     In the course of its deliberations, the Genetic MicroSystems board of
directors and senior managers reviewed a number of other factors relevant to the
merger. In particular, the Genetic MicroSystems board of directors considered,
among other things:

     - information relating to the business, assets, management, competitive
       position, operating performance, trading performance and prospects of
       each of Genetic MicroSystems and Affymetrix, including the prospects of
       Genetic MicroSystems if it were to continue as an independent company;

     - the current and historical market prices of the Affymetrix common stock
       and the risks associated with ownership of Affrymetrix common stock;


     - the possibility of other alternatives to the merger to increase
       stockholder value;


     - the impact of the merger on Genetic MicroSystems' and Affymetrix'
       customers, suppliers and employees;

     - the likelihood that the merger would be completed;


     - the terms of the merger agreement, including representations and
       warranties, conditions to closing and rights of termination, and
       provisions permitting the Genetic MicroSystems board of directors to
       terminate the merger agreement in response to a third party proposal
       which the Genetic MicroSystems board of directors determines in its good
       faith judgment to be more favorable to Genetic MicroSystems stockholders
       than the merger; and


     - the expected qualification of the merger as a reorganization under
       Section 368(a) of the Internal Revenue Code.

     The Genetic MicroSystems board of directors also identified and considered
a number of potentially negative factors in its deliberations concerning the
merger, including:

     - the risk that the operations of Affymetrix and Genetic MicroSystems might
       not be successfully integrated;

                                       34
<PAGE>   42

     - the risk that, despite the efforts of Affymetrix and Genetic MicroSystems
       after the merger, key personnel might leave the combined company;

     - the difficulty of managing operations in the different geographic
       locations in which Genetic MicroSystems and Affymetrix operate and will
       continue to operate; and

     - the risk that the potential benefits of the merger might not be fully
       realized.

     The Genetic MicroSystems board of directors believes that certain of these
risks are unlikely to occur, that Genetic MicroSystems can avoid or mitigate
others, and that, overall, these risks are outweighed by the potential benefits
of the merger.

     In view of the variety of factors considered in connection with its
evaluation of the merger agreement and the merger, Genetic MicroSystems' board
of directors did not find it practicable to and did not quantify or otherwise
assign relative weight to the specific factors considered in making its
determination. In addition, individual members of Genetic MicroSystems' board of
directors may have given different weight to different factors.

MATERIAL FEDERAL INCOME TAX CONSEQUENCES


     The following is a summary of the material anticipated U.S. federal income
tax consequences of the merger. This summary is:



     - limited to U.S. holders, who are United States persons who hold their
       Genetic MicroSystems stock as a "capital asset" and whose "functional
       currency" is the U.S. dollar;



     - based on the Internal Revenue Code of 1986, Treasury regulations,
       administrative rulings and court decisions, all as in effect as of the
       date of this document and all of which are subject to change at any time,
       possibly with retroactive effect, or different interpretation;



     - not a complete description of all of the considerations that may be
       relevant to a decision whether to approve the merger and, in particular,
       may not address U.S. federal income tax considerations applicable to
       stockholders subject to special treatment under U.S. federal income tax
       law, which would include, for example:



        - non-U.S. persons;



        - financial institutions;



        - regulated investment companies;



        - real estate investment trusts;



        - real estate mortgage investment conduits;



        - financial asset securitization investment trusts;



        - dealers in securities or currencies;



        - traders in securities that elect to mark to market;



        - insurance companies, tax-exempt entities;



        - holders owning Genetic MicroSystems stock as part of a hedge,
          straddle, short sale or conversion transaction; and


                                       35
<PAGE>   43


        - holders who acquired their Genetic MicroSystems stock as a result of
          the exercise of an employee option or otherwise as compensation.



     In addition, no information is provided in this document with respect to
the tax consequences of the merger under applicable foreign, state or local
laws. HOLDERS OF GENETIC MICROSYSTEMS STOCK ARE URGED TO CONSULT WITH THEIR OWN
TAX ADVISORS REGARDING THE FEDERAL INCOME AND OTHER TAX CONSEQUENCES OF THE
MERGER TO THEM, INCLUDING THE EFFECTS OF STATE, LOCAL AND FOREIGN TAX LAWS.



     United States person means:


     - a citizen or resident of the United States;


     - a corporation created or organized in or under the laws of the United
       States or any state within the U.S.;


     - an estate whose income is subject to United States federal income tax
       regardless of its source; or

     - a trust if a United States court can exercise primary supervision over
       the trust's administration and one or more United States persons are
       authorized to control all substantial decisions of the trust or a trust
       that has made a valid election to be taxed as a domestic trust for United
       States federal income tax purposes.

     Affymetrix and Genetic MicroSystems have not requested and do not plan to
request any rulings from the IRS concerning the tax treatment of the merger. The
statements in this document and the opinions of counsel referred to herein are
not binding on the IRS or a court. As a result, neither Affymetrix nor Genetic
MicroSystems can assure you that the tax considerations or opinions contained in
this summary will not be challenged by the IRS or sustained by a court if
challenged by the IRS.


     This summary is based upon the opinion of Sullivan & Cromwell, counsel to
Affymetrix, and Palmer & Dodge LLP, counsel to Genetic MicroSystems. These
opinions, which are attached as Exhibits 8.1 and 8.2 to this document, are based
upon certain facts, assumptions and representations, including the assumption
that the merger will be consummated as described in this document and that the
representations contained in certificates of officers of Affymetrix, GMS
Acquisition and Genetic MicroSystems delivered in connection with the tax
opinions will be accurate through the closing of the merger. Based on the
foregoing, the merger will constitute a "reorganization" within the meaning of
Section 368(a) of the Internal Revenue Code. As a "reorganization," the merger
will have the following principal U.S. federal income tax consequences:



     - no gain or loss will be recognized by Affymetrix, GMS Acquisition, or
       Genetic MicroSystems by reason of the merger;



     - no gain or loss will be recognized by U.S. holders of Genetic
       MicroSystems stock who exchange their Genetic MicroSystems stock for
       Affymetrix common stock pursuant to the merger, except with respect to
       any cash received in lieu of a fractional share of Affymetrix common
       stock (as discussed below);



     - the aggregate tax basis of the Affymetrix common stock received in the
       merger by each U.S. holder of Genetic MicroSystems stock will be the same
       as the aggregate tax basis of the Genetic MicroSystems stock surrendered
       in exchange therefor, reduced by any amount of tax basis allocable to a
       fractional share interest in Affymetrix common stock for which cash is
       received; and


     - the holding period of Affymetrix common stock received in the merger will
       include the holding period for the Genetic MicroSystems stock surrendered
       in exchange therefor.

                                       36
<PAGE>   44


     Cash received by a U.S. holder of Genetic MicroSystems stock in lieu of a
fractional share of Affymetrix common stock will be treated as received in
disposition of such fractional share. These types of holders will generally
recognize capital gain or loss measured by the difference between the amount of
cash received and the portion of the tax basis of the holder's Genetic
MicroSystems stock allocable to the fractional share interest. In addition, a
U.S. holder of Genetic MicroSystems stock who exercises appraisal rights and
receives solely cash in exchange for that holder's Genetic MicroSystems stock
will generally recognize capital gain or loss measured by the difference between
the amount of cash received therefor and the tax basis of that holder's Genetic
MicroSystems stock surrendered. However, dissenters that also own Affymetrix
stock, directly or constructively, could possibly be subject to dividend
treatment on this cash payment. Such capital gain or loss, in either case, will
be long-term capital gain or loss if that holder has held its Genetic
MicroSystems stock for more than one year. In the case of individuals, the
maximum federal income tax rate applicable to long-term capital gains is
generally 20%.



     In addition, the obligations of the parties to consummate the merger are
conditioned upon the receipt by Affymetrix of an opinion from Sullivan &
Cromwell, and the receipt by Genetic MicroSystems of an opinion from Palmer &
Dodge LLP, in each case based upon a number of facts, assumptions and
representations, that the merger will constitute a "reorganization" within the
meaning of Section 368(a) of the Internal Revenue Code and that Affymetrix,
Genetic MicroSystems and GMS Acquisition will be "parties to the reorganization"
within the meaning of Section 368(b) of the Internal Revenue Code.



     BACKUP WITHHOLDING.  Unless a holder of Genetic MicroSystems stock complies
with reporting and/or certification procedures or establishes that it is an
exempt recipient, cash payments in exchange for such holder's Genetic
MicroSystems stock in the merger may be subject to "backup withholding" at a
rate of 31% for federal income tax purposes. Any amounts withheld under the
backup withholding rules may be allowed as a refund or a credit against the
holder's federal income tax liability, provided the required information is
furnished to the IRS.



THE ABOVE SUMMARY IS NOT INTENDED TO CONSTITUTE A COMPLETE ANALYSIS OF ALL OF
THE U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE MERGER. THIS DISCUSSION IS
INCLUDED FOR GENERAL INFORMATION PURPOSES ONLY AND SHOULD NOT BE CONSIDERED AS
LEGAL OR TAX ADVICE. THIS SUMMARY MAY NOT APPLY TO A PARTICULAR STOCKHOLDER IN
LIGHT OF THE STOCKHOLDER'S PARTICULAR CIRCUMSTANCES.


ACCOUNTING TREATMENT


     Completion of the merger is conditioned on receipt by Affymetrix and
Genetic MicroSystems of a letter from Ernst & Young LLP, their respective
independent auditors, regarding the appropriateness of "pooling-of-interests"
accounting for the merger if closed and consummated in accordance with the
merger agreement. Under this method of accounting, Affymetrix will retroactively
restate its consolidated financial statements at the effective time of the
merger to include the assets, liabilities, stockholders' equity and results of
operations of Genetic MicroSystems as if the companies had always been combined.
See "The Merger Agreement -- Conditions to the Merger" on page 41 and "The
Merger Agreement -- Additional Covenants -- Pooling-of-Interests" on page 46.
The unaudited pro forma financial information contained in this document has
been prepared using the "pooling-of-interests" method of accounting.


REGULATORY APPROVALS

HART-SCOTT-RODINO


     The Federal Trade Commission and the Antitrust Division of the Department
of Justice frequently scrutinize the legality under the antitrust laws of
transactions such as the merger. At any time before or after the merger, the DOJ
or the FTC could take action under the antitrust laws as it

                                       37
<PAGE>   45


deems necessary or desirable in the public interest, including seeking to enjoin
the merger or seeking divestiture of substantial assets of Affymetrix or Genetic
MicroSystems or their subsidiaries. Private parties and state attorneys general
may also bring an action under the antitrust laws. There can be no assurance
that a challenge to the merger on antitrust grounds will not be made or, if such
a challenge is made, of the result.



     On October 6, 1999, Affymetrix and Genetic MicroSystems filed their
respective Pre-Merger Notification and Report Forms with the FTC and the DOJ
under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. The HSR Act, and
the rules and regulations thereunder, provide that certain merger transactions,
including the merger, may not be consummated until required information and
materials have been furnished to the DOJ and the FTC and certain waiting periods
have expired or been terminated. On November 5, 1999 the 30-day HSR waiting
period expired.


OTHER REGULATORY APPROVALS


     The merger is conditioned on Affymetrix and Genetic MicroSystems making or
obtaining all required filings and all required consents, approvals and
authorizations before the closing of the merger from any governmental entity.


FEDERAL SECURITIES LAWS CONSEQUENCES


     All shares of Affymetrix common stock received by Genetic MicroSystems
stockholders in the merger who are not affiliates of Genetic MicroSystems before
the merger will be freely transferable. However, shares of Affymetrix common
stock received by persons who are affiliates of Genetic MicroSystems before the
merger may be resold by them only in transactions permitted by the resale
provisions of Rule 145 under the Securities Act of 1933, or Rule 144 promulgated
under the Securities Act in the case of those persons who become affiliates of
Affymetrix, or as otherwise permitted under the Securities Act. Affiliates of
Genetic MicroSystems are those individuals or entities that control, are
controlled by, or are under common control with, Genetic MicroSystems.
Affiliates generally include executive officers and directors of Genetic
MicroSystems as well as principal stockholders of Genetic MicroSystems. This
document does not cover any resales of Affymetrix common stock received by
affiliates of Genetic MicroSystems in the merger.


NASDAQ NATIONAL MARKET TRADING


     It is a condition to the merger that Affymetrix file the appropriate
notification form for quotation of Affymetrix common stock to be issued in the
merger with the NASDAQ and pay the applicable fee. Therefore, the shares of
Affymetrix common stock to be issued in connection with the merger will be
approved for quotation on the NASDAQ National Market. If we complete the merger,
stockholders will be able to trade the shares of Affymetrix common stock they
receive in the merger on the NASDAQ National Market. Genetic MicroSystems is a
privately held company with fewer than ninety stockholders and is not listed on
any exchange, quoted on any trading market or subject to reporting requirements
under the Securities Exchange Act. Consequently, Genetic MicroSystems does not
need to make any filings under the Securities Exchange Act or any stock exchange
with respect to the merger.


                                       38
<PAGE>   46

                              THE MERGER AGREEMENT


     This section of this document describes the material terms of the merger
agreement. The merger agreement is incorporated in this document by reference.
The following description of the merger agreement is not complete and you should
read the merger agreement, and the other information that is incorporated by
reference in this document, carefully and in its entirety for a more complete
understanding of the merger.


INTRODUCTION


     The merger agreement provides for a merger of Genetic MicroSystems into GMS
Acquisition, a wholly owned subsidiary of Affymetrix. We intend for the
transaction to qualify as a "pooling-of-interests" for accounting and financial
reporting purposes and to qualify as a tax-free "reorganization" within the
meaning of Section 368(a) of the Internal Revenue Code for federal income tax
purposes.


CLOSING AND EFFECTIVE TIME OF THE MERGER

CLOSING

     The closing of the merger will take place on the later of:


     - January 14, 2000 or an earlier date which Affymetrix may select; or



     - the first business day on which all closing conditions have been
       satisfied or waived.



Alternatively, the merger may take place at any other time as Affymetrix and
Genetic MicroSystems agree in writing. The closing is expected to take place
shortly after the approval of the merger by the Genetic MicroSystems
stockholders.


EFFECTIVE TIME


     The merger will be effective upon the filing articles of merger with the
Secretary of State of the Commonwealth of Massachusetts, unless the articles of
merger specify a later effective date, in which case the merger will be
effective on the later date. We anticipate that the filing of articles of merger
will be made simultaneously with, or as soon as practicable after, the closing
of the merger. See "The Merger Agreement -- Conditions to the Merger" on page
41.


EXCHANGE OF STOCK CERTIFICATES


     GENETIC MICROSYSTEMS STOCKHOLDERS SHOULD NOT SEND STOCK CERTIFICATES WITH
THEIR PROXY CARD AND SHOULD NOT SURRENDER STOCK CERTIFICATES PRIOR TO THE
ADOPTION OF THE MERGER AGREEMENT AND THE RECEIPT OF A TRANSMITTAL FORM.


FRACTIONAL SHARES


     Affymetrix will not issue any fractional shares of its common stock to any
Genetic MicroSystems stockholder in connection with the merger. Each Genetic
MicroSystems stockholder who is entitled to receive a fraction of a share of
Affymetrix common stock will receive cash, without interest, in an amount equal
to the stockholder's proportionate interest in the net proceeds from the sale of
all of the aggregate fractional shares of Affymetrix common stock.


                                       39
<PAGE>   47

EXCHANGE PROCEDURES


     Promptly after the effective time, Affymetrix' exchange agent will mail
transmittal forms and exchange instructions to each holder of record of Genetic
MicroSystems common or convertible preferred stock. Each holder of Genetic
MicroSystems common or convertible preferred stock certificates will be able to
surrender stock certificates to the exchange agent. Each certificate surrendered
shall be canceled, and each holder will receive in exchange certificates
evidencing the number of whole shares of Affymetrix common stock to which the
holder is entitled, any cash which may be payable instead of a fractional share
of Affymetrix common stock and any dividends or other distributions on
Affymetrix common stock with a record date at or after the effective time of the
merger.


DIVIDENDS AND DISTRIBUTIONS


     All shares of Affymetrix common stock that Affymetrix issues in the merger
will be treated as outstanding as of the effective time of the merger. Whenever
a dividend or other distribution is declared on Affymetrix common stock, and the
record date for the dividend or distribution is at or after the effective time
of the merger, that declaration will include dividends or other distributions on
all shares of Affymetrix common stock which may be issued under the merger
agreement. No dividends or other distributions on the Affymetrix common stock
will be paid to any holder of Genetic MicroSystems common or convertible
preferred stock until the stockholder surrenders the certificate for exchange.


EXCHANGE AND CANCELLATION OF GENETIC MICROSYSTEMS STOCK OPTIONS


     At the effective time, each outstanding Genetic MicroSystems stock option,
whether vested or unvested, will become an option to acquire, on substantially
the same terms and conditions as were applicable under the Genetic MicroSystems
stock option, the same number of shares of Affymetrix common stock as the holder
of the Genetic MicroSystems stock option would have received in connection with
the merger had the holder exercised the option in full immediately before the
effective time of the merger. The new option will have an exercise price per
share equal to the aggregate exercise price for the common stock otherwise
purchasable under the Genetic MicroSystems stock option divided by the number of
full shares of Affymetrix common stock purchasable under the Genetic
MicroSystems stock option.


EXCHANGE OF GENETIC MICROSYSTEMS WARRANTS


     At the effective time, outstanding warrants to purchase Genetic
MicroSystems convertible preferred stock will become warrants to acquire, on
substantially the same terms and conditions as were applicable under the Genetic
MicroSystems warrants, the same number of shares of Affymetrix common stock the
holder of that Genetic MicroSystems warrant would have been entitled to receive
pursuant to the merger agreement had that holder exercised such Genetic
MicroSystems warrant in full immediately before the effective time of the
merger.


                                       40
<PAGE>   48

CONDITIONS TO THE MERGER

CONDITIONS TO EACH PARTY'S OBLIGATIONS


     The obligations of Genetic MicroSystems, Affymetrix and GMS Acquisition to
effect the merger are subject to the satisfaction or waiver, at or before the
effective time of the merger, of each of the following conditions:



     - STOCKHOLDER APPROVAL.  The merger agreement shall have been approved by
       vote:



        - of the holders of two-thirds of the shares of Genetic MicroSystems
          common stock outstanding and entitled to vote as of the record date
          for the special meeting;



        - of the holders of two-thirds of the shares of Genetic MicroSystems
          convertible preferred stock outstanding and entitled to vote as of the
          record date for the special meeting;



        - of the holders of a majority of the shares of Genetic MicroSystems
          Series A convertible preferred stock outstanding and entitled to vote
          as of the record date for the special meeting; and



        - of Affymetrix as sole stockholder of GMS Acquisition;



    A majority of the shares of Genetic MicroSystems Series A convertible
    preferred stock outstanding and entitled to vote as of the record date for
    the special meeting must also affirmatively vote that the merger does not
    constitute a liquidation, dissolution or winding up of Genetic MicroSystems;



     - NASDAQ QUOTATION.  Affymetrix must file with the NASDAQ National Market
       the appropriate notification form for quotation of Affymetrix common
       stock to be issued in the merger and Affymetrix must pay the applicable
       fee;



     - HART-SCOTT-RODINO ACT.  The waiting period applicable to the consummation
       of the merger under the Hart-Scott-Rodino Antitrust Improvements Act must
       expire or be terminated. Other than the filing of the articles of merger,
       each party must make or obtain all notices, other filings, consents,
       permits and authorizations required to be made or obtained prior to the
       effective time from any governmental entity in connection with the
       execution and delivery of the merger agreement and the consummation of
       the merger;



     - LITIGATION.  No court or governmental entity of competent jurisdiction
       shall have enacted, issued, promulgated, enforced or entered any statute,
       law, ordinance, rule, regulation, judgment, decree, injunction or other
       order that is in effect and restrains, enjoins or otherwise prohibits
       consummation of the merger or the other transactions contemplated by the
       merger agreement, and no governmental entity or any other person shall
       have instituted any proceeding or threatened to institute any proceeding
       seeking an order;



     - ACCOUNTANT LETTER.  Affymetrix and Genetic MicroSystems must receive a
       letter, dated as of the closing date, from Ernst & Young LLP regarding
       the appropriateness of pooling-of-interests accounting for the merger
       under Accounting Principles Board Opinion No. 16 if the merger is closed
       and consummated under the merger agreement;



     - S-4 REGISTRATION STATEMENT.  The registration statement of which this
       document is a part must become effective under the Securities Act. No
       stop order suspending the effectiveness of the registration statement
       shall have been issued, and no proceedings for that purpose shall have
       been initiated or threatened, by the Securities and Exchange Commission;
       and


                                       41
<PAGE>   49


     - TAX OPINIONS.  Affymetrix and Genetic MicroSystems must receive
       substantially identical written opinions from their counsel, Sullivan &
       Cromwell and Palmer & Dodge LLP, respectively, dated the closing date,
       stating that the merger will be treated for federal income tax purposes
       as a reorganization within the meaning of Section 368(a) of the Internal
       Revenue Code, and that each of Affymetrix, GMS Acquisition, Inc. and
       Genetic MicroSystems will be a party to that reorganization within the
       meaning of Section 368(b) of the Code.


ADDITIONAL CONDITIONS TO AFFYMETRIX' OBLIGATIONS

     The obligations of Affymetrix and GMS Acquisition, Inc. to effect the
merger are also subject to the satisfaction or waiver by Affymetrix at or prior
to the effective time of the merger of the following additional conditions:


     - REPRESENTATIONS AND WARRANTIES.  The representations and warranties of
       Genetic MicroSystems, the stockholders set forth on the signature pages
       of the merger agreement, and the Stockholder Representative on behalf of
       the stockholders of Genetic MicroSystems must be true and correct in all
       respects as of the date of the merger agreement and as of the closing
       date as though made on and as of the closing date, except to the extent
       any representation or warranty speaks as of an earlier date; unless the
       fact that a representation or warranty is not true and correct, has not
       had or is not reasonably likely to have, a material adverse effect on the
       financial condition, properties, prospects, business or results of
       operations of Genetic MicroSystems, and Affymetrix must receive a
       certificate signed on behalf of Genetic MicroSystems to such effect.



     - PERFORMANCE OF OBLIGATIONS OF GENETIC MICROSYSTEMS.  Genetic MicroSystems
       must perform in all material respects all obligations required to be
       performed by it under the merger agreement at or prior to the closing
       date, and Affymetrix must receive a certificate signed on behalf of
       Genetic MicroSystems to such effect.



     - CONSENTS UNDER AGREEMENTS.  Genetic MicroSystems must obtain the consent
       or approval of each person whose consent or approval is required under
       any material contract to which Genetic MicroSystems is a party.



     - LEGAL OPINION.  Affymetrix must receive an opinion of Palmer & Dodge LLP,
       counsel to Genetic MicroSystems, dated the closing date, addressing
       transaction-related matters.



     - RESIGNATIONS.  Affymetrix must receive the resignations of each director
       of Genetic MicroSystems.



     - NONCOMPETITION AGREEMENTS.  Affymetrix and/or GMS Acquisition, Inc. must
       enter into a noncompetition agreement with specified employees of Genetic
       MicroSystems.



     - AFFILIATES LETTERS.  Affymetrix must receive an affiliates letter from
       each person identified as an affiliate of Genetic MicroSystems.


ADDITIONAL CONDITIONS TO GENETIC MICROSYSTEMS' OBLIGATIONS


     The obligation of Genetic MicroSystems to effect the merger is also subject
to the satisfaction or waiver by Genetic MicroSystems at or before the effective
time of the merger of the following additional conditions:



     - REPRESENTATIONS AND WARRANTIES.  The representations and warranties of
       Affymetrix and GMS Acquisition, Inc. must be true and correct in all
       respects as of the date of the merger


                                       42
<PAGE>   50


       agreement and as of the closing date as though made on and as of the
       closing date, except to the extent any representation or warranty speaks
       as of an earlier date; unless the fact that a representation or warranty
       is not true and correct, has not had or is not reasonable likely to have,
       a material adverse effect on the financial condition, properties,
       prospects, business or results of operations of Affymetrix, and Genetic
       MicroSystems must receive a certificate signed on behalf of Affymetrix to
       such effect.



     - PERFORMANCE OF OBLIGATIONS OF AFFYMETRIX AND GMS ACQUISITION, INC.  Each
       of Affymetrix and GMS Acquisition, Inc. must perform in all material
       respects all obligations required to be performed by it under the merger
       agreement at or prior to the closing date, and Genetic MicroSystems must
       receive a certificate signed on behalf of Affymetrix and GMS Acquisition
       to such effect.



     - CONSENTS UNDER AGREEMENTS.  Affymetrix must obtain the consent or
       approval of each person whose consent or approval is required under any
       material contract to which Affymetrix or any of its subsidiaries is a
       party.



     - LEGAL OPINION.  Genetic MicroSystems must receive an opinion of the
       General Counsel of Affymetrix, dated the closing date, addressing
       transaction-related matters.



REPRESENTATIONS AND WARRANTIES OF AFFYMETRIX, GMS ACQUISITION, GENETIC
MICROSYSTEMS, THE STOCKHOLDER REPRESENTATIVE AND STOCKHOLDERS OF GENETIC
MICROSYSTEMS



     The merger agreement contains various customary representations and
warranties of Affymetrix, GMS Acquisition, Inc., Genetic MicroSystems, the
Stockholder Representative and stockholders of Genetic MicroSystems relating to,
among other things:


     - corporate organization, good standing and qualification;

     - capital structure;

     - corporate power and authority to execute, deliver and perform its
       obligations, and to consummate the merger;

     - governmental consents and regulatory approvals necessary to compete the
       merger;

     - the fact that the transactions contemplated by the merger agreement will
       not violate Affymetrix' or Genetic MicroSystems' organizational
       documents, the contracts to which Affymetrix or Genetic MicroSystems is a
       party or any law, rule or regulation;

     - the absence of certain material adverse changes or events;

     - financial statements;

     - accounting and tax matters, including qualification of the merger as a
       "pooling-of-interests" transaction; and

     - brokers and finders.


     In addition, the merger agreement contains additional representations and
warranties of Genetic MicroSystems, the Stockholder Representative and
stockholders of Genetic MicroSystems relating to, among other things:


     - litigation;

     - employee benefit plans;

                                       43
<PAGE>   51

     - compliance with applicable laws and required licenses and permits;

     - antitakeover statutes;

     - environmental matters;

     - tax matters;

     - labor matters;

     - insurance;

     - intellectual property matters;

     - year 2000 compliance;

     - title to property and leases;

     - contracts;

     - disclosure of material facts; and

     - books and records.

CONDUCT OF THE BUSINESS OF GENETIC MICROSYSTEMS PRIOR TO THE MERGER


     Genetic MicroSystems agreed that, prior to the effective time of the
merger, unless Affymetrix otherwise consents in writing and except as otherwise
expressly contemplated in the merger agreement:


     - it will carry out its business in the ordinary and usual course, and will
       use its commercially reasonable best efforts to preserve its business
       organization substantially intact and maintain its existing relations and
       goodwill with customers, suppliers, distributors, creditors, lessors,
       employees and business associates;

     - it will not amend its organizational documents;

     - it will not split, combine or reclassify its outstanding shares of
       capital stock;

     - it will not declare, set aside or pay any dividend payable in cash, stock
       or other property in respect of any capital stock;

     - it will not repurchase, redeem or otherwise acquire any shares of its
       capital stock or any securities convertible into or exchangeable for any
       shares of its capital stock;


     - it will not issue, sell, pledge, dispose of or encumber any shares of, or
       securities convertible into or exchangeable or exercisable for, or
       options, warrants, calls, commitments or rights of any kind to acquire,
       any shares of its capital stock of any class or any voting debt or any
       other property or assets;



     - it will not, other than in the ordinary and usual course of business,
       transfer, lease, license, guarantee, sell, mortgage, pledge, dispose of
       or encumber any other property or assets or incur or modify any material
       indebtedness or other liability;



     - it will not make or authorize or commit for any capital expenditures or,
       by any means, make any acquisition of, or investment in, assets or stock
       of any other person or entity;


                                       44
<PAGE>   52

     - it will not terminate, establish, adopt, enter into, make any new grants
       or awards under (except pursuant to normal advancement and promotion
       procedure consistent with past practice), amend or otherwise modify, any
       compensation and benefit plans or increase or accelerate the salary,
       wage, bonus or other compensation of any employees;

     - it will not settle or compromise any material claims or litigation or,
       except in the ordinary and usual course of business, modify, amend or
       terminate any of its material contracts or waive, release or assign any
       material rights or claims;

     - it will not make any material tax election or permit any insurance policy
       naming it as a beneficiary or loss-payable payee to be canceled or
       terminated except in the ordinary and usual course of business;

     - it will not, except as may be required as a result of a change in
       generally accepted accounting principles and in accordance with the
       written advice of its accountants, change any of the accounting practices
       or principles used by it;

     - it will not adopt a plan of complete or partial liquidation, dissolution,
       merger, consolidation, restructuring, recapitalization, or other
       reorganization of it;

     - it will not take any action or omit to take any action that would cause
       any of its representations and warranties to become untrue in any
       material respect; and

     - it will not authorize or enter into an agreement to do any of the
       foregoing.

NO SOLICITATION OF ACQUISITION PROPOSALS


     The merger agreement provides that Genetic MicroSystems and its officers
and directors shall not, and that Genetic MicroSystems shall direct and use its
best efforts to cause its employees and representatives and agents of Genetic
MicroSystems, including any investment banker, attorney or accountant retained
by Genetic MicroSystems, not to, directly or indirectly:



     - initiate, solicit, encourage or otherwise facilitate any inquiries or the
       making of any proposal or offer with respect to a merger, reorganization,
       share exchange, consolidation or similar transaction involving Genetic
       MicroSystems, or any purchase of 10% or more of the assets or any equity
       securities of Genetic MicroSystems; any such proposal is referred to in
       this document as an "acquisition proposal"; and


     - engage in any negotiations concerning, or provide any confidential
       information or data to, or have any discussions with, any person relating
       to an acquisition proposal, or otherwise facilitate any effort or attempt
       to make or implement an acquisition proposal.

However, Genetic MicroSystems may:


     - provide information in response to a request by a person who has made an
       unsolicited bona fide written acquisition proposal if Genetic
       MicroSystems receives from the requesting person an executed
       confidentiality agreement, if and only to the extent that, Genetic
       MicroSystems determines in good faith after consultation with outside
       legal counsel that such action is necessary in order for its directors to
       comply with their fiduciary duties under applicable law;



     - engage in any negotiations or discussions with any person who has made an
       unsolicited bona fide written acquisition proposal, if and only to the
       extent that, Genetic MicroSystems determines in good faith after
       consultation with outside legal counsel that such action is necessary in
       order for its directors to comply with their fiduciary duties under
       applicable law


                                       45
<PAGE>   53


and Genetic MicroSystems determines in good faith, after consultation with its
financial advisor, that the acquisition proposal, if accepted, is reasonably
likely to be consummated, taking into account all legal, financial and
      regulatory aspects of the proposal and the person making the proposal and
      would, if consummated, result in a transaction more favorable to Genetic
      MicroSystems' stockholders from a financial point of view than the
      transaction contemplated by the merger agreement; any more favorable
      acquisition proposal is referred to in this document as a "superior
      proposal"; and



     - recommend the acquisition proposal to the stockholders of Genetic
       MicroSystems, if and only to the extent that, Genetic MicroSystems
       determines in good faith after consultation with outside legal counsel
       that such action is necessary in order for its directors to comply with
       their respective fiduciary duties under applicable law and Genetic
       MicroSystems determines in good faith, after consultation with its
       financial advisor, that the acquisition proposal is a superior proposal.


The merger agreement also requires that Genetic MicroSystems:


     - notify Affymetrix immediately if any inquiries, proposals or offers are
       received by, any information is requested from, or any discussions or
       negotiations are sought to be initiated or continued with Genetic
       MicroSystems; and



     - indicate to Affymetrix the identity of the offeror and the terms and
       conditions of any acquisition proposal and thereafter keep Affymetrix
       informed of the status and terms of any proposals and the status of any
       negotiations or discussions.


ADDITIONAL COVENANTS

INFORMATION SUPPLIED


     Affymetrix and Genetic MicroSystems agreed that none of the information
they supply for inclusion in the registration statement on Form S-4 filed with
the Securities and Exchange Commission to register the common shares of
Affymetrix to be issued in the merger will contain any untrue statement of a
material fact or omit to state a material fact necessary in order to make those
statements not misleading.


POOLING-OF-INTERESTS


     The merger agreement provides that neither Affymetrix nor Genetic
MicroSystems will take or cause to be taken any action, whether before or after
the effective time of the merger that would disqualify the merger as a
"pooling-of-interests" for accounting purposes. For more detailed information,
see "Accounting Treatment" on page 37.


OTHER AGREEMENTS


     The merger agreement contains additional covenants relating to the conduct
of the parties before the effective time of the merger, including among other
things:



     - in the case of Genetic MicroSystems, to take all action necessary to
       convene a meeting of Genetic MicroSystems stockholders as promptly as
       practicable after the registration statement is declared effective by the
       Securities and Exchange Commission, in order to approve the merger
       agreement;


                                       46
<PAGE>   54

     - to use commercially reasonable best efforts to cause to be delivered to
       the other party "comfort letters" from such party's independent
       accountants;


     - to use commercially reasonable best efforts to take or cause to be taken
       all actions, and do or cause to be done all things necessary to
       consummate and make effective the merger, including promptly making
       filings with applicable governmental entities and obtaining all necessary
       regulatory approvals and consents;


     - not to take or cause to be taken, whether before or after the effective
       time of the merger, any action that would disqualify the merger as a
       "reorganization" within the meaning of Section 368(a) of the Internal
       Revenue Code;

     - in the case of Genetic MicroSystems, to afford Affymetrix reasonable
       access to information pertaining to Genetic MicroSystems and its
       business;


     - to deliver to the other party a list of all individuals that such party
       believes to be "affiliates" of such party and to use commercially
       reasonable best efforts to cause such persons to deliver "affiliates"
       letters' to the other party;



     - in the case of Affymetrix, to file with the NASDAQ National Market the
       appropriate notification form for the quotation of additional shares and
       to pay the applicable fee covering Affymetrix common stock to be issued
       in the merger;


     - in the case of Affymetrix, at the effective time of the merger, assume
       the Genetic MicroSystems stock option plan and reserve a sufficient
       number of shares of Affymetrix common stock for issuance pursuant to such
       options;

     - in the case of Affymetrix, for one year after the effective time of the
       merger, provide continuing Genetic MicroSystems employees benefits under
       employee benefit plans that are no less favorable in the aggregate than
       those currently provided by Genetic MicroSystems to such employees; and

     - in the case of Genetic MicroSystems, at the effective time of the merger,
       assign those noncompetition and nonsolicitation contracts that Genetic
       MicroSystems has entered into with its employees, as Affymetrix may
       request.

TERMINATION, AMENDMENT OR WAIVER

TERMINATION


     The merger agreement may be terminated at any time before the closing date:



     - whether before or after the approval by the stockholders of Genetic
       MicroSystems, by the mutual written consent of Genetic MicroSystems and
       Affymetrix, by action of their boards of directors;


     - by either Affymetrix or Genetic MicroSystems if:


       - the merger is not completed by February 15, 2000, provided that the
         right to terminate after such date will not be available to any party
         that has breached in any material respect its obligations under the
         merger agreement in any manner that shall have contributed to the
         occurrence of the failure of the merger to be consummated;



       - the Genetic MicroSystems stockholders have not approved the merger
         agreement at a meeting duly convened for such purpose; or


                                       47
<PAGE>   55

       - any order permanently restraining, enjoining or otherwise prohibiting
         the merger shall become final and non-appealable.

     - by Genetic MicroSystems under the following circumstances:

       - Genetic MicroSystems is not in breach of any of the terms of the merger
         agreement; and


       - the board of directors of Genetic MicroSystems authorizes, subject to
         the terms of the merger agreement, Genetic MicroSystems to enter into a
         binding written agreement concerning a superior proposal, and Genetic
         MicroSystems notifies Affymetrix in writing that it intends to enter
         into that agreement, attaching the most current version of the
         agreement to such notice; and



       - Affymetrix does not make, within five business days of receipt of
         Genetic MicroSystems' written notification of its intention to enter
         into the agreement, an offer that the Genetic MicroSystems board of
         directors determines is at least as favorable, from a financial point
         of view, to the stockholders of Genetic MicroSystems as the proposal as
         to which Genetic MicroSystems gave notice; and


       - Genetic MicroSystems pays to Affymetrix, prior to such termination, in
         immediately available funds the termination and expense fees that are
         discussed below under the heading "Termination Fee and Expense
         Reimbursement."


     - if there has been a material breach by Affymetrix or GMS Acquisition of
       any representation, warranty, covenant or agreement of Affymetrix or GMS
       Acquisition contained in the merger agreement that is not curable or, if
       curable, is not cured within 30 days after written notice.


- - by Affymetrix if:


     - the Genetic MicroSystems board of directors withdraws or adversely
       modifies its approval or recommendation of the merger agreement or fails
       to reconfirm its recommendation of the merger agreement within five
       business days after a written request by Affymetrix to do so;



     - there has been a material breach by Genetic MicroSystems of any
       representation, warranty, covenant or agreement of Genetic MicroSystems
       contained in the merger agreement that is not curable or, if curable, is
       not cured within 30 days after written notice; or



     - Genetic MicroSystems or any of the other persons described under the
       heading "No Solicitation of Acquisition Proposals" on page 45 takes any
       of the actions that are proscribed by the covenant described under that
       heading.


Neither Affymetrix nor Genetic MicroSystems may terminate the merger agreement
or elect not to complete the merger solely because of changes in the price of
shares of Affymetrix common stock.

                                       48
<PAGE>   56

TERMINATION FEE AND EXPENSE REIMBURSEMENT

     Genetic MicroSystems has agreed to pay to Affymetrix a termination fee
equal to $2,500,000 and to reimburse Affymetrix' expenses up to $1,000,000 if
the merger agreement is terminated under the following circumstances:

     - Genetic MicroSystems terminates the merger agreement because:

       - Genetic MicroSystems is not in breach of any of the terms of the merger
         agreement; and


       - the board of directors of Genetic MicroSystems authorizes, subject to
         the terms of the merger agreement, Genetic MicroSystems to enter into a
         binding written agreement concerning a superior proposal, and Genetic
         MicroSystems notifies Affymetrix in writing that it intends to enter
         into that agreement, attaching the most current version of the
         agreement to such notice; and



       - Affymetrix does not make, within five business days of receipt of
         Genetic MicroSystems' written notification of its intention to enter
         into the agreement, an offer that the Genetic MicroSystems board of
         directors determines is at least as favorable, from a financial point
         of view, to the stockholders of Genetic MicroSystems as the proposal as
         to which Genetic MicroSystems gave notice.


     - Affymetrix terminates the merger agreement because:


       - the Genetic MicroSystems board of directors withdraws or adversely
         modifies its approval or recommendation of the merger agreement or
         fails to reconfirm its recommendation of the merger agreement within
         five business days after a written request by Affymetrix to do so; or



       - Genetic MicroSystems or any of the other persons described under the
         heading "No Solicitation of Acquisition Proposals" on page 45 takes any
         of the actions that are proscribed by the covenant described under that
         heading.


APPOINTMENT OF STOCKHOLDER REPRESENTATIVE


     Under the merger agreement, each holder of shares of Genetic MicroSystems
capital stock who votes in favor of the merger or who receives or accepts shares
of Affymetrix common stock as the merger consideration consents to the
appointment of Jean Montagu as stockholder representative and consents to the
performance by the stockholder representative of all rights and obligations
conferred on the stockholder representative under the merger agreement and the
escrow agreement. The stockholder representative is indemnified by the
stockholders of Genetic MicroSystems for losses and liabilities incurred without
gross negligence or bad faith on the part of the stockholder representive. For
more detailed information on the escrow arrangements, see "Escrow Agreement" on
page 54.


INDEMNIFICATION AND LIABILITY OBLIGATIONS

GENERAL


     Under the merger agreement and the escrow agreement, 10% of the aggregate
number of shares of Affymetrix common stock to be delivered by Affymetrix at the
closing of the merger will be deposited with an escrow agent, based on each
stockholder's ownership percentage in Genetic MicroSystems, for a period not to
exceed one year, for purposes of indemnifying Affymetrix. For more detailed
information on the escrow arrangements, see "Escrow Agreement" on page 54. For a
period of one year after the effective time of the merger, the stockholders of
Genetic MicroSystems


                                       49
<PAGE>   57


will individually or as a group, indemnify and hold harmless Affymetrix and its
affiliates, for, and shall pay to Affymetrix and its affiliates the amount of,
any damages directly or indirectly arising or resulting from or in connection
with:


     - any breach of any representation or warranty made by Genetic
       MicroSystems, the stockholders of Genetic MicroSystems set forth on the
       signature pages of the merger agreement or the stockholder representative
       in the merger agreement or in any certificate delivered by Genetic
       MicroSystems pursuant to the merger agreement;

     - any breach by Genetic MicroSystems of any covenant or obligation of
       Genetic MicroSystems in the merger agreement; or


     - any breach of, or failure to assign to Affymetrix all of the rights under
       and terms of, any contract to which Genetic MicroSystems is a party.


     For a period of one year after the effective time of the merger, Affymetrix
will indemnify and hold harmless the stockholders of Genetic MicroSystems, and
shall pay to such stockholders the amount of any damages arising, directly or
indirectly, from or in connection with:

     - any breach of any representation or warranty made by Affymetrix in the
       merger agreement or in any certificate delivered by Affymetrix pursuant
       to the merger agreement; or

     - any breach by Affymetrix of any covenant or obligation of Affymetrix in
       the merger agreement.

LIMITATIONS ON INDEMNIFICATION

     Genetic MicroSystems stockholders will not have liability for
indemnification as provided by the indemnification procedures in the merger
agreement:


     - unless and until the total amount of all damages, taken together, exceeds
       $500,000, in which case Affymetrix will be entitled to indemnification
       for the entire amount its damages; and



     - for any damages in the aggregate in excess of the 10% escrowed shares of
       Affymetrix common stock, except in connection with a court ruling.



     These limitations will not apply to any breach of Genetic MicroSystems'
representations and warranties of which Genetic MicroSystems had knowledge at
any time prior to the date on which the representation and warranty is made or
any intentional breach by Genetic MicroSystems of any covenant or obligation.


     Affymetrix will not have liability for indemnification or otherwise:


     - unless and until the total amount of all damages, taken together, exceeds
       $500,000, in which case Genetic MicroSystems stockholders will be
       entitled to indemnification for the entire amount of their damages; and



     - for any damages in the aggregate in excess of an amount equal to 535,000
       multiplied by the closing price on the NASDAQ of the shares of Affymetrix
       common stock on the closing date.



     These limitations will not apply to any breach of Affymetrix'
representations and warranties of which Affymetrix had knowledge at any time
prior to the date on which the representation and warranty is made or any
intentional breach by Affymetrix of any covenant or obligation.


                                       50
<PAGE>   58

NON-EXCLUSIVE REMEDY

     The indemnification provisions of the merger agreement are not the
exclusive remedy for Affymetrix. Affymetrix will have the right to recover
damages from the Genetic MicroSystems stockholders pursuant to a judgment from
any court of competent jurisdiction for damages directly or indirectly arising
or resulting from or in connection with:

     - any breach of any representation or warranty made by Genetic
       MicroSystems, the stockholders of Genetic MicroSystems set forth on the
       signature pages of the merger agreement or the stockholder representative
       in the merger agreement or in any certificate delivered by Genetic
       MicroSystems pursuant to the merger agreement;

     - any breach by Genetic MicroSystems of any covenant or obligation of
       Genetic MicroSystems in the merger agreement; or


     - any breach of, or failure to assign to Affymetrix all of the rights under
       and terms of, any contract to which Genetic MicroSystems is a party.


However, Genetic MicroSystems stockholders will not have liability for any
damages in the aggregate in excess of the amount equal to 535,000 multiplied by
the closing price on the NASDAQ of the shares of Affymetrix common stock on the
closing date.

AMENDMENT


     Subject to the provisions of applicable law, at any time prior to the
effective time of the merger, the parties to the merger agreement may modify or
amend the merger agreement, by written agreement executed and delivered by their
duly authorized officers.


WAIVER


     At any time prior to the effective time of the merger, any party to the
merger agreement may extend in writing the time for the performance of any of
the obligations or other acts of any other party to the merger agreement or
waive in writing compliance with any of the agreements of any other party or any
conditions to its own obligations, to the extent such obligations, agreements
and conditions are intended for its benefit and to the extent permitted by law.


                                       51
<PAGE>   59

                             STOCK OPTION AGREEMENT


     As a condition and inducement to Affymetrix' entering into the merger
agreement, Genetic MicroSystems granted to Affymetrix an option to purchase
shares of its common stock up to 19.9% of its currently outstanding capital
stock pursuant to a stock option agreement that was entered into on September
10, 1999. This section of this document describes certain aspects of the stock
option agreement, including material provisions of the stock option agreement.
The following description of the stock option agreement is not complete and is
qualified in its entirety by reference to the stock option agreement attached to
this document as Appendix B and incorporated in this document by reference. All
Genetic MicroSystems stockholders are urged to read the stock option agreement
carefully and in its entirety.


TERMS OF THE OPTION

NUMBER OF SHARES AND EXERCISE PRICE

     Under the stock option agreement, Genetic MicroSystems has granted to
Affymetrix an option to purchase shares of its common stock up to 19.9% of the
outstanding capital stock of Genetic MicroSystems at an exercise price per share
equal to $21.50.


     In the event of any change in the number of issued and outstanding shares
of capital stock of Genetic MicroSystems, the number of shares subject to the
stock option and the purchase price per share shall be appropriately adjusted to
preserve fully the economic benefits provided under the stock option agreement.


EXERCISE RIGHTS

     Affymetrix may exercise the stock option if:

     - any of the three triggering events described in the first paragraph under
       "Termination Fee and Expense Reimbursement" occurs; or


     - Genetic MicroSystems notifies Affymetrix that it received a superior
       proposal and Affymetrix notifies Genetic MicroSystems that it does not
       intend to match that acquisition proposal.



CANCELLATION OF OPTION FOR CASH



     The stock option agreement further provides that at any time the option is
exercisable, Affymetrix may elect to exercise its right to require Genetic
MicroSystems to pay to Affymetrix an amount in cash in exchange for the
cancellation of the option with respect to such number of shares as Affymetrix
specifies. This cash amount is equal to such number of shares multiplied by the
difference between the highest price per share of Genetic MicroSystems common
stock paid or proposed to be paid by any person pursuant to an acquisition
proposal and $21.50.


                                       52
<PAGE>   60

EXPIRATION


     If the stock option has not been exercised, the stock option agreement will
expire upon the earliest of:


     - the effective time of the merger;


     - twelve months after the date of termination of the merger agreement
       pursuant to a superior proposal which is not met by Affymetrix or if the
       Genetic MicroSystems board of directors withdraws or adversely modifies
       its recommendation of the merger; and


     - thirty days following the termination or the merger agreement for any
       reason other than those described above.

REPURCHASE AT THE OPTION OF GENETIC MICROSYSTEMS

     Pursuant to the stock option agreement, Genetic MicroSystems has the right
to repurchase any shares of Genetic MicroSystems common stock purchased by
Affymetrix pursuant to the stock option for a period of 180 days after each date
on which the stock option is exercised. The price per share Genetic MicroSystems
will pay upon a repurchase event is equal to the purchase price paid by
Affymetrix.

LIMITATION OF PROFIT


     Affymetrix' total profit under the stock option agreement together with the
amount of any termination and expense fee paid by Genetic MicroSystems to
Affymetrix pursuant to the merger agreement will not exceed $5,000,000.


EFFECT OF STOCK OPTION AGREEMENT


     The stock option agreement increases the likelihood that the merger will be
consummated under the terms of the merger agreement. The stock option agreement
could have the effect of making an acquisition or other combination of Genetic
MicroSystems by or with a third party more costly because of the need in any
such transaction to acquire, account for or pay the price of the stock option
shares that would be issued under the stock option agreement. Affymetrix and
Genetic MicroSystems also believe that the exercise of the stock option could
prohibit any other acquiror of Genetic MicroSystems during the next two years
from accounting for the acquisition by using the pooling-of-interests accounting
method. Accordingly, the stock option agreement may discourage a third party who
might be interested in effecting such an acquisition or combination from
considering or proposing the transaction or may cause a third party to offer to
pay a lower price than the third party would have proposed if
pooling-of-interest accounting were available. In addition, Affymetrix would
have a significant stake in Genetic MicroSystems if it exercised the stock
option and held the stock.


                                       53
<PAGE>   61

                                ESCROW AGREEMENT


     This section of this document describes certain aspects of the escrow
agreement, including material provisions of the escrow agreement. The following
description of the escrow agreement is not complete and is qualified in its
entirety by reference to the escrow agreement attached to this document as
Appendix C and incorporated in this document by reference. All Genetic
MicroSystems stockholders are urged to read the escrow agreement carefully and
in its entirety.



     Pursuant to the terms of the escrow agreement, Affymetrix will deposit 10%
of the aggregate merger consideration on a pro-rata per stockholder basis, for a
period not to exceed one year, with Bank One Trust Company, NA, as escrow agent.
The shares of Affymetrix common stock are reserved for the purpose of satisfying
the indemnification obligations owed to Affymetrix by Jean Montagu, who will
serve as stockholder representative under the escrow agreement, and the other
stockholders of Genetic MicroSystems. Five business days after the one-year
anniversary of the effective date of the merger, shares of Affymetrix common
stock that have not been used to satisfy claims will be will be distributed by
the escrow agent to the stockholders of Genetic MicroSystems based on each
stockholder's ownership percentage in Genetic MicroSystems. The escrow agreement
also provides that Affymetrix can instruct the escrow agent not to distribute
the escrowed shares until any unsatisfied indemnification claim has been
resolved.



     Affymetrix must pay to the escrow agent any cash or stock dividends and
other distributions with respect to the shares of Affymetrix common stock held
in the escrow account. The escrow agent will only retain in the escrow account
any dividends and distributions declared by reason of any reclassification,
recapitalization, stock split or combination, exchange or readjustment of
Affymetrix common stock. The escrow agent will distribute all other cash or
stock dividends on the shares of Affymetrix common stock to the stockholders of
Genetic MicroSystems based on the relative ownership percentage of each
stockholder.



     If Affymetrix believes it is entitled to payment for an indemnification
claim, it must file a certificate signed by its president or any of its
vice-presidents stating that claim. Unless the stockholder representative
objects within fifteen business days after the escrow agent and stockholder
representative receive that certificate, the escrow agent will pay Affymetrix'
claim on the fifteenth business day after its receipt of Affymetrix'
certificate. On that day, the escrow agent will deliver to Affymetrix that
number of shares of Affymetrix stock equal to the amount obtained by dividing
the amount sought under the indemnity by the closing price on the NASDAQ
National Market of Affymetrix stock on the closing date of the merger.



     If the stockholder representative objects to any Affymetrix claim in a
timely manner as detailed in the escrow agreement, the parties will endeavor in
good faith to agree on the amount that Affymetrix is entitled to recover from
the escrow account or have that amount determined by a court of competent
jurisdiction.


     Jean Montagu, as stockholder representative, will not receive a fee for his
services. He may resign on thirty days written notice to the parties to the
escrow agreement, or he may be removed by the stockholders of Genetic
MicroSystems. The stockholder representative is indemnified by the stockholders
of Genetic MicroSystems for losses and liabilities incurred without gross
negligence or bad faith on the part of the stockholder representative.

     Under the escrow agreement, no action may be taken or omitted to the extent
that such action or omission would result in the merger not qualifying for
pooling-of-interests accounting treatment.

                                       54
<PAGE>   62

                         STOCKHOLDER VOTING AGREEMENTS

     As a condition and inducement to Affymetrix' entering into the merger
agreement, Affymetrix entered into stockholder voting agreements with the
following six stockholders of Genetic MicroSystems:

     - Jean Montagu, the Chairman of the board of directors, Chief Executive
       Officer and founder of Genetic MicroSystems;

     - Dominic Montagu, family member of the Chairman of the board of directors,
       Chief Executive Officer and founder of Genetic MicroSystems;

     - Sasha Montagu, family member of the Chairman of the board of directors,
       Chief Executive Officer and founder of Genetic MicroSystems;


     - Stanley Rose, executive officer -- Vice President, Chief Operating
       Officer and Director of Genetic MicroSystems;



     - Peter Honkanen, executive officer -- Vice President of Engineering and
       Director of Genetic MicroSystems; and


     - Myles L. Mace, Jr., executive officer -- Vice President of Technology
       Developments of Genetic MicroSystems.


     This section of this document describes certain aspects of the stockholder
voting agreements, including material provisions of the stockholder voting
agreements. The following description of the stockholder voting agreements is
not complete and is qualified in its entirety by reference to the form of
stockholder voting agreement attached to this document as Appendix D and
incorporated in this document by reference.


GENERAL


     On September 10, 1999, contemporaneously with the execution and delivery of
the merger agreement, Affymetrix and the six stockholders listed above entered
into stockholder voting agreements pursuant to which each stockholder agreed,
among other things:


     - to vote all of the shares of Genetic MicroSystems over which the
       stockholder has voting power in favor of the merger agreement and the
       merger and any other transaction contemplated by the merger agreement;
       and


     - to vote all of the shares of Genetic MicroSystems over which the
       stockholder has voting power against:



        - any proposal that would constitute an acquisition proposal,



        - any amendment to the organizational documents of Genetic MicroSystems
          and



        - any other amendment, proposal or transaction involving Genetic
          MicroSystems, which amendment or other proposal or transaction would
          in any manner impede, frustrate, prevent or nullify the merger or
          which is reasonably likely to result in any of the conditions to
          Genetic MicroSystems' obligations under the merger agreement not being
          fulfilled; and


     - to grant to Affymetrix, an irrevocable proxy, or, if applicable, a power
       of attorney, and to irrevocably appoint Affymetrix, its attorney and
       proxy to vote all of the shares of Genetic

                                       55
<PAGE>   63

MicroSystems over which the stockholder has voting power with respect to
approval of the merger agreement at any meeting of the stockholders of Genetic
MicroSystems.

     Massachusetts law requires that the merger agreement be approved by the
affirmative vote of two-thirds of the shares of each class of stock of Genetic
MicroSystems. Together, the six stockholders listed above beneficially own and
have voting control over approximately 69.5% of the shares of Genetic
MicroSystems common stock and approximately 72% of the shares of Genetic
MicroSystems convertible preferred stock. Therefore, their shares represent more
than the number of votes necessary to adopt the merger agreement and approve the
merger.

TERMINATION

     The stockholder voting agreements provide that they will terminate upon the
earlier of:

     - the effective time of the merger; or

     - the termination of the merger agreement.

                    STOCK OWNERSHIP OF DIRECTORS, EXECUTIVE
                      OFFICERS AND PRINCIPAL STOCKHOLDERS


     Information concerning current directors and officers of Affymetrix,
executive compensation and ownership of Affymetrix common stock by management
and principal stockholders is contained in Affymetrix' proxy statement, dated
May 5, 1999, and is incorporated in this document by reference. See "Where You
Can Find More Information" on page 81.



     Genetic MicroSystems is a privately held corporation with fewer than ninety
stockholders and has no reporting obligation under the Securities Exchange Act
of 1934 or the rules and regulations of any exchange.



     The table on the following page sets forth beneficial ownership of Genetic
MicroSystems' capital stock as of November 12, 1999 by:


     - each person or entity known to Genetic MicroSystems to beneficially own
       5% or more of the outstanding shares of each class of Genetic
       MicroSystems' capital stock;

     - each of Genetic MicroSystems' directors;

     - Genetic MicroSystems' Chief Executive Officer and each of the other four
       most highly compensated executive officers of Genetic MicroSystems whose
       salary and bonus was greater than $100,000 in 1998; and

     - all directors and executive officers of Genetic MicroSystems as a group.

                                       56
<PAGE>   64

<TABLE>
<CAPTION>
                                                         SHARES OF SERIES A       SHARES OF SERIES B      PERCENT OF
                                 SHARES OF COMMON      CONVERTIBLE PREFERRED    CONVERTIBLE PREFERRED    OUTSTANDING
                                STOCK BENEFICIALLY       STOCK BENEFICIALLY       STOCK BENEFICIALLY       CAPITAL
                                    OWNED (1)                 OWNED(1)                 OWNED(1)            STOCK(2)
                              ----------------------   ----------------------   ----------------------   ------------
                              NUMBER OF   PERCENT OF   NUMBER OF   PERCENT OF   NUMBER OF   PERCENT OF    PERCENT OF
BENEFICIAL OWNER               SHARES       CLASS       SHARES       CLASS       SHARES       CLASS      TOTAL SHARES
- ----------------              ---------   ----------   ---------   ----------   ---------   ----------   ------------
<S>                           <C>         <C>          <C>         <C>          <C>         <C>          <C>
Jean Montagu................        --         --      1,500,000     75.00%       36,400(3)    8.43%        44.68%
Stanley D. Rose.............   300,000      29.80%       50,000(4)    2.44%       43,197(4)    9.09%        11.13%
Peter Honkanen..............   300,000      29.80%           --         --        25,000(4)    5.47%         9.38%
Myles L. Mace, Jr...........   100,000       9.93%       50,000       2.50%           --         --          4.36%
Dominic D. Montagu..........        --         --       100,000(5)    5.00%       14,260(6)    3.30%         3.32%
  823 Mendecino Ave.
  Berkeley, CA 94707
John N. Williams............        --         --       100,000       5.00%           --         --          2.91%
  84 Commonwealth Ave #4
  Boston, MA 02118
Sasha Montagu...............        --         --       100,000       5.00%           --         --          2.91%
  P.O. Box 962
  Whitefish, MT 59939
L. Robert Johnson...........    50,000       4.97%       50,000(7)    2.50%           --         --          2.91%
Stewart H. Greenfield.......        --         --       100,000       5.00%           --         --          2.91%
  274 Sturges Hwy.
  Westport, CT 06880
Gottlieb Knoch..............        --         --            --         --        35,294       8.17%         1.03%
  Taegerhalde 3
  Ch-8700
  Unsnacht, Switzerland
Jane L. Glassco.............        --         --            --         --        29,411       6.81%            *
  754 Euclid Avenue
  Toronto, Ontario
  Canada MGG 2V4
Andre Citroen...............        --         --            --         --        24,000       5.56%            *
  10 Green Street
  London, WIY 3RF
  United Kingdom
All current executive
  officers and directors as
  a group (8 persons).......   815,833(8)   79.01%     1,650,000(9)   80.49%     104,597(10)   20.91%       71.75%
</TABLE>

- -------------------------

  * Indicates less than 1%

 (1) Unless otherwise indicated, each stockholder has sole voting and investment
     power with respect to the shares listed in the table. The applicable
     percentage ownership for each stockholder of each class of capital stock of
     Genetic MicroSystems, as shown in this column, is based on (1) 1,006,702
     shares of common stock, (2) 2,000,000 shares of Series A convertible
     preferred stock, and (3) 431,977 shares of Series B convertible preferred
     stock of Genetic MicroSystems outstanding as of September 30, 1999, plus
     any shares subject to options or warrants held by the stockholder in
     question that are currently exercisable or exercisable within 60 days after
     September 30, 1999. Although the Series A convertible preferred stock and
     Series B convertible preferred stock is convertible into common stock, it
     is not reflected on an as-converted basis in the common stock column
     because, as a voting security, it is reflected in its own column.

 (2) The applicable percentage ownership for each stockholder, as shown in this
     column, is based on an aggregate amount of 3,438,679 shares of Genetic
     MicroSystems capital stock outstanding as of September 30, 1999, plus

                                       57
<PAGE>   65


     any shares subject to options or warrants held by the stockholder in
     question that are currently exercisable or exercisable within 60 days after
     November 1, 1999. The common stock, Series A convertible preferred stock
     and Series B convertible preferred stock vote together as a single class
     except as required by law or under Genetic MicroSystems' restated articles
     of organization. The merger is treated as a liquidation unless the holders
     of a majority of Series A convertible preferred stock, voting as a single
     class, elect not to treat it as a liquidation.


 (3) Jean Montagu shares voting and investment power with his wife with respect
     to the shares of Series B preferred stock held by Jean Montagu.


 (4) Represents shares that may be required within 60 days after November 1,
     1999 upon the exercise of outstanding warrants.


 (5) Consists of shares owned by Dominic Montagu and his wife in a trust for the
     benefit of their children, as to which Dominic Montagu disclaims beneficial
     ownership.

 (6) Includes 14,260 shares of Series B convertible preferred stock owned by or
     in trust for members of the immediate family of one stockholder, who
     disclaims beneficial ownership thereof.

 (7) L. Robert Johnson shares voting and investment power with his wife with
     respect to the shares of Series A convertible preferred stock held by L.
     Robert Johnson.


 (8) Includes 25,833 shares issuable upon exercise of outstanding stock options
     exercisable within 60 days after November 1, 1999.



 (9) Includes 50,000 shares issuable upon exercise of outstanding warrants
     exercisable within 60 days after November 1, 1999.



(10) Includes 68,197 shares issuable upon exercise of outstanding warrants
     exercisable within 60 days after November 1, 1999.


                   INTERESTS OF CERTAIN PERSONS IN THE MERGER


     In considering the recommendation of the Genetic MicroSystems board with
respect to the merger agreement and the transactions contemplated by the merger
agreement, stockholders of Genetic MicroSystems should be aware that members of
the management and board of directors of Genetic MicroSystems may have interests
in the merger that are different from, or in addition to, the interests of
stockholders of Genetic MicroSystems generally. All such interests are described
below, to the extent material, and Genetic MicroSystems believes that, except as
described below, such persons do not have any material interest in the merger
that is different from those of Genetic MicroSystems stockholders generally. The
Genetic MicroSystems board was aware of, and considered the interests of, its
directors and officers when it approved the merger agreement and the merger.


STOCK OWNERSHIP


     As of November 12, 1999, the directors and executive officers of Genetic
MicroSystems beneficially owned approximately 815,833 shares of Genetic
MicroSystems common stock, including 25,833 shares issuable upon exercise of
outstanding stock options exercisable within 60 days after November 12, 1999,
1,650,000 shares of Genetic MicroSystems Series A convertible preferred stock,
including 50,000 shares issuable upon exercise of outstanding warrants
exercisable within 60 days after November 12, 1999, and 104,597 shares of
Genetic MicroSystems Series B convertible preferred stock, including 68,197
shares issuable upon exercise of outstanding warrants exercisable within 60 days
after November 12, 1999. The directors and executive officers of Genetic
MicroSystems will receive the same consideration in connection with the merger
as other holders of Genetic MicroSystems common stock and options, Series A
convertible preferred stock and warrants, and Series B convertible preferred
stock and warrants, respectively.


                                       58
<PAGE>   66

NON-COMPETITION AGREEMENTS


     Affymetrix may, at its option, require that the following four senior
Genetic MicroSystems executives sign non-competition agreements as a condition
to the consummation of the merger:



     - Jean Montagu



     - Stanley D. Rose



     - Peter Honkanen



     - Michael Ryan


     The terms of these agreements have not yet been agreed to, but these
agreements will likely contain provisions whereby these individuals agree that:

     - for a period of time after the end of their employment by Affymetrix they
       will not directly or indirectly participate in a business or activity
       that competes with the business of Affymetrix or Genetic MicroSystems;

     - they will keep confidential commercially valuable information of
       Affymetrix; and

     - during the time they are employed by Affymetrix and for a period of time
       thereafter they will not directly or indirectly solicit employees of
       Affymetrix to leave the employ of Affymetrix, hire any former employee of
       Affymetrix within twelve months of the end of their employment with
       Affymetrix, solicit business from customers of Affymetrix, interfere with
       Affymetrix' relationship with any other person or disparage Affymetrix,
       its affiliates or employees.

     These individuals will not receive any consideration for entering into the
non-competition agreements other than the Affymetrix stock issued to them in the
merger.

1998 STOCK PLAN


     As of November 12, 1999, the directors and executive officers of Genetic
MicroSystems held stock options or warrants exercisable within 60 days after
November 12, 1999, to purchase 25,833 shares of Genetic MicroSystems common
stock, 50,000 shares of Genetic MicroSystems Series A convertible preferred
stock, and 68,197 shares of Genetic MicroSystems Series B convertible preferred
stock. At the effective time of the merger, each option and warrant, including
the stock options and warrants held by Genetic MicroSystems' executive officers
and directors, will convert into an option or warrant to acquire the number of
shares of Affymetrix common stock that the holder would have received in the
merger if the holder had exercised the option or warrant in full immediately
prior to the closing of the merger and the exercise price will be adjusted
appropriately. The number of shares of Affymetrix common stock that the new
Affymetrix option or warrant will be exercisable for and the exercise price of
the new Affymetrix option or warrant will reflect the exchange ratio. Affymetrix
has agreed to file with the Securities and Exchange Commission, not later than
60 days after the closing of the merger, a registration statement on Form S-8 or
other appropriate form under the Securities Act of 1933 to register the shares
of Affymetrix common stock issuable upon exercise of the options of Affymetrix
exchanged for Genetic MicroSystems options.


                                       59
<PAGE>   67

EMPLOYMENT CONTRACTS, TERMINATION OF EMPLOYMENT AND CHANGE-IN-CONTROL
ARRANGEMENTS

     On May 19, 1998, Genetic MicroSystems entered into an executive severance
agreement with Peter Lewis, Chief Financial Officer of Genetic MicroSystems. The
severance agreement provides that if within one year of a "change of control,"
Mr. Lewis' employment is terminated without "cause," as defined in the severance
agreement, or if Mr. Lewis terminates his employment for "good reason," as
defined in the severance agreement, Mr. Lewis will become entitled to:

     - receive severance compensation equal to the amount of his base salary at
       the time of termination, and


     - will be eligible to continue to participate in all benefit plans he was
       entitled to receive before his termination.


     The merger constitutes a "change of control" under Mr. Lewis' severance
agreement.

RESTRICTED STOCK AGREEMENTS

     Genetic MicroSystems has entered into restricted stock agreements with the
following directors and officers of Genetic MicroSystems:

     - Peter Honkanen

     - Peter Lewis

     - L. Robert Johnson


     Under the terms of the restricted stock purchase agreements, some or all of
the shares of Genetic MicroSystems common stock held by these individuals are
subject to repurchase by Genetic MicroSystems in the event that the individual's
employment or involvement with Genetic MicroSystems is terminated. The
restricted stock purchase agreements provide that upon an "acquisition event,"
the number of shares of Genetic MicroSystems common stock then subject to
repurchase by Genetic MicroSystems will become fully vested and released from
any repurchase right by Genetic MicroSystems. Genetic MicroSystems and
Affymetrix believe that the merger constitutes an acquisition event of Genetic
MicroSystems for purposes of the restricted stock agreements. Upon approval of
the merger, the vesting will be accelerated to the extent provided for in the
restricted stock agreements. On November 12, 1999, the above listed persons held
a total of 380,000 shares of Genetic MicroSystems common stock.


OWNERSHIP AND VOTING OF STOCK


     As of November 12, 1999, directors and executive officers of Genetic
MicroSystems and their affiliates may be deemed to have beneficial ownership of
approximately 79.01% of the outstanding shares of Genetic MicroSystems common
stock including outstanding stock options exercisable within 60 days after
November 12, 1999, approximately 80.49% of the shares of outstanding Series A
convertible preferred stock including outstanding warrants exercisable within 60
days after September 30, 1999, and approximately 20.91% of the outstanding
shares of Series B convertible preferred stock including outstanding warrants
exercisable within 60 days after November 12, 1999. These directors and
executive officers may be deemed to have beneficial ownership either by
themselves or with others. The following directors and executive officers of
Genetic MicroSystems have agreed in stockholder voting agreements with
Affymetrix to vote all of the outstanding shares of


                                       60
<PAGE>   68


Genetic MicroSystems stock, over which they have voting control, to be voted in
favor of adoption of the merger agreement:



     - Jean Montagu



     - Stanley Rose



     - Peter Honkanen



     - Myles L. Mace, Jr.



     For more detailed information concerning the stockholder voting agreements,
see "Stockholder Voting Agreements" on page 55.


                                       61
<PAGE>   69

          GENETIC MICROSYSTEMS MANAGEMENT'S DISCUSSION AND ANALYSIS OF
               THE FINANCIAL CONDITION AND RESULTS OF OPERATIONS

OVERVIEW

     Genetic MicroSystems was incorporated on August 7, 1997 to develop,
manufacture and sell a new generation of enabling products for genomics research
and drug discovery. Genetic MicroSystems was a development-stage company until
the commencement of substantial operations in 1998.

IMPACT OF YEAR 2000


     Genetic MicroSystems is assessing the potential impact of the year 2000
computer issues with regards to its systems and other aspects of its operations
dependent upon automation or computerized operation. Genetic MicroSystems has
initiated the assessment process and is expected to complete the project by year
end. The assessment will also include an analysis of certain third party
suppliers. Expenditures to date have not been material and are not expected to
be material based upon the information gathered to date. While Genetic
MicroSystems believes that the year 2000 issue will not pose significant
operational problems for its computer systems or other critically dependent
equipment, contingency plans may be developed in an attempt to minimize the
potential disruption on business, should an issue be identified.


RESULTS OF OPERATIONS

SIX MONTHS ENDED JULY 3, 1999 COMPARED TO SIX MONTHS ENDED JUNE 30, 1998

     Revenues for the first six months of 1999 were $5,081,572 as compared to no
revenue in the previous year's comparable period. The increase in revenue was
due to growing demand for arrayer and array scanner products which Genetic
MicroSystems began to ship during the fourth quarter of 1998.

     Genetic MicroSystems' gross margin for the period was $1,928,481 or 38.0 %
of revenues. This percentage was negatively impacted by inefficiencies
associated with the start-up of manufacturing and a mix of market seeding units
at low average unit price.

     Total selling, general and administrative expenses were $1,984,137 for the
first six months of 1999 versus $705,615 in the previous period. The growth in
expense is a function of building out of the infrastructure of Genetic
MicroSystems and the hiring of a direct sales force. Direct sales headcount was
8 as of July 3, 1999 as compared to zero in the previous period.

     Research and development expenses, for the first six months of 1999 were
$1,381,309, a growth of 29% over the $1,070,532 of spending in 1998. The
increase was primarily due to a continued expansion of the research and
development staff.

     During the period Genetic MicroSystems recorded $64,387 of net interest
income compared with $17,975 in the previous period. The growth in interest
income was a function of the larger cash equivalents position in 1999 as a
result of a Series B preferred stock equity offering in December of 1998 and
January of 1999. A loss on the sale of securities of $664,505 was recorded in
the six months ended June 30, 1998. Genetic MicroSystems did not record any
income tax benefit related to its losses in 1999, given the uncertainty
regarding its ability to generate taxable income in future year. The income tax
benefit of $808,411 recorded during the 6 months ended June 30, 1998, reflects
the income tax benefit associated with losses generated during 1998 which were
used to offset income generated from the sale of available for sale securities.

                                       62
<PAGE>   70

     The net loss and comprehensive net loss for the six months ended July 3,
1999 was $1,372,578 or $(1.36) per basic and diluted share. This compares with a
$1,614,266 net loss and a $972,489 comprehensive net loss in the comparable
period of 1998. The difference between the net loss and comprehensive net loss
in 1998 was due to the unrealized gains on available for sale securities during
the 6 months ended June 30, 1998. During 1998 Genetic MicroSystems sold all of
its investment securities. The net loss per basic and diluted share was $(10.35)
and the comprehensive net loss per basic and diluted share was $ (6.24) for the
six months ended June 30. 1998.

YEAR ENDED DECEMBER 31, 1998 COMPARED TO PERIOD FROM INCEPTION (AUGUST 7, 1997)
TO DECEMBER 31, 1997

     Revenues for 1998 were $387,605 versus no revenue in the previous year's
comparable period. The increase in revenue was due to the initial demand for
arrayer and array scanner products which Genetic MicroSystems began to ship in
the fourth quarter of 1998.

     Genetic MicroSystems' gross margin for the period was $20,000 or 5.2% of
revenues. This percentage was negatively impacted by inefficiencies associated
with the start-up of manufacturing.

     Total selling general and administrative expenses were $1,877,541 for 1998
versus $59,159 in the previous period. The growth in expense is a function of
building out of the infrastructure of Genetic MicroSystems.

     Research and development expenses for 1998 were $2,479,915 compared to
$421,694 of spending in 1997. The increase was primarily due to a continued
expansion of the research and development staff as well as a full year of
operations.

     During the period Genetic MicroSystems recorded $63,172 of net interest
income compared with none in the previous period. The growth in interest income
was a function of the larger cash equivalents position in 1998 as a result of
Genetic MicroSystems' sale of available for sale securities and proceeds from
the sale of Series A preferred stock.


     A loss on the sale of securities of $(664,505) was recorded in the year
ended December 31, 1998. The income tax benefit of $1,268,616 recorded during
1998, reflects the income tax benefit associated with losses generated during
1998 which were used to offset income generated from the sale of available for
sale securities.


     The net loss for the year ended December 31, 1998 was $(3,670,173) and the
comprehensive net loss was $(3,028,396). This compares with a $(253,771) net
loss and a $(895,548) comprehensive net loss in the comparable period of 1998.
For the year ended December 31, 1998, the net loss per basic and diluted share
was $(6.21) and the comprehensive net loss per basic and diluted share was
$(5.12). This compares to a net loss per basic and diluted share of $(25.38) and
the comprehensive net loss per basic and diluted share of $(89.55) for the 1997
period.

FINANCIAL CONDITION

     Since inception Genetic MicroSystems has financed its operations and growth
through the contributions of the founder in the form of equity securities, the
sale of Series A and Series B preferred stock and the sale of common stock
purchase rights to Takara Shuzo, a strategic partner.

     In the first six months of 1999, Genetic MicroSystems used $2,311,930 of
cash in operating activities due primarily to the loss from operations as well
as the increase in accounts receivable and inventories as shipments commenced.
The completion of the Series B preferred stock offering in January 1999
generated $709,184 of cash, more than offsetting the capital expenditures of
$237,685 in 1999.

                                       63
<PAGE>   71

     At July 3, 1999, Genetic MicroSystems had $2,526,577 of cash and cash
equivalents. Genetic MicroSystems believes that these capital resources are
sufficient to finance operations and capital expenditures through the end of the
year. Genetic MicroSystems also believes that it currently has the potential to
access sufficient additional capital resources to finance operations and capital
expenditures for the next 12 months. A deterioration in the business prospects
of Genetic MicroSystems or the financial markets, among other things, could
adversely affect the ability of Genetic MicroSystems to access additional
capital.

                                       64
<PAGE>   72

                    DESCRIPTION OF AFFYMETRIX CAPITAL STOCK

     The following summary is a description of the material terms of Affymetrix
capital stock, does not purport to be complete and is subject in all respects to
the applicable provisions of the Delaware General Corporation Law, Affymetrix'
certificate of incorporation and Affymetrix' bylaws, all of which are on file
with the SEC.

AUTHORIZED CAPITAL STOCK

     Affymetrix' authorized capital stock consists of 75,000,000 shares of
common stock, par value $0.01 per share, and 5,000,000 shares of preferred
stock, par value $0.01 per share, of which 1,634,522 are designated Series AA
preferred stock.

PREFERRED STOCK


     As of November 9, 1999, no shares of Series AA preferred stock were
outstanding. Pursuant to the Affymetrix rights agreement referred to below,
Affymetrix may designate a series of preferred securities entitled "Series B
Junior Participating Preferred Stock" for issuance upon the exercise of the
rights distributed to holders of Affymetrix stock pursuant to the Affymetrix
rights agreement. See "Description of the Capital Stock -- Rights Agreement" on
page 68.


SERIES AA PREFERRED STOCK

     DESIGNATION AND AMOUNT.  The authorized number of shares of Series AA
preferred stock, par value $0.01 per share, is 1,634,522. No shares of Series AA
preferred stock are currently outstanding.


     RANK.  With respect to dividend rights and rights on liquidation or
dissolution, the Series AA preferred stock ranks senior to Affymetrix common
stock and is subject to the rights of any series of preferred stock that may
from time to time come into existence.



     DIVIDENDS.  The holders of Series AA preferred stock are entitled to
receive cumulative dividends payable in cash prior and in preference to any
dividends paid to holders of common stock at the rate of $1.99 per share payable
in two equal installments on June 30 and December 31 of each year. These
dividends accrue on each share of Series AA preferred stock whether or not
earned or declared from the date on which the Series AA preferred stock was
first issued. Holders of Series AA preferred stock are also entitled to receive
an amount equal to any cash dividend paid to holders of common stock.



     LIQUIDATION RIGHTS.  In the event of a liquidation or dissolution of
Affymetrix, each holder of Series AA preferred stock is entitled to receive a
liquidation preference prior and in preference to any payments made to holders
of common stock. This preference is an amount per share equal to the sum of:


     - $30.59 for each outstanding share of Series AA preferred stock;

     - accrued but unpaid dividends on each share of Series AA preferred stock;
       and

     - a per share amount equal to the difference obtained by subtracting:

       - the product of ten percent of the annual per share dividend multiplied
         by a fraction, the numerator of which is the number of days elapsed
         since the date on which the first share of Series AA preferred stock
         was first issued and the denominator of which is 365, from

       - the annual per share dividend.

                                       65
<PAGE>   73

     After the payment, holders of Affymetrix common stock are entitled to
receive an amount per share equal to the quotient obtained by dividing:

     - the per share Series AA preferred stock liquidation preference by

     - the number of shares of common stock into which one share of Series AA
       preferred stock could then be converted.

     Any remaining assets would be distributed ratably to the holder of
Affymetrix common stock and holders of Series AA preferred stock.

     REDEMPTION.  Series AA preferred stock can be redeemed at the election of
Affymetrix or at the election of the holders of the Series AA preferred stock.

     Redemption at the Option of Affymetrix

     Subject to the rights of series of preferred stock that may from time to
time come into existence:

     - On or prior to March 9, 2001, Affymetrix may, at the option of the board
       of directors, redeem in whole or in part the Series AA preferred stock by
       paying in cash a sum equal to:

       - $30.59, as adjusted for any stock splits, stock dividends,
         combinations, recapitalizations or the like, plus

       - accrued but unpaid dividends on such share;

     provided that the closing sale price of this Affymetrix' common stock on
     the NASDAQ National Market, or any other national securities exchange on
     which the common stock is then listed, has been at or above $52.00, as
     adjusted for any stock splits, stock dividends, combinations,
     recapitalizations or the like, for twenty of thirty consecutive trading
     days prior to the applicable redemption date.

     - After March 9, 2001, Affymetrix may, at the option of the board of
       directors, redeem in whole or in part the Series AA preferred stock by
       paying in cash a sum equal to the Series AA liquidation preference
       described above.

     These redemptions will be made on a pro rata basis among the holders of the
Series AA preferred stock in proportion to the number of shares of Series AA
preferred stock then held, and each holder of Series AA preferred stock may, at
any time after notice by the corporation of its intention to redeem shares and
up to two trading days prior to the redemption, convert shares of Series AA
preferred stock into shares of Affymetrix common stock pursuant to the
conversion procedures described below. If Affymetrix has insufficient funds to
redeem all outstanding Series AA preferred stock, it must immediately redeem the
remaining shares of Series AA preferred stock as soon as funds become legally
available to effect the redemption.

     Redemption At the Option of the Stockholders

     Subject to the rights of series of preferred stock that may from time to
time come into existence, at any time on or after March 9, 2005, the holders of
not less than a majority of the then outstanding Series AA preferred stock can
request that a specified percentage of the holders' shares of Series AA
preferred stock be redeemed. Concurrently with surrender by the holders of the
certificates representing the shares, Affymetrix will, to the extent it may
lawfully do so, redeem the number of shares specified in the request on a pro
rata basis among the holders of the Series AA preferred stock

                                       66
<PAGE>   74

in proportion to the number of shares of Series AA preferred stock proposed to
be redeemed. Affymetrix will pay in cash a redemption price equal to:

     - $30.59 per share of Series AA preferred stock, as adjusted for any stock
       splits, stock dividends, recapitalizations or the like, plus

     - accrued but unpaid dividends on that share.

Affymetrix, however, is not required to redeem more than 817,261 shares of
Series AA preferred stock, as adjusted for any stock splits, stock dividends,
recapitalizations or the like, during any twelve-month period. If Affymetrix has
insufficient funds to redeem all outstanding Series AA preferred stock, it must
immediately redeem the remaining shares of Series AA preferred stock as soon as
funds become legally available to effect the redemption.

     CONVERSION RIGHTS.  Each share of Series AA preferred stock is convertible
into Affymetrix common stock at the option of the holder of the shares from the
time of issuance up to two days prior to an announced redemption date. Upon an
election to convert, that holder's shares of Series AA preferred stock will be
converted into that number of shares of Affymetrix common stock equal to:

     - $30.59, as ratably adjusted for any stock splits, stock dividends,
       combinations, recapitalizations or the like with respect to Series AA
       preferred stock, divided by

     - $39.77, as ratably adjusted for any stock splits, stock dividends,
       combinations, recapitalizations or the like with respect to Affymetrix
       common stock.

     OTHER DISTRIBUTIONS.  If Affymetrix declares a distribution payable in
securities of another company, evidences of indebtedness, assets excluding cash,
or other options or rights, the holders of Series AA preferred stock are
entitled to a proportionate share of that distribution as though they were
holders of the number of shares of Affymetrix common stock into which their
Series AA preferred stock is convertible.

     RECAPITALIZATION.  If the Affymetrix common stock is recapitalized, the
holders of Series AA preferred stock are entitled to receive, upon conversion of
their Series AA preferred stock to Affymetrix common stock, a number of shares
of Affymetrix common stock or other securities or property to which they would
have been entitled had they converted prior to the recapitalization.

     VOTING RIGHTS.  The holder of each share of Series AA preferred stock has
the right to one vote for each share of common stock into which the Series AA
preferred stock could then be converted at the record date for determination of
the stockholders entitled to vote. With respect to that vote, the holder will
have full voting rights and powers equal to the voting rights and powers of the
holders of common stock, and are entitled, notwithstanding any provision in
Affymetrix' charter, to notice of any stockholders' meeting in accordance with
Affymetrix' bylaws, and will be entitled to vote, together with holders of
common stock, with respect to any question upon which holders of common stock
have the right to vote and otherwise as required by law. Fractional votes will
not, however, be permitted and any fractional voting rights available on an
as-converted basis, after aggregating all shares into which shares of Series AA
preferred stock held by each holder could be converted, will be rounded to the
nearest whole number, with one-half being rounded upward.

OTHER SERIES OF PREFERRED STOCK

     Affymetrix' board is authorized to issue shares of preferred stock, in one
or more series, and to fix for each series the rights, privileges, preferences
and restrictions, including dividend rights, conversion rights, voting terms,
terms of redemption, liquidation preferences, and the number of

                                       67
<PAGE>   75

shares constituting any series or the designation of series, as are permitted by
the Delaware General Corporation Law.


     As of the date of this document, no shares of any other series of
Affymetrix preferred stock are outstanding. Pursuant to the Affymetrix rights
agreement referred to below, Affymetrix may designate a series of preferred
securities entitled "Series B Junior Participating Preferred Stock" for issuance
upon the exercise of the rights distributed to holders of Affymetrix stock
pursuant to the Affymetrix rights agreement. See "Description of the Capital
Stock -- Rights Agreement" on this page.


COMMON STOCK


     As of November 12, 1999, approximately 25,932,000 shares of Affymetrix
common stock were outstanding. In addition, no shares of Affymetrix common stock
were held in the treasury of Affymetrix and 4,133,612 shares of Affymetrix were
reserved for issuance pursuant to Affymetrix' employee benefit plans.
Immediately following the merger, we expect approximately -- shares of
Affymetrix common stock will be outstanding and approximately -- shares of
Affymetrix common stock will be reserved for issuance pursuant to Affymetrix'
employee benefit plans.



     The holders of Affymetrix common stock are entitled to receive ratably,
from funds legally available for the payment, dividends when and as declared by
resolution of the Affymetrix board, subject to any preferential dividend rights
which may be granted to holders of any preferred stock authorized and issued by
the Affymetrix board. Affymetrix will not be able to pay any dividend or make
any distribution of assets on shares of common stock until dividends on shares
of Affymetrix Series AA preferred stock and on any other shares of Affymetrix
preferred stock then outstanding with dividend or distribution rights senior to
the common stock have been paid. In the event of a liquidation or dissolution of
Affymetrix, each share of Affymetrix common stock is entitled to receive, after
payment of liabilities and, after payment of a liquidation preference to the
holders of Series AA preferred stock, an amount per share equal to the quotient
obtained by dividing the per share Series AA preferred stock liquidation
preference by the number of shares of common stock into which one share of
Series AA preferred stock could then be converted. After this payment, any
remaining assets would be distributed ratably to the holders of Affymetrix
common stock and holders of Affymetrix Series AA preferred stock.


     Each holder of Affymetrix common stock is entitled to one vote for each
share of Affymetrix common stock held of record on the applicable record date on
all matters submitted to a vote of stockholders, including the election of
directors. Holders of Affymetrix common stock have no preemptive or conversion
rights or other subscription rights. No redemption or sinking fund provisions
apply to Affymetrix common stock. The outstanding shares of Affymetrix common
stock are, and the shares of Affymetrix common stock issued in connection with
the merger will be, duly authorized, validly issued, fully paid and
nonassessable.

     American Stock Transfer & Trust Company is the transfer agent and registrar
for Affymetrix common stock.

RIGHTS AGREEMENT

     On October 15, 1998, the board of directors of Affymetrix declared a
dividend of one right to purchase Series B Junior Participating Preferred Stock
of Affymetrix, par value $0.01 per share, for each outstanding share of common
stock of Affymetrix and a number of rights for each share of Series AA preferred
stock of Affymetrix equal to the number of shares of common stock of Affymetrix
into which such share of Series AA preferred stock was convertible on October
27, 1998. Each right entitles the holder to purchase from Affymetrix
one-thousandth of a share of Series B

                                       68
<PAGE>   76

Junior Participating Preferred Stock, at an exercise price of $125.00 per one
one-thousandth of a share of Series B Junior Participating Preferred Stock,
subject to adjustment. The description and terms of the rights are set forth in
a rights agreement, dated as of October 15, 1998, between Affymetrix and
American Stock Transfer & Trust Company, as rights agent. The rights are
initially represented only by the underlying certificates of Affymetrix common
stock or Series AA preferred stock, as the case may be, and do not trade
separately from the common stock or the Series AA preferred stock unless and
until the earlier of:

     - ten days following a public announcement that a person or group of
       affiliated or associated persons, otherwise known as acquiring persons,
       has acquired beneficial ownership of 15% or more in aggregate voting
       power of the outstanding shares of Affymetrix common stock and Series AA
       preferred stock; or

     - ten business days, or such later date as the board of directors of
       Affymetrix may fix by resolution, after the date a person or group
       commences, or announces an intention to make, a tender or exchange offer
       that would result in such person or group becoming the beneficial owners
       of 15% or more of the aggregate voting power of the outstanding shares of
       Affymetrix common stock and Series AA preferred stock.

     The purchase price payable, and the number of shares of Series B Junior
Participating Preferred Stock issuable upon exercise of the rights is subject to
adjustment from time to time to prevent dilution. Because of the nature of the
Series B Junior Participating Preferred Stock's dividend, liquidation and voting
rights, the value of each 1/1000 of a share of Series B Junior Participating
Preferred Stock would have economic and voting terms equivalent to one share of
Affymetrix common stock.

     In the event that any person or group either acquires or may acquire 15% of
the aggregate voting power of the Affymetrix common stock and Series AA
preferred stock, the rights attached to this person or group's shares and the
rights attached to shares they beneficially own become void. Each other holder
of a right will have the right to receive upon exercise of a right that number
of shares of Affymetrix common stock having a market value of two times the
exercise price of the right.

     In the event that, after a person or group has become an acquiring person
of 15% or more of the voting power of Affymetrix, Affymetrix is acquired in a
merger or similar form of business combination or the acquisition by such
acquiring person of 50% or more in aggregate voting power of the outstanding
shares of Affymetrix common stock and Series AA preferred stock, each holder of
a right, other than rights beneficially owned by an acquiring person which have
become void, will thereafter have the ability to exercise each right for that
number of shares of common stock of that acquiring person equal to two times the
market value of the exercise price.


     At any time after any person or group becomes an acquiring person and prior
to a merger or similar form of business combination or the acquisition by an
acquiring person of 50% or more in aggregate voting power of the outstanding
shares of Affymetrix common stock and Series AA preferred stock, the Affymetrix
board may exchange the rights, other than rights owned by an acquiring person
which have become void, in whole or in part, for shares of Affymetrix common
stock, Series B Junior Participating Preferred Stock, or a series of Affymetrix'
preferred stock having equivalent rights, preferences and privileges, at an
exchange ratio of one share of Affymetrix common stock, or a fractional share of
Series B Junior Participating Preferred Stock or other preferred stock, of
equivalent value, per right.


                                       69
<PAGE>   77

     Shares of Series B Junior Participating Preferred Stock purchasable upon
exercise of the rights will not be redeemable. Each share of Series B Junior
Participating Preferred Stock will be entitled, when, as and if declared, to a
minimum preferential quarterly dividend payment of the greater of:

     - $10 per share, and

     - an amount equal to one-thousandth of the dividend declared per share of
       Affymetrix common stock.

     In the event of liquidation, dissolution or winding up of Affymetrix, the
holders of the Series B Junior Participating Preferred Stock will be entitled to
a minimum preferential payment of the greater of:

     - $10 per share (plus any accrued but unpaid dividends); or

     - an amount equal to one thousandth of the liquidation payment made per
       share of Affymetrix common stock.

     Each share of Series B Junior Participating Preferred Stock will have
one-thousand votes, voting together with the Affymetrix common stock. Finally,
in the event of any merger, consolidation or other transaction in which
outstanding shares of Affymetrix common stock are converted or exchanged, each
share of Series B Junior Participating Preferred Stock will be entitled to
receive one-thousand times the amount received per share of Affymetrix common
stock.

     The rights expire on October 15, 2008, unless this expiration date is
advanced or extended or unless the rights are earlier redeemed or exchanged by
Affymetrix. Prior to the time that a person becomes an acquiring person,
Affymetrix may redeem the rights in whole, but not in part, for $0.01 per right,
or it may amend the rights agreement in any manner without the consent of the
holders of the rights. After the rights are no longer redeemable, however,
Affymetrix may, except with respect to the redemption price, amend the rights
agreement in any manner that does not adversely affect the interests of holders
of the rights.


     The rights will not prevent a takeover of Affymetrix. The rights, however,
may cause substantial dilution to a person or group that acquires 15% or more of
the common stock unless the rights are first redeemed by the Affymetrix board of
directors. Until a right is exercised or exchanged, that holder will have no
rights as an Affymetrix stockholder, including, without limitation, the right to
vote or to receive dividends.



     A copy of the rights agreement has been filed with the Securities and
Exchange Commission as an Exhibit to a Registration Statement on Form 8-A, dated
October 16, 1998. A description of the rights is available free of charge from
Affymetrix, see "Where You Can Get More Information" on page 81. This summary
description of the rights does not purport to be complete and is qualified in
its entirety by reference to the description of the rights contained in the
Registration Statement on Form 8-A, dated October 16, 1998, which is hereby
incorporated into this document by reference.


                                       70
<PAGE>   78

                        COMPARISON OF STOCKHOLDER RIGHTS

     As a result of the merger, holders of Genetic MicroSystems stock will
become holders of Affymetrix common stock. The following is a summary of certain
material differences between the rights of holders of Genetic MicroSystems
convertible preferred stock and common stock and the rights of holders of
Affymetrix common stock.

     The rights of Genetic MicroSystems stockholders are currently governed by
Genetic MicroSystems' articles of organization and bylaws and applicable
provisions of the Massachusetts Business Corporation Law. Affymetrix'
stockholders' rights are currently governed by Affymetrix' certificate of
incorporation and bylaws and applicable provisions of the Delaware General
Corporation Law.

     The following summary highlights important similarities and differences
between the rights of current holders of Affymetrix common stock and current
holders of Genetic MicroSystems stock. This summary does not purport to be a
complete discussion of the charters and bylaws of Genetic MicroSystems and
Affymetrix or the corporation laws of Massachusetts or Delaware. The discussion
of the Affymetrix charter and bylaws is qualified in its entirety by reference
to the Affymetrix charter and bylaws, copies of which are on file with the
Securities and Exchange Commission. The articles of Genetic MicroSystems are
publicly available from the Secretary of State of the Commonwealth of
Massachusetts.

                            AUTHORIZED CAPITAL STOCK


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix' charter authorizes Affymetrix     Genetic MicroSystems' articles authorize
to issue 80,000,000 shares of capital         Genetic MicroSystems to issue 7,636,353
stock, of which:                              shares of capital stock, of which:

- - 75,000,000 shares are designated common     - 5,000,000 shares are designated common
  stock, $0.01 par value per share; and         stock, no par value; and

- - 5,000,000 shares are designated             - 2,636,353 shares are designated
  preferred stock, $0.01 par value per          preferred stock, $0.01 par value per
  share; including 1,634,522 shares of          share; consisting of 2,054,000 shares of
  Series AA preferred stock, $0.01 par          Series A convertible preferred stock,
  value per share. Pursuant to the              $0.01 par value per share, and 582,353
  Affymetrix rights agreement referred to       shares of Series B convertible preferred
  above, Affymetrix may designate a series      stock, $0.01 par value per share.
  of preferred securities entitled "Series
  B Junior Participating Preferred Stock"
  for issuance upon the exercise of the
  rights distributed to holders of
  Affymetrix stock pursuant to the
  Affymetrix rights agreement. See
  "Description of the Capital
  Stock -- Rights Agreement" on page 68.
</TABLE>


                                PREFERRED STOCK

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix' board of directors is             Genetic MicroSystems preferred stock may
authorized to issue shares of preferred       be issued from time to time in one or more
stock in one or more series, and to fix
for each series the designations
</TABLE>

                                       71
<PAGE>   79


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
and relative powers, preferences,             series. The board may determine and fix
conversion or other rights, voting powers,    voting powers, full, limited or no voting
restrictions, limitations as to dividends,    powers, and such designations, preferences
qualifications, or terms or conditions of     and relative participating, optional or
redemption, as are permitted by the           other special rights, and qualifications,
Delaware General Corporation Law. To date,    limitations or restrictions thereof,
no shares of any series of Affymetrix         including without limitation, dividend
preferred stock other than Series AA          rights, special voting rights, conversion
preferred stock are authorized. Pursuant      rights, redemption privileges and
to the Affymetrix rights agreement            liquidation preferences, as shall be
referred to below, Affymetrix may             stated and expressed in resolutions all to
designate a series of preferred securities    the full extent permitted by the
entitled "Series B Participating Preferred    Massachusetts Business Corporation Law.
Stock" for issuance upon the exercise of      The resolutions providing for issuance of
the rights distributed to holders of          any series of preferred stock may provide
Affymetrix stock pursuant to the              that a new series is superior or rank
Affymetrix rights agreement. See              equally or be junior to the preferred
"Description of Affymetrix Capital Stock"     stock of any other series to the extent
beginning on page 65.                         permitted by the Massachusetts Business
                                              Corporation Law. Except as otherwise
                                              provided by Genetic MicroSystems, no vote
                                              of the holders of the Genetic MicroSystems
                                              preferred stock or Genetic MicroSystems
                                              common stock is a prerequisite to the
                                              issuance of any shares of any series of
                                              the preferred stock.
</TABLE>


                                   DIVIDENDS


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Delaware Law: Corporations generally are      Massachusetts Law: Corporations generally
permitted to declare and pay dividends out    are permitted to pay dividends if the
of surplus or out of net profits for the      action is not taken when the corporation
current and/or immediately preceding          is insolvent, does not render the
fiscal year, provided that dividends will     corporation insolvent, and does not
not reduce capital below the amount of        violate the corporation's articles of
capital represented by all classes of         organization. The directors of a
stock having a preference upon the            Massachusetts corporation may be jointly
distribution of assets. A corporation may     and severally liable to the corporation to
generally redeem or repurchase shares of      the extent that the directors authorize a
its stock if the redemption or repurchase     dividend when the corporation is insolvent
will not impair the capital of a              or where the amount of the dividend
corporation. The directors of a Delaware      exceeds the permissible amounts and the
corporation may be jointly and severally      excess amount not repaid to the
liable to the corporation for a willful or    corporation.
negligent violation of these provisions of
Delaware law.

     Affymetrix common stock: Subject to      Genetic MicroSystems common stock: Genetic
all the rights of the preferred stock,        MicroSystems' articles provide that
except as may be expressly provided with      dividends may be declared and paid on the
respect to the preferred stock, by law or     Genetic MicroSystems common stock from
by the board pursuant to Paragraph 5(1)(a)    funds lawfully available as determined by
of Article FIFTH of the charter, dividends    the board of directors. Dividends paid to
may be declared and paid or set apart for     holders of Genetic MicroSystems common
payment upon the Affymetrix common stock      stock are subject to any preferential
only out of any assets or funds of            dividend rights of any
</TABLE>


                                       72
<PAGE>   80


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix legally available for the          then outstanding Genetic MicroSystems
payment of dividends.                         preferred stock.

                                              Genetic MicroSystems preferred stock:
                                              During any fiscal year of the corporation,
                                              no dividends, other than dividends payable
                                              solely in shares of Genetic MicroSystems
                                              common stock, shall be paid or declared,
                                              and no other distributions shall be made,
                                              on or with respect to the Genetic
                                              MicroSystems common stock with one
                                              exception. Unless and until there shall
                                              have been paid, or declared and set aside
                                              for payment, during the fiscal year
                                              dividends with respect to each share of
                                              Series A convertible preferred stock in an
                                              amount equivalent to the amount per share
                                              to be paid as a dividend on the Genetic
                                              MicroSystems common stock, such equivalent
                                              amount payable in respect of each share of
                                              Series A convertible preferred stock will
                                              be determined by multiplying the amount
                                              per share of the dividend to be paid on
                                              the common stock by the number of shares
                                              of common stock into which each such share
                                              of Series A convertible preferred stock
                                              and convertible at the record date for the
                                              determination of stockholders entitled to
                                              the payment of such dividend.
</TABLE>


                                 VOTING RIGHTS


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix common stock: Holders are          Genetic MicroSystems common stock: Holders
entitled to one vote for each share held      are entitled to one vote for each share
at all meetings of stockholders and           held at all meetings of stockholders and
written actions in lieu of meetings. There    written actions in lieu of meetings. There
is no cumulative voting.                      is no cumulative voting.

                                              Genetic MicroSystems preferred stock: On
                                              all matters submitted to a vote of holders
                                              of Genetic MicroSystems common stock
                                              generally, each share of Series A
                                              convertible preferred stock or Series B
                                              convertible preferred stock will have the
                                              right to exercise the number of votes
                                              equal to the number of shares of common
                                              stock into which such share of Series A
                                              convertible preferred stock or Series B
                                              convertible preferred stock could be
                                              converted on the record date for
                                              determining stockholders having a right to
                                              vote on such matters, and, except as
                                              required by law,
</TABLE>


                                       73
<PAGE>   81

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
                                              the Series A convertible preferred stock,
                                              the Series B convertible preferred stock
                                              and the Genetic MicroSystems common stock
                                              will vote as a single class.
</TABLE>

                            MEETINGS OF STOCKHOLDERS

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix' charter and bylaws provide        Genetic MicroSystems' bylaws provide for
that special meetings of stockholders,        the call of a special meeting at any time
other than those required by statute, may     by the President or a majority of the
be called only by the Chairman of the         directors. Special meetings shall be
Board or the President or by the board of     called by the Clerk, or in the case of his
directors acting pursuant to a resolution     death, absence, incapacity or refusal, by
adopted by a majority of the total number     any other officer, upon written
of authorized directors whether or not        application of one or more stockholders
there exist any vacancies in previously       who hold at least one-tenth part in
authorized directorships.                     interest of the capital stock entitled to
                                              vote at such meeting, stating the time,
                                              place and purpose of the meeting.
Affymetrix' bylaws provide that an annual     The annual meeting of stockholders shall
meeting of the stockholders, for the          be held within six months after the end of
election of directors to succeed those        Genetic MicroSystems' fiscal year
whose terms expire and for the transaction    specified in the bylaws, at such date,
of such other business as may properly        hour and place as are fixed by the board
come before the meeting, shall be held at     of directors or the president. At such
11 a.m. on the first Tuesday of the fifth     annual meeting the stockholders shall
calendar month following the end of the       elect directors, hear the report of the
corporation's fiscal year or at such time     treasurer, and transact such other
as the board of directors shall each year     business as may properly come before the
fix, which date shall be within 13 months     meeting. In the event that no date for the
of the last annual meeting of the             annual meeting is established or if no
stockholders.                                 annual meeting is held in accordance with
                                              the foregoing procedures, a special
                                              meeting of the stockholders may be held in
                                              lieu of and for the purposes of the annual
                                              meeting with all the force and effect of
                                              an annual meeting and for such other
                                              purposes as may be specified in the notice
                                              of that special meeting.
</TABLE>

                    ACTION BY STOCKHOLDERS WITHOUT A MEETING


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Unless otherwise provided in the              Under Massachusetts law, any action to be
certificate of incorporation, Delaware law    taken by stockholders may be taken without
permits stockholders to take action           a meeting only by unanimous written
without a meeting, without prior notice       consent.
and without a vote, upon the written
consent of stockholders having not less
than the minimum number of votes that
would be necessary to authorize the
proposed
</TABLE>


                                       74
<PAGE>   82

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
action at a meeting at which all shares
entitled to vote were present and voted.

     Affymetrix' charter provides that any    Pursuant to the Genetic MicroSystems
action required or permitted to be taken      bylaws, any action required or permitted
by the stockholders of the corporation        to be taken by stockholders at a meeting
must be effected at a duly called annual      may be taken without a meeting if all
or special meeting of stockholders of the     stockholders entitled to vote on the
corporation and may not be effected by any    matter consent to the action in writing
consent in writing by such stockholders.      and the written consents are filed with
                                              the records of the meetings of
                                              stockholders.
</TABLE>

                               BOARD OF DIRECTORS

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix currently has nine directors.      Genetic MicroSystems currently has four
                                              directors.

     The authorized number of directors       The Genetic MicroSystems board of
cannot be less than six nor more than         directors consists of not less than three
eleven. Within these limits, the exact        nor more than fifteen directors, except
number of directors is set at nine. An        that whenever there are only two
indefinite number of directors may be         stockholders, the Genetic MicroSystems
fixed, or the definite number of directors    board of directors may consist of at
may be changed, by a duly adopted             least, but not be less than, two
amendment to the charter or by an             directors, and whenever there is only one
amendment to the bylaws duly adopted by       stockholder or prior to the issuance of
the stockholders or Affymetrix board of       any stock, the board may consist of at
directors.                                    least, but not less than, one director.
Whenever the authorized number of             The directors generally hold office until
directors is increased between annual         the next annual meeting of stockholders or
meetings of the stockholders, a majority      directors at which they are regularly
of the directors then in office have the      elected and until their successors are
power to elect such new directors for the     chosen and qualified.
balance of a term and until their
successors are elected and qualified. Any
decrease in the authorized number of
directors does not become effective until
the expiration of the term of the
directors then in office unless, at the
time of that decrease, there are vacancies
on the board of directors which are being
eliminated by the decrease.

     Subject to applicable law and to the     When there is a vacancy in the Genetic
rights of holders of any series of            MicroSystems board of directors, including
preferred stock with respect to that          a vacancy resulting from the enlargement
series of preferred stock, and unless the     of the board, the Genetic MicroSystems
Affymetrix board of directors otherwise       board of directors may fill that vacancy
determines, vacancies on the board of         by the affirmative vote of a majority of
directors (including without limitation       the directors then in office. Any vacancy
vacancies resulting from death,               in the Genetic MicroSystems board of
resignation, retirement, disqualification     directors may also be filled by the
from office or other cause) are
</TABLE>

                                       75
<PAGE>   83

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
filled only by a majority vote of the         stockholders at any regular or special
directors then in office, though less than    meeting unless that vacancy has been
a quorum, and directors so chosen will        previously filled by the Genetic
hold office for the unexpired term and        MicroSystems board of directors. Any
until his or her successor is duly elected    director so elected by the Genetic
or qualified. No decrease in the number of    MicroSystems board of directors or
authorized directors constituting the         stockholders to fill such vacancy will
entire Affymetrix board of directors          hold office only until the next meeting of
shortens the term of any incumbent            the stockholders or directors at which the
director.                                     office would regularly be filled and until
                                              a successor is chosen and qualified.

     The board of directors is elected at     The Genetic MicroSystems board of
each annual meeting of the Stockholders.      directors is elected at each annual
                                              meeting of the stockholders. Except as
                                              summarized above, the exact number of
                                              directors constituting the board is fixed
                                              at each annual meeting by the
                                              stockholders, provided that by vote of the
                                              stockholders at a special meeting called
                                              for the purpose the number of directors
                                              may be increased or decreased and provided
                                              further that by vote of a majority of the
                                              directors then in office, the number of
                                              directors may be increased. No vacancy
                                              shall be deemed to exist in the board
                                              unless and until the number of directors
                                              in office falls below the number so fixed.

At any meeting of the board of directors,     At any meeting of the Genetic MicroSystems
a majority of the total number of the         board of directors, a majority, or if the
whole Affymetrix board of directors           number of directors is an even number,
constitutes a quorum for all purposes. If     then one-half, of the directors then in
there is not a quorum at the meeting, a       office constitutes a quorum.
majority of those present may adjourn the
meeting to another place, date, or time,
without further notice or waiver thereof.

     The Affymetrix charter gives the         The Genetic MicroSystems articles and
Affymetrix board of directors broad           bylaws give the Genetic MicroSystems
authority, including authority to fix the     directors broad powers, including the
compensation of the directors. The            power to fix any fees or other
directors may be paid their expenses, if      compensation paid to directors and members
any, of attendance at each meeting of the     of the Genetic MicroSystems executive
board of directors or paid a stated salary    committee and any other committees, if
or paid other compensation as director. No    any, for their services to Genetic
such payment shall preclude any director      MicroSystems as the board may deem
from serving the corporation in any other     reasonable.
capacity and receiving compensation
therefor.
</TABLE>

                                       76
<PAGE>   84

                   INDEMNIFICATION OF DIRECTORS AND OFFICERS


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Under Delaware law, a director is not         Under Massachusetts law, a director is
exculpated from liability under provisions    generally not exculpated from liability
of the Delaware General Corporation Law       under provisions of the Massachusetts
relating to unlawful payments of dividends    Business Corporation Law relating to
and unlawful stock purchases or               unauthorized distributions and loans to
redemptions.                                  insiders.

     Delaware General Corporation Law         The Massachusetts Business Corporation Law
generally permits indemnification, or         provides that no indemnification may be
reimbursement, of directors and officers      provided with respect to any matter in
for expenses, judgments, fines and amounts    which the director or officer shall have
paid in settlement of claims incurred by      been adjudicated not to have acted in good
them by reason of their position with the     faith in the reasonable belief that his
corporation.                                  action was:

     The Delaware General Corporation Law     - in the best interest of the corporation,
permits indemnification only where there        or
has been a determination by a majority
vote of disinterested directors,              - to the extent that such matter relates
independent legal counsel, or the               to service with respect to any employee
stockholders that the person seeking            benefit plan, in the best interests of
indemnification acted in good faith and in      the participants or beneficiaries of
a manner he or she reasonably believed to       such employee benefit plan.
be in, or not opposed to, the best
interests of the corporation.

     The Delaware General Corporation Law     The Massachusetts Business Corporation Law
expressly does not permit a corporation to    does not explicitly address indemnifying
indemnify persons against judgments in        persons against judgments in actions
actions brought by or in the right of the     brought by or in the right of the
corporation, although it does permit          corporation. The previously discussed
indemnification in such situations if         standard applies to such cases.
approved by the Delaware Court of Chancery
and for expenses of such actions.

     Affymetrix' charter provides that, to    Genetic MicroSystems' articles provide
the fullest extent permitted by Delaware      that no director of the corporation shall
General Corporation Law, a director of the    be personally liable to the corporation or
corporation shall not be personally liable    its stockholders for monetary damages for
to the corporation or its stockholders for    breach of fiduciary duty as a director
monetary damages for breach of fiduciary      notwithstanding any provision of law
duty as a director, except for liability:     imposing such liability; provided,
                                              however, that this provision shall not
- - for any breach of the director's duty of    eliminate or limit the liability of a
  loyalty to the corporation or its           director, to the extent that such
  stockholders;                               liability is imposed by applicable law:
- - for acts or omissions not in good faith     - for any breach of the director's duty of
  or which involve intentional misconduct       loyalty to the corporation or its
  or a knowing violation of law;                stockholders;
- - under Section 174 of the Delaware           - for acts or omissions not in good faith
  General Corporation Law; or                   or which involve intentional misconduct or
                                                a knowing violation of law;
</TABLE>


                                       77
<PAGE>   85

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
- - for any transaction from which the          - under Section 61 or 62 or successor
  director derived an improper personal         provisions of the Massachusetts Business
  benefit.                                      Corporation Law; or
                                              - for any transaction from which the
                                                director derived an improper personal
                                                benefit.

     If the Delaware General Corporation      No amendment to or repeal of this
Law is amended to authorize corporate         provision of the Genetic MicroSystems
action further eliminating or limiting the    articles shall apply to or have any effect
personal liability of directors, then the     on the liability or alleged liability of
liability of a director of the corporation    any director for or with respect to any
shall be eliminated or limited to the         acts or omissions of such director
fullest extent permitted by the Delaware      occurring prior to such amendment or
General Corporation Law, as amended.          repeal.
</TABLE>

                        AMENDMENT OF CHARTER AND BYLAWS


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Affymetrix' charter provides that the         Genetic MicroSystems' articles authorize
Affymetrix board of directors is expressly    the Genetic MicroSystems board of
empowered to adopt, alter, amend or repeal    directors to make, amend or repeal the
bylaws of the corporation. Any adoption,      bylaws to the extent permitted by law.
alteration, amendment or repeal of the        Genetic MicroSystems' bylaws provide that
bylaws of the corporation by the              they may be amended or repealed and new
Affymetrix board of directors requires the    bylaws made either:
approval of a majority of the entire board
of directors. The stockholders also have      - by the stockholders at any meeting of
power to adopt, amend or repeal the bylaws      the stockholders by the affirmative vote
of the corporation; provided, however,          of the holders of at least a majority in
that in addition to any vote of the             interest of the capital stock then
holders of any class or series of stock of      outstanding and then entitled to vote,
the corporation required by law or by the       provided that notice of the proposed
charter, the affirmative vote of at least       alteration, addition, amendment or
a majority of the voting power of all the       repeal stating such change or the
then-outstanding shares of the capital          substance thereof shall have been given
stock of the corporation entitled to vote       in the notice of such meeting or in the
generally in the election of directors,         waiver of notice with respect to such
voting together as a single class, shall        meeting, or
be required to adopt, alter, amend or
repeal any provision of the corporation's     - by vote of a majority of the Genetic
bylaws.                                         MicroSystems board of directors then in
                                                office, except with respect to any
                                                provision as to which stockholder action
                                                is required by law, the articles, or the
                                                bylaws; provided that not later than the
                                                time of giving notice of the meeting of
                                                stockholders next following any such
                                                change in the bylaws by the directors,
                                                notice thereof shall be given to all
                                                stockholders entitled to vote on
                                                amending the bylaws.

     Pursuant to Delaware law, the charter    Massachusetts law requires a majority vote
of Affymetrix may be amended by a majority    to amend the articles for events, such as
vote                                          an
</TABLE>


                                       78
<PAGE>   86

<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
of the stockholders.                          increase in the authorized capital stock
                                              or a change in corporate name, but
                                              requires a two-thirds vote for other
                                              amendments such as a change in the nature
                                              of its corporate business, or to authorize
                                              the sale, mortgage, pledge, lease or
                                              exchange of all its property or assets
                                              unless the articles of organization
                                              provide for a lesser vote, not to be less
                                              than a majority of the shares entitled to
                                              vote.
</TABLE>

                                  TAKEOVER LAW


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
Section 203 of the Delaware General           The Massachusetts Business Combination
Corporation Law prohibits a corporation       statute provides that, if a person
which has securities traded on a national     acquires 5% or more of the outstanding
securities exchange, designated on the        voting stock of a Massachusetts
NASDAQ National Market or held of record      corporation without the approval of its
by more than 2,000 stockholders from          board of directors, that person will
engaging in various business combinations,    become an "interested stockholder" and he
including a merger, sale of substantial       or she may not engage in certain
assets, loan or substantial issuance of       transactions with the corporation for
stock, with an interested stockholder,        three years unless the:
defined generally as a person beneficially
owning 15% or more of the corporation's       - board of directors approves the
outstanding voting stock, or an interested      acquisition of stock or the transaction
stockholder's affiliates or associates,         prior to the time that the person became
for a three-year period beginning on the        an interested stockholder;
date the interested stockholder acquires
15% or more of the outstanding voting         - interested stockholder acquires 90% of
stock of the corporation. The restrictions      the outstanding voting stock of the
on business combinations do not apply if:       company, excluding voting stock owned by
                                                directors who are also officers and
                                                certain employee stock plans, in one
                                                transaction; or
                                              - transaction is approved by the board and
                                                by two-thirds of the outstanding voting
                                                stock not owned by the interested
                                                stockholder.
                                              This Massachusetts statute is inapplicable
                                              to this transaction, however, because
                                              Genetic MicroSystems has fewer than two
                                              hundred stockholders of record.
- - the board of directors gives prior
  approval to the transaction in which the
  15% ownership level is exceeded,

- - the interested stockholder acquires 85%
  or more of the corporation's outstanding
  stock in the same transaction in which
  the stockholder's ownership first
  exceeds 15%, excluding those shares
  owned by persons who are directors and
  also officers as well as by employee
  stock plans in which employees do
</TABLE>


                                       79
<PAGE>   87


<TABLE>
<CAPTION>
                AFFYMETRIX                               GENETIC MICROSYSTEMS
                ----------                               --------------------
<S>                                           <C>
  not have the right to determine
  confidentially whether shares held
  subject to the plan will be tendered in
  a tender or exchange offer, or

- - on or following the date on which the
  stockholder became an interested
  stockholder, the board of directors
  approves the business combination and
  the holders of at least two-thirds of
  the outstanding voting stock, excluding
  shares owned by the interested
  stockholder, authorize the business
  combination at a meeting of
  stockholders.

     Although a Delaware corporation may
elect, pursuant to its certificate or
bylaws, not to be governed by this
provision, the charter and the Affymetrix
bylaws do not contain these elections.

     The Delaware General Corporation Law     The Massachusetts Business Corporation Law
generally requires that mergers and           provides that a merger agreement must be
consolidations, and sales, leases or          approved by a vote of two-thirds of the
exchanges of all or substantially all of a    shares of each class of stock unless the
corporation's property and assets be          articles of organization of the
approved by the directors and by a vote of    corporation provide for a vote of a lesser
the holders of a majority of the              proportion but not less than a majority of
outstanding stock entitled to vote, though    shares outstanding and entitled to vote.
a corporation's certificate of                See "The Genetic MicroSystems Special
incorporation may require a                   Meeting -- Required Vote" on page 28 for a
greater-than-majority vote. Under the         discussion on the voting provisions in the
Delaware General Corporation Law, a           Genetic MicroSystems articles with respect
surviving corporation need not have           to the merger.
stockholder approval for a merger if:
- - each share of the surviving
  corporation's stock outstanding prior to
  the merger remains outstanding in
  identical form after the merger;

- - there is no amendment to its certificate
  of incorporation; and

- - the consideration going to stockholders
  of the non-surviving corporation is not
  common stock (or securities convertible
  into common stock) of the surviving
  corporation or, if it is such stock or
  securities convertible into such stock,
  the aggregate number of common shares
  actually issued or delivered, or
  initially issuable upon conversion does
  not exceed 20% of the shares of the
  survivor's common stock outstanding
  immediately prior to the effective date
  of the merger.
</TABLE>


                                       80
<PAGE>   88

                               VALIDITY OF SHARES


     The validity of the Affymetrix common stock to be issued in connection with
the merger will be passed upon by the General Counsel of Affymetrix. Certain tax
matters relating to the merger will be passed upon by Sullivan & Cromwell, New
York, New York, and Palmer & Dodge LLP, Boston, Massachusetts. See "The
Merger -- Material Federal Income Tax Consequences" on p. 35.


                                    EXPERTS


     Ernst & Young LLP, independent auditors, have audited Affymetrix's
financial statements and schedule included in its Annual Report on Form 10-K for
the year ended December 31, 1998, as set forth in their report, which is
incorporated by reference in this document. Our financial statements and
schedule are incorporated by reference in reliance on Ernst & Young LLP's
report, given on their authority as experts in accounting and auditing.


     Ernst & Young LLP, independent auditors, have audited Genetic Microsystems'
financial statements for the year ended December 31, 1998 and for the period
from August 7, 1997 (date of inception) to December 31, 1997, as set forth in
their report. We have included these financial statements in this document in
reliance on Ernst & Young LLP's report, given on their authority as experts in
accounting and auditing.

                      WHERE YOU CAN FIND MORE INFORMATION

     Affymetrix is subject to the informational requirements of the Exchange Act
and, in accordance therewith, file reports, proxy statements and other
information with the Securities and Exchange Commission. The reports, proxy
statements and other information filed by Affymetrix with the Securities and
Exchange Commission can be inspected and copied at the public reference
facilities maintained by the Securities and Exchange Commission at Room 1024,
450 Fifth Street, N.W., Washington, D.C. 20549, and at the Securities and
Exchange Commission Regional Offices located at 7 World Trade Center, 13th
floor, New York, New York 10048 and 500 West Madison Street, Suite 1400,
Chicago, Illinois 60661. Copies of such material also can be obtained at
prescribed rates from the Public Reference Section of the Securities and
Exchange Commission at 450 Fifth Street, Washington, D.C. 20549. Information
regarding the Public Reference Room may be obtained by calling the Securities
and Exchange Commission at (800) 732-0330. In addition, Affymetrix is required
to file electronic versions of such material with the Securities and Exchange
Commission through the Securities and Exchange Commission's Electronic Data
Gathering, Analysis and Retrieval (EDGAR) system. The Securities and Exchange
Commission maintains a World Wide Web site at http://www.sec.gov that contains
reports, proxy and information statements and other information regarding
registrants that file electronically with the Securities and Exchange
Commission. Affymetrix common stock is listed on the NASDAQ National Market and
reports and other information concerning Affymetrix can also be inspected at the
offices of the National Association of Securities Dealers, Inc. at 1735 K
Street, N.W., Washington, D.C. 20001-1500.

     Affymetrix has filed with the Securities and Exchange Commission a
Registration Statement on Form S-4 under the Exchange Act with respect to the
shares of Affymetrix common stock to be issued pursuant to the merger agreement.

     The Securities and Exchange Commission allows Affymetrix to "incorporate by
reference" information into this document, which means that Affymetrix can
disclose important information to you by referring you to another document filed
separately with the Securities and Exchange Commission. Statements contained in
this document or in any document incorporated by reference in this document as
to the contents of any contract or other document referred to herein or therein
are

                                       81
<PAGE>   89

not necessarily complete, and in each instance reference is made to the copy of
such contract or other document filed as an exhibit to the Registration
Statement on Form S-4 or such other document, each such statement being
qualified in all respects by such reference. The information incorporated by
reference is deemed to be part of this document. This document incorporates by
reference the documents set forth below that Affymetrix have previously filed
with the Securities and Exchange Commission. These documents contain important
information about Affymetrix and its finances.


<TABLE>
<CAPTION>
          AFFYMETRIX SEC FILINGS
            (FILE NO. 0-28218)                           PERIOD OR DATE FILED
          ----------------------                         --------------------
<S>                                           <C>
Annual Report on Form 10-K                    Year ended December 31, 1998
Quarterly Reports on Form 10-Q                Quarters ended March 31, 1999, June 30,
                                              1999 and September 30, 1999
1999 Proxy Statement                          For annual meeting of stockholders held on
                                              June 9, 1999
Current Reports on Form 8-K                   Filed on April 1, 1999 and September 28,
                                              1999
Description of rights to purchase Series B    Filed on October 16, 1999
  Junior Participating Preferred Stock
  from Registration Statement on Form 8-A
</TABLE>


     We are also incorporating by reference additional documents that we filed
with the Securities and Exchange Commission between the date of this document
and the date of the special meeting.

     Affymetrix has supplied all information contained or incorporated by
reference in this document relating to Affymetrix and Genetic MicroSystems has
supplied all such information relating to Genetic MicroSystems.

     Documents incorporated by reference are available from Affymetrix without
charge, excluding all exhibits unless Affymetrix has specifically incorporated
by reference an exhibit in this document. Stockholders may obtain documents
incorporated by reference in this document by requesting them in writing or by
telephone from the appropriate party at the following addresses:


                                AFFYMETRIX, INC.

                              CORPORATE SECRETARY
                            3380 CENTRAL EXPRESSWAY
                         SANTA CLARA, CALIFORNIA 95051
                                 (408) 731-5000

     Genetic MicroSystems is a privately held corporation that is not subject to
the reporting requirements of the Securities Exchange Act of 1934, as amended,
and therefore does not incorporate information in this document by reference
unless such information appears in an Appendix to this document.


     YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED OR INCORPORATED BY
REFERENCE IN THIS DOCUMENT TO VOTE ON THE MERGER AGREEMENT. AFFYMETRIX AND
GENETIC MICROSYSTEMS HAVE NOT AUTHORIZED ANYONE TO PROVIDE YOU WITH INFORMATION
THAT IS DIFFERENT FROM WHAT IS CONTAINED IN THIS DOCUMENT. THIS DOCUMENT IS
DATED --, 1999. YOU SHOULD NOT ASSUME THAT THE INFORMATION CONTAINED IN THIS
DOCUMENT IS ACCURATE AS OF ANY DATE OTHER THAN SUCH DATE, AND NEITHER THE
MAILING OF THIS DOCUMENT TO STOCKHOLDERS OF GENETIC MICROSYSTEMS NOR THE
ISSUANCE OF AFFYMETRIX COMMON STOCK IN THE MERGER SHALL CREATE ANY IMPLICATION
TO THE CONTRARY.


                                       82
<PAGE>   90

                                                                      APPENDIX A
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

                          AGREEMENT AND PLAN OF MERGER
                                     AMONG
                               AFFYMETRIX, INC.,
                             GMS ACQUISITION, INC.,
                          GENETIC MICROSYSTEMS, INC.,
                                  JEAN MONTAGU
                        (AS STOCKHOLDER REPRESENTATIVE)

                                      AND
               THE STOCKHOLDERS SET FORTH ON THE SIGNATURE PAGES
                               TO THIS AGREEMENT

                         DATED AS OF SEPTEMBER 10, 1999

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                                       A-1
<PAGE>   91

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<C>     <S>  <C>                                                           <C>
                                   RECITALS
                                   ARTICLE I
                                  DEFINITIONS

                                  ARTICLE II
                      THE MERGER; CLOSING; EFFECTIVE TIME
  2.1.  The Merger.......................................................  A-11
  2.2.  Closing..........................................................  A-11
  2.3.  Effective Time...................................................  A-11

                                  ARTICLE III
                     ARTICLES OF ORGANIZATION AND BY-LAWS
                         OF THE SURVIVING CORPORATION

  3.1.  The Articles of Organization.....................................  A-11
  3.2.  The By-Laws......................................................  A-11

                                  ARTICLE IV
                            OFFICERS AND DIRECTORS
                         OF THE SURVIVING CORPORATION

  4.1.  Directors........................................................  A-12
  4.2.  Officers.........................................................  A-12

                                   ARTICLE V
                    EFFECT OF THE MERGER ON CAPITAL STOCK;
                           EXCHANGE OF CERTIFICATES

  5.1.  Effect on Capital Stock..........................................  A-12
        (a)  Merger Consideration........................................  A-12
        (b)  Cancellation of Shares......................................  A-12
  5.2.  Exchange of Certificates for Shares..............................  A-12
        (a)  Exchange Agent..............................................  A-12
        (b)  Exchange Procedures.........................................  A-13
        (c)  Distributions with Respect to Unexchanged Shares............  A-13
        (d)  Transfers...................................................  A-14
        (e)  Fractional Shares...........................................  A-14
        (f)  Termination of Exchange Fund................................  A-14
        (g)  Lost, Stolen or Destroyed Certificates......................  A-14
        (h)  Affiliates..................................................  A-14
  5.3.  Appraisal Rights.................................................  A-14
  5.4.  Adjustments to Prevent Dilution..................................  A-15
  5.5.  Treatment of Warrants and Company Options........................  A-15
  5.6.  Appointment of Stockholder Representative........................  A-15
</TABLE>

                                       A-2
<PAGE>   92

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<C>     <S>  <C>                                                           <C>
                                  ARTICLE VI
                        REPRESENTATIONS AND WARRANTIES

  6.1.  Representations and Warranties of the Company....................  A-15
        (a)  Organization, Good Standing and Qualification...............  A-15
        (b)  Capital Structure...........................................  A-16
        (c)  Corporate Authority; Approval and Fairness..................  A-16
        (d)  Governmental Filings; No Violations.........................  A-16
        (e)  Financial Statements........................................  A-17
        (f)  Absence of Certain Changes..................................  A-17
        (g)  Litigation and Liabilities..................................  A-17
        (h)  Employee Benefits...........................................  A-18
        (i)  Compliance; Permits.........................................  A-19
        (j)  Takeover Statutes...........................................  A-19
        (k)  Environmental Matters.......................................  A-19
        (l)  Accounting and Tax Matters..................................  A-20
        (m)  Taxes.......................................................  A-20
        (n)  Labor Matters...............................................  A-20
        (o)  Insurance...................................................  A-21
        (p)  Intellectual Property.......................................  A-21
        (q)  Year 2000 Compliance........................................  A-23
        (r)  Title to Properties; Encumbrances...........................  A-23
        (s)  Contracts...................................................  A-23
        (t)  Condition and Sufficiency of Assets.........................  A-24
        (u)  Certain Payments............................................  A-24
        (v)  Disclosure..................................................  A-24
        (w)  Books and Records...........................................  A-24
        (x)  Brokers and Finders.........................................  A-25
  6.2.  Representations and Warranties of Parent and Merger Sub..........  A-25
        (a)  Capitalization of Parent and Merger Sub.....................  A-25
        (b)  Organization, Good Standing and Qualification...............  A-25
        (c)  Corporate Authority.........................................  A-25
        (d)  Governmental Filings; No Violations.........................  A-26
        (e)  Parent Reports; Financial Statements........................  A-26
        (f)  Accounting and Tax Matters..................................  A-26
        (g)  No Parent Material Adverse Effect...........................  A-27
        (h)  Brokers and Finders.........................................  A-27

                                  ARTICLE VII
                                   COVENANTS

  7.1.  Interim Operations of the Company................................  A-27
  7.2.  Acquisition Proposals............................................  S-28
  7.3.  Information Supplied.............................................  A-29
  7.4.  Stockholders Meeting.............................................  A-29
  7.5.  Filings; Other Actions...........................................  A-29
  7.6.  Taxation and Accounting..........................................  A-31
  7.7.  Access...........................................................  A-31
  7.8.  Affiliates.......................................................  A-31
</TABLE>

                                       A-3
<PAGE>   93

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<C>     <S>  <C>                                                           <C>
  7.9.  Quotation of Parent Common Stock.................................  A-32
  7.10. Publicity........................................................  A-32
  7.11. Benefits.........................................................  A-32
        (a)  Stock Options...............................................  A-32
        (b)  Employee Benefits...........................................  A-32
  7.12. Expenses; Cash Paid to Dissenting Stockholders...................  A-33
  7.13. Takeover Statutes................................................  A-33
  7.14. Warrants.........................................................  A-33
  7.15. Assignment of Contracts..........................................  A-33

                                 ARTICLE VIII
                                  CONDITIONS

  8.1.  Conditions to Each Party's Obligation to Effect the Merger.......  A-33
        (a)  Stockholder Approval........................................  A-33
        (b)  NASDAQ Quotation............................................  A-33
        (c)  Regulatory Consents.........................................  A-33
        (d)  Litigation..................................................  A-34
        (e)  Accountant Letter...........................................  A-34
        (f)  S-4 Registration Statement..................................  A-34
        (g)  Tax Opinions................................................  A-34
  8.2.  Conditions to Obligations of Parent and Merger Sub...............  A-34
        (a)  Representations and Warranties..............................  A-34
        (b)  Performance of Obligations of the Company...................  A-34
        (c)  Consents Under Agreements...................................  A-34
        (d)  Legal Opinion...............................................  A-35
        (e)  Resignations................................................  A-35
        (f)  Non-competition Agreements..................................  A-35
        (g)  Affiliates Letters..........................................  A-35
  8.3.  Conditions to Obligation of the Company..........................  A-35
        (a)  Representations and Warranties..............................  A-35
        (b)  Performance of Obligations of Parent and Merger Sub.........  A-35
        (c)  Consents Under Agreements...................................  A-35
        (d)  Legal Opinion...............................................  A-35

                                  ARTICLE IX
                                  TERMINATION

  9.1.  Termination by Mutual Consent....................................  A-35
  9.2.  Termination by Either Parent or the Company......................  A-35
  9.3.  Termination by the Company.......................................  A-36
  9.4.  Termination by Parent............................................  A-36
  9.5.  Effect of Termination and Abandonment............................  A-36
</TABLE>

                                       A-4
<PAGE>   94

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<C>     <S>  <C>                                                           <C>
                                   ARTICLE X
                                INDEMNIFICATION

 10.1.  Survival; Right to Indemnification Not Affected by Knowledge;
        Representations and Warranties Made as of the Closing Date.......  A-37
 10.2.  Indemnification and Payment of Damages by Holders of Shares......  A-38
 10.3.  Indemnification and Payment of Damages by Parent.................  A-38
 10.4.  Limitations on Amount -- Holder of Shares........................  A-38
 10.5.  Limitations on Amount -- Parent..................................  A-38
 10.6.  Payments to Parent...............................................  A-39
 10.7.  Procedures for Indemnification...................................  A-39
 10.8.  Non-Exclusive Remedy.............................................  A-39
 10.9.  Tax Treatment....................................................  A-40
 10.10. Pooling..........................................................  A-40

                                  ARTICLE XI
                           MISCELLANEOUS AND GENERAL

 11.1.  Modification or Amendment........................................  A-40
 11.2.  Waiver of Conditions.............................................  A-40
 11.3.  Counterparts.....................................................  A-40
 11.4.  GOVERNING LAW AND VENUE; WAIVER OF JURY TRIAL....................  A-40
 11.5.  Notices..........................................................  A-41
 11.6.  Entire Agreement.................................................  A-42
 11.7.  No Third Party Beneficiaries.....................................  A-42
 11.8.  Obligations of Parent............................................  A-42
 11.9.  Transfer Taxes...................................................  A-42
 11.10. Severability.....................................................  A-42
 11.11. Interpretation...................................................  A-42
 11.12. Assignment.......................................................  A-42
 11.13. Specific Performance.............................................  A-43
</TABLE>

                                       A-5
<PAGE>   95

                          AGREEMENT AND PLAN OF MERGER

     This AGREEMENT AND PLAN OF MERGER (hereinafter called this "Agreement") is
made as of September 10, 1999, by and among Genetic MicroSystems, Inc., a
Massachusetts corporation (the "Company"), Affymetrix, Inc., a Delaware
corporation ("Parent"), GMS Acquisition, Inc., a Massachusetts corporation and a
wholly-owned subsidiary of Parent ("Merger Sub," the Company and Merger Sub
sometimes being hereinafter collectively referred to as the "Constituent
Corporations") and Jean Montagu (the "Stockholder Representative") and the
stockholders of the Company set forth on the signature pages to this Agreement.

                                    RECITALS

     WHEREAS, the respective boards of directors of each of Parent, Merger Sub
and the Company have approved the merger of the Company with and into Merger Sub
(the "Merger") and approved the Merger upon the terms and subject to the
conditions set forth in this Agreement and have determined that the Merger and
the other transactions contemplated by this Agreement are fair to, and in the
best interests of, their respective stockholders;

     WHEREAS, it is intended that, for federal income tax purposes, the Merger
shall qualify as a reorganization under the provisions of Section 368(a) of the
Internal Revenue Code of 1986, as amended, and the rules and regulations
promulgated thereunder (the "Code") and the parties intend, by executing this
Agreement, to adopt this Agreement as a plan of reorganization within the
meaning of Section 368 of the Code;

     WHEREAS, for financial accounting purposes, it is intended that the Merger
shall be accounted for as a "pooling-of-interests;"

     WHEREAS, contemporaneously with the execution and delivery of this
Agreement, as a condition and inducement to Parent's and Merger Sub's
willingness to enter into this Agreement, the Company is entering into a stock
option agreement with Parent (the "Stock Option Agreement"), pursuant to which
the Company has granted to Parent an option to purchase Common Shares (as
defined below) under the terms and conditions set forth in the Stock Option
Agreement;

     WHEREAS, concurrently with the execution and delivery of this Agreement and
as a condition and inducement to Parent's and Merger Sub's willingness to enter
into this Agreement, certain stockholders of the Company have entered into
Stockholder Voting Agreements, dated as of the date of this Agreement
(collectively, the "Stockholder Voting Agreements"), pursuant to which such
stockholders have agreed to, among other things, vote their shares of capital
stock of the Company in favor of this Agreement and the Merger; and

     WHEREAS, the Company, Parent and Merger Sub desire to make certain
representations, warranties, covenants and agreements in connection with this
Agreement.

                                       A-6
<PAGE>   96

     NOW, THEREFORE, in consideration of the premises, and of the
representations, warranties, covenants and agreements contained herein, the
parties hereto agree as follows:

                                   ARTICLE I

                                  DEFINITIONS

     For purposes of this Agreement, the following terms have the meanings
specified or referred to in this Article I:

     "Acquisition Proposal" shall have the meaning set forth in Section 7.2.

     "Affiliate" means with respect to any Person, any director or executive
officer of such Person and any other Person which would constitute an
"affiliate" of such Person within the meaning of Rule 12b-2 under the Exchange
Act.

     "Affiliates Letter" shall have the meaning set forth in Section 7.8.

     "Agreement" shall have the meaning set forth in the paragraph before the
Recitals.

     "Appraisal Rights Provisions" shall have the meaning set forth in Section
5.1(a).

     "Balance Sheet Date" shall have the meaning set forth in Section 6.1(e).

     "Bankruptcy and Equity Exception" shall have the meaning set forth in
Section 6.1(c).

     "By-laws" shall have the meaning set forth in Section 3.2.

     "Certificate" shall have the meaning set forth in Section 5.1(a).

     "Charter" shall have the meaning set forth in Section 3.1.

     "Closing" shall have the meaning set forth in Section 2.2.

     "Closing Date" shall have the meaning set forth in Section 2.2.

     "Code" shall have the meaning set forth in the Recitals.

     "Commercial Software Licenses" shall have the meaning set forth in Section
6.1(p).

     "Company" shall have the meaning set forth in the paragraph before the
Recitals.

     "Company Disclosure Schedule" means the disclosure schedule delivered by
the Company to Parent prior to the execution and delivery of this Agreement.

     "Company Intellectual Property Rights" shall have the meaning set forth in
Section 6.1(p).

     "Company Material Adverse Effect" shall mean any change, event or effect
that, individually or in the aggregate, is or is reasonably likely to have a
material adverse effect on the financial condition, properties, prospects,
business or results of operations of the Company or on the Company's ability to
perform its obligations, if any, as contemplated in the Transaction Agreements.

     "Company Option" shall have the meaning set forth in Section 6.1(b).

     "Company Requisite Vote" shall have the meaning set forth in Section
6.1(c).

     "Compensation and Benefit Plans" shall have the meaning set forth in
Section 6.1(h).

     "Common Share" shall have the meaning set forth in Section 5.1(a).

     "Constituent Corporations" shall have the meaning set forth in the
paragraph before the Recitals.

                                       A-7
<PAGE>   97

     "Contract" means any agreement, lease, contract, note, mortgage, indenture,
arrangement or other obligation.

     "Damages" shall have the meaning set forth in Section 10.2.

     "Dissenting Shares" shall have the meaning set forth in Section 5.1(a).

     "Dissenting Stockholders" shall have the meaning set forth in Section
5.1(a).

     "Effective Time" shall have the meaning set forth in Section 2.3.

     "Encumbrance" means any mortgage, easement, right of way, charge, claim,
community property interest, condition, equitable interest, lien, option,
pledge, security interest, right of first refusal, or restriction or adverse
claim of any kind, including any restriction on use, voting, transfer, receipt
of income, or exercise of any other attribute of ownership, or any other
encumbrance or exception to title of any kind.

     "Environmental Health and Safety Law" means any federal, state, local or
foreign statute, law, regulation, order, decree, permit, authorization, common
law or binding agency requirement relating to: (A) the protection, investigation
or restoration of the environment, health, safety, or natural resources, (B) the
handling, use, presence, disposal, release or threatened release of any
Hazardous Substance or (C) noise, odor, indoor air, employee exposure, wetlands,
pollution, contamination or any injury or threat of injury to persons or
property.

     "ERISA" shall have the meaning set forth in Section 6.1(h).

     "ERISA Affiliate" shall have the meaning set forth in Section 6.1(h).

     "Escrow Agreement" means the Escrow Agreement dated as of the date of this
Agreement among Parent, the Stockholder Representative and the Escrow Agent (as
defined in the Escrow Agreement).

     "Excluded Shares" shall have the meaning set forth in Section 5.1(a).

     "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended.

     "Exchange Agent" shall have the meaning set forth in Section 5.2(a).

     "Exchange Fund" shall have the meaning set forth in Section 5.2(a).

     "Financial Statements" shall have the meaning set forth in Section 6.1(e).

     "GAAP" means United States generally accepted accounting principles.

     "Governmental Entity" means any (i) nation, state, county, city, town,
village, district, or other jurisdiction of any nature, (ii) federal, state,
local, municipal, foreign, or other government; (iii) governmental or
quasi-governmental authority of any nature (including any governmental agency,
branch, department, official, or entity and any court or other tribunal) or (iv)
body exercising, or entitled to exercise, any administrative, executive,
judicial, legislative, police, regulatory, or taxing authority or power of any
nature (including any self-regulatory organization).

     "Hazardous Substance" means any substance that is: (A) listed, classified
or regulated pursuant to any Environmental Health and Safety Law; (B) any
petroleum product or by-product, asbestos-containing material, lead-containing
paint, polychlorinated biphenyls, radioactive material or radon; or (C) any
other substance which may be the subject of regulatory action by any Government
Entity in connection with any Environmental Health and Safety Law.

     "Holdback" means 10% (or the maximum percentage permitted that is
consistent with pooling of interests accounting treatment) of the aggregate
number of shares of Parent Common Stock to be delivered by Parent at Closing,
rounded down to the nearest whole share.

                                       A-8
<PAGE>   98

     "Holdback Account" means the account maintained by the Escrow Agent
pursuant to the terms of the Escrow Agreement in respect of the Holdback.

     "HSR Act" shall mean the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended.

     "Indemnified Party" shall have the meaning set forth in Section 10.7.

     "Indemnifying Parties" shall have the meaning set forth in Section 10.7.

     "Intellectual Property Rights" shall have the meaning set forth in Section
6.1(p).

     "knowledge" with respect to the Company shall mean the actual knowledge of
Jean Montagu, Stanley Rose, Peter Honkanen or Peter Lewis or to the knowledge
that such individuals would reasonably be expected to have after reasonable
inquiry arising after the conduct by such individuals of a reasonable
investigation with respect to the facts or matters specified.

     "Law" means any federal, state, local, foreign or international law,
statute, ordinance, rule, regulation, treaty, judgment, order, injunction,
decree, arbitration award, agency requirement, license or permit of any
Governmental Entity.

     "Massachusetts Articles of Merger" shall have the meaning set forth in
Section 2.3.

     "MBCL" shall have the meaning set forth in Section 2.1.

     "Merger" shall have the meaning set forth in the Recitals.

     "Merger Consideration" shall have the meaning set forth in Section 5.1(a).

     "Merger Sub" shall have the meaning set forth in the paragraph before the
Recitals.

     "NASDAQ" shall mean the NASDAQ Stock Market.

     "New Parent Option" shall have the meaning set forth in Section 7.11(a).

     "Order" shall have the meaning set forth in Section 8.1(d).

     "Organizational Documents" shall have the meaning set forth in Section
6.1(a).

     "Parent" shall have the meaning set forth in the paragraph before the
Recitals.

     "Parent Common Stock" shall have the meaning set forth in Section 5.1(a).

     "Parent Companies" shall have the meaning set forth in Section 5.1(a).

     "Parent Disclosure Schedule" means the disclosure schedule delivered by
Parent to the Company prior to the execution and delivery of this Agreement.

     "Parent Indemnified Parties" shall have the meaning set forth in Section
10.2.

     "Parent Material Adverse Effect" shall mean any change, event or effect
that, individually or in the aggregate, is or is reasonably likely to have a
material adverse effect on the financial condition, properties, prospects,
business or results of operations of Parent and its Subsidiaries, taken as a
whole, or on Parent's ability to perform its obligations, if any, as
contemplated in the Transaction Agreements.

     "Parent Reports" shall have the meaning set forth in Section 6.2(e).

     "Person" shall mean any individual, corporation (including not-for-profit),
general or limited partnership, limited liability company, joint venture,
estate, trust, association, organization, Governmental Entity or other entity of
any kind or nature.

     "Pooling Affiliates Letter" shall have the meaning set forth in Section
7.8.

                                       A-9
<PAGE>   99

     "Preferred Share" shall have the meaning set forth in Section 5.1(a).

     "Prospectus/Proxy Statement" shall have the meaning set forth in Section
7.3.

     "Representatives" shall have the meaning set forth in Section 7.7.

     "S-4 Registration Statement" shall have the meaning set forth in Section
7.3.

     "SEC" shall mean the Securities and Exchange Commission.

     "Securities Act" means the Securities Act of 1933, as amended.

     "Shares" shall have the meaning set forth in Section 5.1(a).

     "Stock Option Agreement" shall have the meaning set forth in the Recitals.

     "Stockholder Representative" shall have the meaning set forth in the
paragraph before the Recitals.

     "Stockholder Voting Agreements" shall have the meaning set forth in the
Recitals.

     "Stockholders Meeting" shall have the meaning set forth in Section 7.4.

     "Subsidiary" shall mean, with respect to the Company, Parent or Merger Sub,
as the case may be, any entity, whether incorporated or unincorporated, of which
at least a majority of the securities or ownership interests having by their
terms ordinary voting power to elect a majority of the board of directors or
other persons performing similar functions is directly or indirectly owned or
controlled by such party or by one or more of its respective Subsidiaries or by
such party and any one or more of its respective Subsidiaries.

     "Superior Proposal" shall have the meaning set forth in Section 7.2.

     "Survival Date" shall have the meaning set forth in Section 10.1.

     "Surviving Corporation" shall have the meaning set forth in Section 2.1.

     "Systems" shall have the meaning set forth in Section 6.1(q).

     "Takeover Statute" shall have the meaning set forth in Section 6.1(j).

     "Tax" (including, with correlative meaning, the terms "Taxes", and
"Taxable") means all federal, state, local and foreign income, profits,
franchise, gross receipts, environmental, customs duty, capital stock,
severances, stamp, payroll, sales, employment, unemployment, disability, use,
property, withholding, excise, production, value added, occupancy and other
taxes, duties or assessments of any nature whatsoever, together with all
interest, penalties and additions imposed with respect to such amounts and any
interest in respect of such penalties and additions.

     "Tax Return" means all returns and reports (including elections,
declarations, disclosures, schedules, estimates and information returns)
required to be supplied to a Tax authority relating to Taxes.

     "Termination Date" shall have the meaning set forth in Section 9.2.

     "Third Party Intellectual Property Licenses" shall have the meaning set
forth in Section 6.1(p).

     "Transaction Agreements" shall mean the Merger Agreement, the Stock Option
Agreement, the Stockholder Voting Agreements and the Escrow Agreement.

     "Voting Debt" shall have the meaning set forth in Section 6.1(b).

     "Warrant" shall have the meaning set forth in Section 6.1(b).

                                      A-10
<PAGE>   100

     "Year 2000 Compliant" means that a System shall be able to process
(including without limitation calculate, compare and sequence) accurately date
and time from, into and between the years 1999 and 2000 and any other years in
the 20th and 21st centuries, including the making of accurate leap year
calculations.

                                   ARTICLE II

                      THE MERGER; CLOSING; EFFECTIVE TIME

     2.1.  The Merger.  Upon the terms and subject to the conditions set forth
in this Agreement, at the Effective Time, the Company shall be merged with and
into Merger Sub and the separate corporate existence of the Company shall
thereupon cease. Merger Sub shall be the surviving corporation in the Merger
(sometimes hereinafter referred to as the "Surviving Corporation"). The Merger
shall have the effects specified in the Massachusetts Business Corporation Law,
as amended (the "MBCL").

     2.2.  Closing.  The closing of the Merger (the "Closing") shall take place
(i) at the offices of Sullivan & Cromwell, 125 Broad Street, New York, New York
at 9:00 A.M. on the later of (x) January 14, 2000 or such earlier date as
selected by Parent in a written notice delivered to the Company or (y) the first
business day on which the last to be fulfilled or waived of the conditions set
forth in Article VIII (other than those conditions that by their nature are to
be satisfied at the Closing, but subject to the fulfillment or waiver of those
conditions) shall be satisfied or waived in accordance with this Agreement or
(ii) at such other place and time and/or on such other date as the Company and
Parent may agree in writing (the "Closing Date").

     2.3.  Effective Time.  As soon as practicable following the Closing, the
Company and Parent will cause Articles of Merger (the "Massachusetts Articles of
Merger") to be executed, acknowledged and filed with the Secretary of State of
the Commonwealth of Massachusetts as provided in Section 84 of Chapter 156B of
the MBCL. The Merger shall become effective at the time when the Massachusetts
Articles of Merger have been duly filed with the Secretary of State of the
Commonwealth of Massachusetts, unless such Massachusetts Articles of Merger
specify a later effective date in which event the Merger shall become effective
on such later date (the "Effective Time").

                                  ARTICLE III

                      ARTICLES OF ORGANIZATION AND BY-LAWS
                          OF THE SURVIVING CORPORATION

     3.1.  The Articles of Organization.  The articles of organization of Merger
Sub as in effect immediately prior to the Effective Time shall be the articles
of organization of the Surviving Corporation (the "Charter"), until duly amended
as provided therein or by applicable law, except that Article 1 of the Charter
shall be amended to change the name of the Surviving Corporation to "Genetic
MicroSystems, Inc."

     3.2.  The By-Laws.  The by-laws of Merger Sub in effect at the Effective
Time shall be the by-laws of the Surviving Corporation (the "By-Laws"), until
thereafter amended as provided therein or by applicable law.

                                      A-11
<PAGE>   101

                                   ARTICLE IV

                             OFFICERS AND DIRECTORS
                          OF THE SURVIVING CORPORATION

     4.1.  Directors.  The directors of Merger Sub at the Effective Time shall,
from and after the Effective Time, be the directors of the Surviving Corporation
until their successors have been duly elected or appointed and qualified or
until their earlier death, resignation or removal in accordance with the Charter
and the By-Laws. Prior to the Effective Time, the Company shall take all actions
necessary to obtain any resignations of its directors necessary to give effect
to the provisions of this Section.

     4.2.  Officers.  The officers of Merger Sub at the Effective Time shall,
from and after the Effective Time, be the officers of the Surviving Corporation
until their successors have been duly elected or appointed and qualified or
until their earlier death, resignation or removal in accordance with the Charter
and the By-Laws.

                                   ARTICLE V

                     EFFECT OF THE MERGER ON CAPITAL STOCK;
                            EXCHANGE OF CERTIFICATES

     5.1.  Effect on Capital Stock.  At the Effective Time, as a result of the
Merger and without any action on the part of the holder of any capital stock of
the Company:

     (a) Merger Consideration.  Each share of the Common Stock, no par value per
share, of the Company and each share of the Preferred Stock, par value $0.01 per
share, of the Company (as applicable a "Common Share" or a "Preferred Share"; or
collectively, the "Shares") issued and outstanding immediately prior to the
Effective Time (other than Shares ("Dissenting Shares") that are owned by
stockholders exercising appraisal rights ("Dissenting Stockholders") pursuant to
Chapter 156B Sections 86 through 98 of the MBCL (the "Appraisal Rights
Provisions") or Shares owned by Parent, Merger Sub or any other direct or
indirect Subsidiary of Parent (collectively, the "Parent Companies") or Shares
that are owned by the Company and are not held on behalf of third parties
(collectively, "Excluded Shares")) shall, subject to Section 5.2(e), be
converted into the right to receive that number of shares (the "Merger
Consideration"), of Common Stock, par value $0.01 per share, of Parent ("Parent
Common Stock") determined by dividing 1,070,000 by the aggregate number of
Shares issued and outstanding and Shares subject to Company Options or Warrants
(whether vested or unvested or currently exercisable or unexercisable), in each
case, immediately prior to the Effective Time. At the Effective Time, all Shares
shall no longer be outstanding and shall be canceled and retired and shall cease
to exist, and each certificate (a "Certificate") formerly representing any of
such Shares (other than Excluded Shares) shall thereafter represent only the
right to the Merger Consideration and the right, if any, to receive pursuant to
Section 5.2(e) cash in lieu of fractional shares into which such Shares have
been converted pursuant to this Section 5.1(a) and any distribution or dividend
pursuant to Section 5.2(c).

     (b) Cancellation of Shares.  Each Share issued and outstanding immediately
prior to the Effective Time and owned by any of the Parent Companies or owned by
the Company (other than Shares that are in each case owned on behalf of third
parties), shall, by virtue of the Merger and without any action on the part of
the holder thereof, cease to be outstanding, shall be canceled and retired
without payment of any consideration therefor and shall cease to exist.

     5.2.  Exchange of Certificates for Shares.

     (a) Exchange Agent.  As of the Effective Time, Parent shall deposit, or
shall cause to be deposited, with an exchange agent selected by Parent (the
"Exchange Agent"), for the benefit of the

                                      A-12
<PAGE>   102

holders of Shares, certificates representing the shares of Parent Common Stock
and, after the Effective Time, if applicable, any cash, dividends or other
distributions with respect to the Parent Common Stock to be issued or paid
pursuant to the last sentence of Section 5.1(a) in exchange for Shares
outstanding immediately prior to the Effective time upon due surrender of the
Certificates (or affidavits of loss in lieu thereof) pursuant to the provisions
of this Article V (such certificates for shares of Parent Common Stock, together
with the amount of any dividends or other distributions payable with respect
thereto, being hereinafter referred to as the "Exchange Fund").

     (b) Exchange Procedures.  Promptly after the Effective Time, the Surviving
Corporation shall cause the Exchange Agent to mail to each holder of record of
Shares (other than holders of Excluded Shares) (i) a letter of transmittal
specifying that delivery shall be effected, and risk of loss and title to the
Certificates shall pass, only upon delivery of the Certificates (or affidavits
of loss in lieu thereof) to the Exchange Agent and (ii) instructions for use in
effecting the surrender of the Certificates in exchange for (A) certificates
representing shares of Parent Common Stock and (B) any unpaid dividends and
other distributions and cash in lieu of fractional shares. Subject to Section
5.2(h), upon surrender of a Certificate for cancellation to the Exchange Agent
together with such letter of transmittal, duly executed, the holder of such
Certificate shall be entitled to receive in exchange therefor (x) a certificate
representing that number of whole shares of Parent Common Stock that such holder
is entitled to receive pursuant to this Article V, (y) a check in the amount
(after giving effect to any required tax withholdings) of (A) any cash in lieu
of fractional shares plus (B) any unpaid non-stock dividends and any other
dividends or other distributions that such holder has the right to receive
pursuant to the provisions of this Article V, and the Certificate so surrendered
shall forthwith be cancelled. No interest will be paid or accrued on any amount
payable upon due surrender of the Certificates. In the event of a transfer of
ownership of Shares that is not registered in the transfer records of the
Company, a certificate representing the proper number of shares of Parent Common
Stock, together with a check for any cash to be paid upon due surrender of the
Certificate and any other dividends or distributions in respect thereof, may be
issued and/or paid to such a transferee if the Certificate formerly representing
such Shares is presented to the Exchange Agent, accompanied by all documents
required to evidence and effect such transfer and to evidence that any
applicable stock transfer taxes have been paid. If any certificate for shares of
Parent Common Stock is to be issued in a name other than that in which the
Certificate surrendered in exchange therefor is registered, it shall be a
condition of such exchange that the Person requesting such exchange shall pay
any transfer or other taxes required by reason of the issuance of certificates
for shares of Parent Common Stock in a name other than that of the registered
holder of the Certificate surrendered, or shall establish to the satisfaction of
Parent or the Exchange Agent that such tax has been paid or is not applicable.

     (c) Distributions with Respect to Unexchanged Shares.  All shares of Parent
Common Stock to be issued pursuant to the Merger shall be deemed issued and
outstanding as of the Effective Time and whenever a dividend or other
distribution is declared by Parent in respect of the Parent Common Stock, the
record date for which is at or after the Effective Time, that declaration shall
include dividends or other distributions in respect of all shares issuable
pursuant to this Agreement. No dividends or other distributions in respect of
the Parent Common Stock shall be paid to any holder of any unsurrendered
Certificate until such Certificate is surrendered for exchange in accordance
with this Article V. Subject to the effect of applicable laws, following
surrender of any such Certificate, there shall be issued and/or paid to the
holder of the certificates representing whole shares of Parent Common Stock
issued in exchange therefor, without interest, (A) at the time of such
surrender, the dividends or other distributions with a record date for which is
at or after the Effective Time theretofore payable with respect to such whole
shares of Parent Common Stock and not paid and (B) at the appropriate payment
date, the dividends or other distributions payable with respect to such

                                      A-13
<PAGE>   103

whole shares of Parent Common Stock with a record date for which is at or after
the Effective Time but with a payment date subsequent to surrender.

     (d) Transfers.  After the Effective Time, there shall be no transfers on
the stock transfer books of the Company of the Shares that were outstanding
immediately prior to the Effective Time.

     (e) Fractional Shares.  Notwithstanding any other provision of this
Agreement, no fractional shares of Parent Common Stock shall be issued and any
holder of Shares entitled to receive a fractional share of Parent Common Stock
but for this Section 5.2(e) shall be entitled to receive, as of the date on
which those holders entitled to receive fractional shares are determined, a cash
payment in lieu thereof, without interest, which payment shall represent such
holder's proportionate interest in the net proceeds from the sale by the
Exchange Agent on behalf of such holder of the aggregate fractional shares of
Parent Common Stock that such holder otherwise would be entitled to receive. Any
such sale shall be made by the Exchange Agent on the date on which those holders
entitled to receive fractional shares are determined.

     (f) Termination of Exchange Fund.  Any portion of the Exchange Fund
(including the proceeds of any investments thereof and any Parent Common Stock)
that remains unclaimed by the stockholders of the Company for 180 days after the
Effective Time shall be paid to Parent. Any stockholders of the Company who have
not theretofore complied with this Article V shall thereafter look only to
Parent for payment of their shares of Parent Common Stock and any cash,
dividends and other distributions in respect thereof payable and/or issuable
pursuant to Section 5.1 and Section 5.2(c) upon due surrender of their
Certificates (or affidavits of loss in lieu thereof), in each case, without any
interest thereon. Notwithstanding the foregoing, none of Parent, the Surviving
Corporation, the Exchange Agent or any other Person shall be liable to any
former holder of Shares for any amount properly delivered to a public official
pursuant to applicable abandoned property, escheat or similar laws.

     (g) Lost, Stolen or Destroyed Certificates.  In the event any Certificate
shall have been lost, stolen or destroyed, upon the making and delivery to the
Exchange Agent of an affidavit of that fact by the Person claiming such
Certificate to be lost, stolen or destroyed and, if required by Parent, the
posting by such Person of a bond in customary amount as indemnity against any
claim that may be made against it with respect to such Certificate, the Exchange
Agent will issue in exchange for such lost, stolen or destroyed Certificate the
shares of Parent Common Stock and any cash payable and any unpaid dividends or
other distributions in respect thereof pursuant to Section 5.2(c) upon due
surrender of and deliverable in respect of the Shares represented by such
Certificate pursuant to this Agreement.

     (h) Affiliates.  Notwithstanding anything herein to the contrary,
Certificates surrendered for exchange by any "affiliate" (as determined pursuant
to Section 7.8) of the Company shall not be exchanged until Parent has received
a written agreement from such Person as provided in Section 7.8 hereof.

     5.3.  Appraisal Rights.  No Dissenting Stockholder shall be entitled to
shares of Parent Common Stock or cash in lieu of fractional shares thereof or
any dividends or other distributions pursuant to this Article V unless and until
the holder thereof shall have failed to perfect or shall have effectively
withdrawn or lost such holder's right to dissent from the Merger under the
Appraisal Rights Provisions, and any Dissenting Stockholder shall be entitled to
receive only the payment provided by the Appraisal Rights Provisions with
respect to Shares owned by such Dissenting Stockholder. If any Person who
otherwise would be deemed a Dissenting Stockholder shall have failed to perfect
properly or shall have effectively withdrawn or lost the right to dissent with
respect to any Shares, such Shares shall thereupon be treated as though such
Shares had been converted into shares of Parent Common Stock pursuant to Section
5.1 hereof. The Company shall give Parent

                                      A-14
<PAGE>   104

(i) prompt notice of any demands for appraisal, attempted withdrawals of such
demands, and any other instruments served pursuant to applicable law received by
the Company relating to stockholders' rights of appraisal and (ii) the
opportunity to direct and conclude all negotiations and proceedings with respect
to demand for appraisal under the MBCL. The Company shall not, except with the
prior written consent of Parent, voluntarily make any payment with respect to
any demands for appraisals of Dissenting Shares, offer to settle or settle any
such demands or approve any withdrawal of any such demands; and Parent agrees to
provide the Company with all funds necessary to pay or settle such demands for
appraisal.

     5.4.  Adjustments to Prevent Dilution.  In the event that the Company
changes the number of Shares or securities convertible or exchangeable into or
exercisable for Shares, or Parent changes the number of shares of Parent Common
Stock or securities convertible or exchangeable into or exercisable for shares
of Parent Common Stock, issued and outstanding prior to the Effective Time as a
result of a reclassification, stock split (including a reverse split), stock
dividend or distribution, recapitalization, merger, subdivision, issuer tender
or exchange offer, or other similar transaction, the Merger Consideration shall
be equitably adjusted.

     5.5.  Treatment of Warrants and Company Options.  The Company Options shall
be treated as set forth in Section 7.11 and the Warrants shall be treated as set
forth in Section 7.14.

     5.6.  Appointment of Stockholder Representative.  (a) Each holder of Shares
who votes in favor of the Merger or who receives or accepts the Merger
Consideration shall be deemed to have consented in all respects to the
appointment of Jean Montagu as Stockholder Representative and shall be deemed to
have consented to the performance by the Stockholder Representative of all
rights and obligations conferred on the Stockholder Representative under this
Agreement and the Escrow Agreement.

     (b) The Stockholder Representative shall not be liable to the Stockholders
of the Company for any action taken or omitted to be taken hereunder as
Stockholder Representative, except due to gross negligence or bad faith. The
Stockholders of Genetic MicroSystems shall indemnify the Stockholder
Representative and hold the Stockholder Representative harmless against any
loss, liability or expense incurred without gross negligence or bad faith on the
part of the Stockholder Representative and arising out of or in connection with
the acceptance or administration of the Stockholder Representative's duties
hereunder, including the reasonable fees and expenses of any legal counsel
retained by the Stockholder Representative.

                                   ARTICLE VI

                         REPRESENTATIONS AND WARRANTIES

     6.1.  Representations and Warranties of the Company.  The Company, the
Stockholder Representative (on behalf of the stockholders of the Company) and
the stockholders set forth on the signature pages to this Agreement hereby
represent and warrant to Parent and Merger Sub that, except as set forth in a
correspondingly numbered schedule in the Company Disclosure Schedule:

     (a) Organization, Good Standing and Qualification.  The Company is a
corporation duly organized, validly existing and in good standing under the laws
of the Commonwealth of Massachusetts and has all requisite corporate or similar
power and authority to own and operate its properties and assets and to carry on
its business as presently conducted and is qualified to do business and is in
good standing as a foreign corporation in each jurisdiction where the ownership
or operation of its properties or conduct of its business requires such
qualification. The Company has delivered to Parent a complete and correct copy
of the Company's Restated Articles of Organization and By-laws (collectively,
"Organizational Documents"), each as amended to date. The Company's
Organizational Documents so delivered are in full force and effect. Section
6.1(a) of the Company
                                      A-15
<PAGE>   105

Disclosure Schedule contains a correct and complete list of each jurisdiction
where the Company is organized and/or qualified to do business. The Company has
no Subsidiaries and owns no security, equity or other interest in any Person.

     (b) Capital Structure.  The authorized capital stock of the Company
consists of 5,000,000 Common Shares, of which 1,006,702 Common Shares were
outstanding as of the close of business on September 8, 1999, and 2,636,353
Preferred Shares, of which 2,000,000 Series A Preferred Shares and 431,977
Series B Preferred Shares were outstanding as of the close of business on
September 8, 1999. All of the outstanding Shares have been duly authorized and
are validly issued, fully paid and nonassessable. Other than, as of the date
hereof (i) 684,297 Common Shares reserved for issuance under the Stock Option
Agreement, (ii) 346,864 Common Shares reserved for issuance under the Company's
1998 Stock Option Plan (the "Stock Plan") and (iii) 122,197 Common Shares
reserved for issuance in connection with the Warrants, the Company has no Shares
reserved for issuance. The Company Disclosure Schedule contains a correct and
complete list of each outstanding option to purchase Shares under the Stock Plan
(each a "Company Option") and each outstanding Warrant to purchase Shares (each
a "Warrant"), including the holder, date of grant, exercise price and number of
Shares subject thereto. Except as set forth above or in Schedule 6.1(b) of the
Company Disclosure Schedule, there are no preemptive or other outstanding
rights, options, warrants, conversion rights, stock appreciation rights,
redemption rights, repurchase rights, agreements, arrangements or commitments to
issue or sell any shares of capital stock or other securities of the Company or
any securities or obligations convertible or exchangeable into or exercisable
for, or giving any Person a right to subscribe for or acquire, any securities of
the Company, and no securities or obligations evidencing such rights are
authorized, issued or outstanding. The Company does not have outstanding any
bonds, debentures, notes or other obligations the holders of which have the
right to vote (or convertible into or exercisable for securities having the
right to vote) with the stockholders of the Company on any matter ("Voting
Debt").

     (c) Corporate Authority; Approval and Fairness.  (i) The Company has all
requisite corporate power and authority and has taken all corporate action
necessary in order to execute, deliver and perform its obligations under this
Agreement and the Stock Option Agreement and to consummate, subject only to (x)
approval of this Agreement by the holders of two-thirds of the Common Shares
outstanding and entitled to vote, (y) approval of this Agreement (A) by the
holders of two-thirds of the Preferred Shares outstanding and entitled to vote
and (B) by the holders of a majority of the Series A Preferred Shares
outstanding and entitled to vote and (z) the affirmative vote of a majority of
the shares of the Series A Preferred Stock of the Company that the Merger does
not constitute a liquidation, dissolution or winding up of the Company as set
forth in the Company's Organizational Documents (collectively, the "Company
Requisite Vote"). This Agreement and the Stock Option Agreement are valid and
binding agreements of the Company enforceable against the Company in accordance
with their respective terms, subject to bankruptcy, insolvency, fraudulent
transfer, reorganization, moratorium and similar laws of general applicability
relating to or affecting creditors' rights and to general equity principles (the
"Bankruptcy and Equity Exception").

     (ii) The Board of Directors of the Company has unanimously approved this
Agreement and the Stock Option Agreement and the Merger and the other
transactions contemplated hereby.

     (d) Governmental Filings; No Violations.  (i) Except for (A) the filing of
the Massachusetts Articles of Merger pursuant to Section 2.3, (B) filings and/or
notices under the HSR Act and (C) such consents, approvals, orders and
authorizations as may be required under applicable state securities or
"blue-sky" laws, no notices, reports or other filings are required to be made by
the Company with, nor are any consents, registrations, approvals, permits or
authorizations required to be obtained by the Company from any Governmental
Entity, in connection with the execution and

                                      A-16
<PAGE>   106

delivery of this Agreement and the Stock Option Agreement by the Company and the
consummation by the Company of the Merger and the other transactions
contemplated hereby and thereby.

     (ii) The execution, delivery and performance of this Agreement and the
Stock Option Agreement by the Company do not, and the consummation by the
Company of the Merger and the other transactions contemplated hereby and thereby
will not, constitute or result in (A) a breach or violation of, or a default
under, the Organizational Documents of the Company, (B) a breach or violation
of, or a default under, the acceleration of any obligations or the creation of
any Encumbrance on the assets of the Company (with or without notice, lapse of
time or both) pursuant to, any Contracts binding upon the Company or any Law or
governmental or non-governmental permit or license to which the Company is
subject or (C) any change in the rights or obligations of any party under any of
the Contracts binding upon the Company. Schedule 6.1(d) of the Company
Disclosure Schedule sets forth a correct and complete list of Contracts of the
Company pursuant to which consents or waivers are or may be required prior to
consummation of the transactions contemplated by this Agreement and the Stock
Option Agreement.

     (e) Financial Statements.  The Company has delivered to Parent: (i) the
Company's audited balance sheets at December 31, 1997 and 1998 and the related
statements of operations and comprehensive loss, shareholders' equity, and
income and cash flows for the period from August 7, 1997 (date of inception) to
December 31, 1997 and the year ended December 31, 1998, respectively, and (ii)
an unaudited balance sheet of the Company at August 28, 1999 (the "Balance Sheet
Date") and the related unaudited statements of income and cash flows for the
eight months then ended. The financial statements referred to in this Section
6.1(e) (the "Financial Statements") fairly present the consolidated financial
position and the consolidated results of operations of the business of the
Company as of the dates thereof and for the periods then ended. The Financial
Statements have been prepared, in each case, in accordance with GAAP
consistently applied during the periods involved, except as may be noted
therein.

     (f) Absence of Certain Changes.  Since December 31, 1998, the Company has
conducted its business only in, and has not engaged in any transaction other
than according to, the ordinary and usual course of such business and there has
not been (i) any change in the financial condition, properties, prospects,
business or results of operations of the Company or any development or
combination of developments that is reasonably likely to have a Company Material
Adverse Effect; (ii) any damage, destruction or other casualty loss with respect
to any asset or property owned, leased or otherwise used by the Company, whether
or not covered by insurance; (iii) any declaration, setting aside or payment of
any dividend or other distribution in respect of the capital stock of the
Company; (iv) any change by the Company in accounting principles, practices or
methods; or (v) any increase, except in the ordinary course of business
consistent with past practice and consistent with Schedule 7.1(d) of the Company
Disclosure Schedule, in the compensation payable or that could become payable by
the Company to officers or key employees or any amendment of any of the
Compensation and Benefit Plans or the Stock Plan. Schedule 6.1(f) of the Company
Disclosure Schedule sets forth the name, title, salary and other compensation of
each employee of the Company as of the date of this Agreement.

     (g) Litigation and Liabilities.  There are no (i) civil, criminal or
administrative actions, suits, claims, hearings, investigations or proceedings
pending or, to the knowledge of the Company, threatened against the Company or
any of its Affiliates or (ii) obligations or liabilities, whether or not
accrued, contingent or otherwise, including those relating to matters involving
any Environmental Health and Safety Law, or any other facts or circumstances
that could result in any claims against, or obligations or liabilities of, the
Company or any of its Affiliates.

                                      A-17
<PAGE>   107

     (h) Employee Benefits.

     (i) A copy of each bonus, deferred compensation, pension, retirement,
profit-sharing, thrift, savings, employee stock ownership, stock bonus, stock
purchase, restricted stock, stock option, employment, termination, severance,
compensation, medical, health or other plan, agreement, policy or arrangement
that covers current or former employees, contractors or directors of the Company
(the "Compensation and Benefit Plans") and any trust agreement or insurance
contract forming a part of such Compensation and Benefit Plans has been made
available to Parent prior to the date hereof. The Compensation and Benefit Plans
are listed in Section 6.1(h) of the Company Disclosure Schedule and any "change
of control" or similar provisions therein are specifically identified in Section
6.1(h) of the Company Disclosure Schedule.

     (ii) All Compensation and Benefit Plans are in substantial compliance with
all applicable law, including the Code and the Employee Retirement Income
Security Act of 1974, as amended ("ERISA"). Each Compensation and Benefit Plan
that is an "employee pension benefit plan" within the meaning of Section 3(2) of
ERISA (a "Pension Plan") and that is intended to be qualified under Section
401(a) of the Code has received a favorable determination letter from the
Internal Revenue Service (the "IRS") with respect to "TRA" (as defined in
Section 1 of Rev. Proc. 93-39), and the Company is not aware of any
circumstances likely to result in revocation of any such favorable determination
letter. There is no pending or, to the knowledge of the Company, threatened
litigation relating to the Compensation and Benefit Plans. The Company has not
engaged in a transaction with respect to any Compensation and Benefit Plan that,
assuming the taxable period of such transaction expired as of the date hereof,
would subject the Company to a tax or penalty imposed by either Section 4975 of
the Code or Section 502 of ERISA.

     (iii) As of the date hereof, no liability under Subtitle C or D of Title IV
of ERISA has been or is expected to be incurred by the Company with respect to
any ongoing, frozen or terminated "single-employer plan", within the meaning of
Section 4001(a)(15) of ERISA, currently or formerly maintained by any of them,
or the single-employer plan of any entity which is considered one employer with
the Company under Section 4001 of ERISA or Section 414 of the Code (an "ERISA
Affiliate"). The Company has not contributed, or been obligated to contribute,
to a multiemployer plan under Subtitle E of Title IV of ERISA at any time since
September 26, 1980. No notice of a "reportable event", within the meaning of
Section 4043 of ERISA for which the 30-day reporting requirement has not been
waived, has been required to be filed for any Pension Plan or by any ERISA
Affiliate within the 12-month period ending on the date hereof or will be
required to be filed in connection with the transactions contemplated by this
Agreement and the Stock Option Agreement.

     (iv) All contributions required to be made under the terms of any
Compensation and Benefit Plan as of the date hereof have been timely made or
have been reflected on the Financial Statements. Neither any Pension Plan nor
any single-employer plan of an ERISA Affiliate has an "accumulated funding
deficiency" (whether or not waived) within the meaning of Section 412 of the
Code or Section 302 of ERISA. The Company has not provided, nor is it required
to provide, security to any Pension Plan or to any single-employer plan of an
ERISA Affiliate pursuant to Section 401(a)(29) of the Code.

     (v) Under each Pension Plan which is a single-employer plan, as of the last
day of the most recent plan year ended prior to the date hereof, the actuarially
determined present value of all "benefit liabilities", within the meaning of
Section 4001(a)(16) of ERISA (as determined on the basis of the actuarial
assumptions contained in the Pension Plan's most recent actuarial valuation),
did not exceed the then current value of the assets of such Pension Plan, and
there has been no change in the financial condition of such Pension Plan since
the last day of the most recent plan year.

                                      A-18
<PAGE>   108

     (vi) The Company does not have any obligations for retiree health and life
benefits under any Compensation and Benefit Plan, except as set forth in the
Company Disclosure Schedule, or as required by Law. The Company may amend or
terminate any such plan under the terms of such plan at any time without
incurring any liability thereunder except as required by Law.

     (vii) The consummation of the Merger and the other transactions
contemplated by this Agreement or the Stock Option Agreement will not (x)
entitle any employees of the Company to severance pay, (y) accelerate the time
of payment or vesting or trigger any payment of compensation or benefits under,
increase the amount payable or trigger any other obligation pursuant to, any of
the Compensation and Benefit Plans or (z) result in any breach or violation of,
or a default under, any of the Compensation and Benefit Plans.

     (viii) None of the Company's existing or former contractors are, or may be
considered under any Law, employees of the Company.

     (ix) All Compensation and Benefit Plans covering current or former non-U.S.
employees or former employees of the Company comply in all respects with
applicable local law. The Company has no unfunded liabilities with respect to
any Pension Plan that covers such non-U.S. employees.

     (i) Compliance; Permits.  The business of the Company has not been, and is
not being, conducted in violation of any Laws. No investigation or review by any
Governmental Entity with respect to the Company is pending or, to the knowledge
of the Company, threatened, nor has any Governmental Entity indicated an
intention to conduct the same. To the knowledge of the Company, no change is
required in the Company's processes, properties or procedures in connection with
any Laws, and the Company has not received any notice or communication of any
noncompliance with any Laws. The Company has all permits, licenses, franchises,
variances, exemptions, orders and other governmental authorizations, consents
and approvals necessary to conduct its business as presently conducted.

     (j) Takeover Statutes.  No "fair price," "moratorium," "control share
acquisition" or other similar anti-takeover statute or regulation (including,
without limitation, Chapters 110C, 110D, 110 E and 110F of the General Laws of
the Commonwealth of Massachusetts) (each a "Takeover Statute") or any
anti-takeover provision in the Company's Organizational Documents is, or at the
Effective Time will be, applicable to the Company, the Shares, the Merger or the
other transactions contemplated by this Agreement, the Stock Option Agreement or
the Stockholder Voting Agreements.

     (k) Environmental Matters.  Except as set forth in Schedule 6.1(k) of the
Company Disclosure Schedule: (i) the Company has complied at all times with all
applicable Environmental Health and Safety Laws; (ii) to the knowledge of the
Company no property currently owned or operated by the Company (including soils,
groundwater, surface water, buildings or other structures) is contaminated with
any Hazardous Substance; (iii) to the knowledge of the Company no property
formerly owned or operated by the Company was contaminated with any Hazardous
Substance during or prior to such period of ownership or operation; (iv) to the
knowledge of the Company the Company is not subject to liability for any
Hazardous Substance disposal or contamination on any third party property; (v)
the Company has not been associated with any release or threat of release of any
Hazardous Substance; (vi) the Company has not received any notice, demand,
letter, claim or request for information alleging that the Company may be in
violation of or subject to liability under any Environmental Health and Safety
Law; (vii) the Company is not subject to any order, decree, injunction or other
agreement with any Governmental Entity or any indemnity or other agreement with
any third party relating to liability under any Environmental Health and Safety
Law or relating to Hazardous Substances; (viii) to the knowledge of the Company
there are no other circumstances or conditions involving the Company that could
reasonably be expected to result in any claim,

                                      A-19
<PAGE>   109

liability, investigation, cost or restriction on the ownership, use, or transfer
of any property pursuant to any Environmental Health and Safety Law; and (ix)
the Company has delivered to Parent copies of all written environmental reports,
studies, assessments, sampling data and other environmental information in its
possession relating to the Company or its current and former properties or
operations.

     (l) Accounting and Tax Matters.  (i) Neither the Company nor any of its
Affiliates has taken or agreed to take any action, nor does the Company have any
knowledge of any fact or circumstance, that would prevent Parent from accounting
for the business combination to be effected by the Merger as a
"pooling-of-interests" or prevent the Merger and the other transactions
contemplated by this Agreement from qualifying as a "reorganization" within the
meaning of Section 368(a) of the Code.

     (ii) The representations and warranties that are set forth in the Company's
letter to be delivered by the Company to Ernst & Young LLP in connection with
Section 8.1(e) are hereby adopted as if such representations and warranties were
fully set forth herein; provided that no representation or warranty is made to
the extent such representation or warranty relates to Parent.

     (m) Taxes.  The Company (i) has prepared in good faith and duly and timely
filed (taking into account any extension of time within which to file) all Tax
Returns required to be filed by it and all such filed Tax Returns are complete
and accurate; (ii) has paid or accrued all Taxes that are required to be paid or
accrued and has withheld from amounts owing to any employee, creditor or third
party all amounts that the Company is obligated to withhold, except in each case
with respect to matters contested in good faith; and (iii) has not waived any
statute of limitations with respect to Taxes or agreed to any extension of time
with respect to a Tax assessment or deficiency. As of the date hereof, there are
not ongoing or, to the knowledge of the Company threatened in writing, any
audits, examinations, investigations or other proceedings in respect of Taxes or
Tax matters which could result in any tax deficiency of the Company for any
taxable period ending on or before the date hereof, and the Company is not aware
of any reasonable basis upon which any such deficiency would be asserted. There
are no liens on any of the Company's assets that arose in connection with any
failure (or alleged failure) to pay any Tax other than liens for Taxes not yet
due or being contested in good faith by appropriate proceedings. The Company has
never been a party to the filing of an affiliated, combined, consolidated or
unitary Tax Return. No closing agreements, private letter rulings, technical
advice memoranda or similar agreements or rulings have been entered into or
issued by any taxing authority with respect to the Company. Except as set forth
in the Company Disclosure Schedule, the Company will not, as a result of the
transactions contemplated by this Agreement, be obligated to make a payment that
will not be deductible under Section 280G of the Code. The Company has made
available to Parent true and correct copies of the United States federal income
Tax Returns filed by the Company for each of the fiscal years ended December 31,
1997 and 1998. The Company has not been audited by any Governmental Entity in
respect of Taxes or Tax matters. The Company does not have any liability with
respect to income, franchise or similar Taxes that accrued on or before the
Balance Sheet Date in excess of the amounts accrued with respect thereto that
are reflected in the Financial Statements.

     (n) Labor Matters.  The Company is not a party to or otherwise bound by any
collective bargaining agreement, contract or other agreement or understanding
with a labor union or labor organization, nor is the Company the subject of any
proceeding asserting that the Company has committed an unfair labor practice or
is seeking to compel it to bargain with any labor union or labor organization
nor is there pending or, to the knowledge of the Company, threatened, nor has
there been, since the date of the Company's formation, any labor strike,
dispute, walk-out, work stoppage, slow-down or lockout involving the Company.

                                      A-20
<PAGE>   110

     (o) Insurance.

     (i) The Company has delivered to Parent true and complete copies of all
policies of insurance to which the Company is a party or under which any
director of the Company is insured.

     (ii) All insurance policies maintained by the Company are with reputable
insurance carriers, provide full and adequate coverage for all normal risks
incident to the business of the Company and its properties and assets.

     (iii) The Company has paid all premiums due, and has otherwise performed
all of its obligations under each insurance policy to which the Company is a
party or that provides coverage to any director of the Company and all such
insurance policies shall continue in full force and effect following the
consummation of the transactions contemplated by this Agreement.

     (p) Intellectual Property.

     (i) Set forth in Schedule 6.1(p)(i) of the Company Disclosure Schedule is a
complete list of each of the following items (A) all patents and applications
therefor, registrations of trademarks (including service marks) and applications
therefor, and registrations of copyrights and applications therefor that are
owned by the Company or licensed to the Company (collectively, "Company
Intellectual Property Rights"), (B) all licenses, sublicenses, agreements and
contracts relating to the Company Intellectual Property pursuant to which the
Company is entitled to use any Company Intellectual Property owned by any third
party ("Third Party Intellectual Property Licenses") excluding commercially
available end-user computer software licenses, where the total license fees for
such software do not exceed $10,000 per license per calendar year, used in the
normal course of business ("Commercial Software Licenses") and (C) all
agreements under which the Company has granted any third party the right to use
any Company Intellectual Property.

     (ii) To the knowledge of the Company, excluding Commercial Software
Licenses the Company is the owner of all intellectual property, including,
without limitation, all Company Intellectual Property Rights, patents and patent
applications, supplementary protection certificates and patent extensions,
trademarks and trademark applications, service mark and service mark
registrations, logos, commercial symbols, business name registrations, trade
names, copyrights and copyright registrations, computer software, mask works and
mask work registration applications, industrial designs and applications for
registration of such industrial designs, including, without limitation, any and
all applications for renewal, extensions, reexaminations and reissues of any of
the foregoing intellectual property rights where applicable, inventions,
biological materials, trade secrets, formulae, know-how, technical information,
research data, research raw data, laboratory notebooks, procedures, designs,
proprietary technology and information held or used in the business of the
Company (the "Company Intellectual Property").

     (iii) To the knowledge of the Company, (a) the Company is the sole legal
and beneficial owner of all the Company Intellectual Property (except for
Company Intellectual Property that is the subject of any Third Party
Intellectual Property Licenses or the Commercial Software Licenses) and (b) all
Company Intellectual Property is valid and subsisting.

     (iv) The Company has not entered into any agreements, licenses or created
any Encumbrances, leases, equities, options, restrictions, rights of first
refusal, title retention agreements or other exceptions to title which affect
the Company Intellectual Property or restrict the use by the Company of the
Company Intellectual Property in any way.

     (v) The Company is in compliance in all respects with Third Party
Intellectual Property Licenses.

     (vi) The Company is not, and will not be as a result of the execution,
delivery or performance of this Agreement or the consummation of the Merger or
the other transactions contemplated hereby
                                      A-21
<PAGE>   111

in breach, violation or default of any Third Party Intellectual Property
Licenses. The rights of the Company to the Company Intellectual Property will
not be affected by the execution, delivery or performance of this Agreement or
the consummation of the Merger or the other transactions contemplated hereby.

     (vii) The Company has the right to license to third parties the use of
Company Intellectual Property Rights.

     (viii) All registrations and filings relating to Company Intellectual
Property Rights are in good standing. All maintenance and renewal fees necessary
to preserve the rights of the Company in respect of Company Intellectual
Property Rights have been made. The registrations and filings relating to
Company Intellectual Property Rights are proceeding and there are no facts of
which the Company has knowledge which could significantly undermine those
registrations or filings or reduce to a significant extent the scope of
protection of any patents arising from such applications beyond that which
ordinarily might occur in a patent prosecution proceeding.

     (ix) The manufacturing, marketing, distribution or sale of any product
currently manufactured, marketed, distributed or sold by, or identified for
development by, the Company, licensees or sublicensees in the countries where
the Company has conducted or proposes to conduct such activities, to the
knowledge of the Company, does not and would not infringe, induce infringement
or contributorily infringe the patents, patent applications, trademarks,
trademark applications, service marks, service mark applications, copyrights,
copyright applications, and proprietary trade names, publication rights,
computer programs (including source code and object code), inventions, know-
how, trade secrets, technology, processes, confidential information and all
other intellectual property rights throughout the world (collectively,
"Intellectual Property Rights") of any third party.

     (x) To the knowledge of the Company, there are no allegations, claims or
proceedings instituted or pending which challenge the rights possessed by the
Company to use the Company Intellectual Property or the validity or
effectiveness of the Company Intellectual Property, including without limitation
any interferences, oppositions, cancellations or other contested proceedings.

     (xi) To the knowledge of the Company, there are no outstanding claims or
proceedings instituted or pending by any third party challenging the ownership,
priority, scope or validity or effectiveness of any Company Intellectual
Property.

     (xii) To the knowledge of the Company, there are no Intellectual Property
Rights of any third party that would be infringed by the continued practice of
any technologies previously used or presently in use by the Company.

     (xiii) To the knowledge of the Company, there is no unauthorized use,
infringement or misappropriation of the Company Intellectual Property by any
third party, including any employee or former employee of the Company.

     (xiv) The Company has not granted any licenses, immunities, options or
other rights to the Company Intellectual Property which could provide a third
party with a defense to patent infringement proceedings, whether domestic or
foreign.

     (xv) The Company has taken commercially reasonable measures to maintain the
confidentiality of the inventions, trade secrets, formulae, know-how, technical
information, research data, research raw data, laboratory notebooks, procedures,
designs, proprietary technology and information of the Company, and all other
information the value of which to the Company is contingent upon maintenance of
the confidentiality thereof. Without limiting the generality of the foregoing,
(A) each employee of the Company and each consultant to the Company who has had
access to proprietary information with respect to the Company has entered into
an agreement suitable to vest ownership rights to any inventions, creations,
developments, and works in the Company and has entered into an

                                      A-22
<PAGE>   112

agreement for maintaining the confidential information of the Company and (B)
each officer and director of the Company has entered into an agreement to
maintain the confidential information of the Company, except for those
individuals listed in Schedule 6.1(p)(xv) of the Company Disclosure Schedule
whose involvement in the business of the Company is described with specificity
therein.

     (q) Year 2000 Compliance.  (i) Items of hardware, software, firmware or
embedded processes ("Systems") that are a part of, or are used in connection
with, the business of the Company will be Year 2000 Compliant by December 31,
1999, (disregarding insurance or similar coverage or plans for making such
Systems Year 2000 Compliant).

     (ii) Based upon a reasonable inquiry of substantial suppliers, customers
and service providers of the Company, to the knowledge of the Company, no
supplier, customer or service provider of the Company will be unable to ensure
that its Systems are Year 2000 Compliant.

     (r) Title to Properties; Encumbrances.  The Company does not own any real
property. Schedule 6.1(r) of the Company Disclosure Schedule contains a complete
and accurate list of all real property leases to which the Company is a party.
The Company owns (i) all of the properties and assets (whether real, personal,
or mixed and whether tangible or intangible) that it purports to own, including
all of the properties and assets reflected in the Financial Statements and (ii)
all of the properties and assets purchased or otherwise acquired by the Company
since the Balance Sheet Date, except for personal property acquired and sold
since such date in the ordinary course of business and consistent with past
practice, which subsequently purchased or acquired properties and assets are
listed in Schedule 6.1(r) of the Company Disclosure Schedule. All of the
aforementioned properties and assets, taken together, are the only properties
and assets used in conducting the businesses of the Company, and such properties
and assets are adequate for the continued operation of such businesses after the
Closing in substantially the same manner as conducted to the date hereof. All
properties and assets reflected in the Financial Statements are free and clear
of all Encumbrances except as reflected in the Financial Statements or Schedule
6.1(r) of the Company Disclosure Schedule.

     (s) Contracts.  Schedule 6.1(s) of the Company Disclosure Schedule lists
the following Contracts to which the Company is a party on the date hereof:

          (i) any agreement the performance of which involved aggregate
     consideration in excess of $25,000.00 during 1998 or 1999;

          (ii) any Contract of the Company the performance of which involved
     aggregate consideration in excess of $250,000.00;

          (iii) any employment agreement;

          (iv) any agreement which relates to indebtedness owed by the Company,
     or the guarantee thereof excluding purchases of parts or equipment in the
     ordinary course of the Company's business consistent with past practice;

          (v) all broker, distributor, dealer, manufacturer's representative,
     franchise, agency, sales promotion, market research, marketing consulting
     and advertising Contracts and agreements to which the Company is a party;

          (vi) all Contracts with independent contractors or consultants to
     which the Company is a party and which are not cancellable without penalty
     or further payment and without more than 30 days' notice;

          (vii) all Contracts with any Governmental Entity to which the Company
     or its Subsidiary is a party;

          (viii) all Contracts that limit or purport to limit the ability of the
     Company to compete in any line of business or with any Person or in any
     geographic area or during any period of time;

                                      A-23
<PAGE>   113

          (ix) all Contracts between or among the Company and any senior
     executive officer or director of the Company;

          (x) all Contracts to which the Company is expressly subject by the
     terms of the Contract to confidentiality obligations; and

          (xi) any other Contracts which are material to the Company the absence
     of which would have a Company Material Adverse Effect.

Except for those Contracts specified on the Company Disclosure Schedule as
Contracts under clause (x) above, the Company has made available to Parent a
correct and complete copy of each Contract listed in Schedule 6.1(s) of the
Company Disclosure Schedule, together with any and all amendments or
modifications thereto. Each such Contract is valid, binding, enforceable, and in
full force and effect, the Company is not in breach or default under any such
Contract and to the knowledge of the Company no event has occurred which, with
or without notice or lapse of time or both, would constitute a breach or
default, or permit termination, modification, or acceleration, under such
Contract.

     (t) Condition and Sufficiency of Assets.  The buildings, plants, structures
and equipment of the Company are structurally sound, are in good operating
condition and repair, and are adequate for the uses to which they are being put,
and none of such buildings, plants, structures or equipment is in need of
maintenance or repairs except for ordinary, routine maintenance and repairs. The
building, plants, structures and equipment of the Company are sufficient for the
continued operation of the Company's businesses after the Closing in
substantially the same manner as conducted to the date hereof. To the knowledge
of the Company, the Company has all easements, rights of way and other real
property rights which are necessary for the ownership, use and operation of its
properties, assets and business.

     (u) Certain Payments.  No director, officer, agent, or employee of the
Company, or any other Person associated with or acting for or on behalf of the
Company, has directly or indirectly (a) made any contribution, gift, bribe,
rebate, payoff, influence payment, kickback, or other payment to any Person,
private or public, regardless of form, whether in money, property, or services
(i) to obtain favorable treatment in securing business or (ii) in violation of
any Law, or (b) established or maintained any fund or asset that has not been
recorded in the books and records of the Company.

     (v) Disclosure.  (i) No representation or warranty of the Company contained
in this Agreement or the Company Disclosure Schedule contains any untrue
statement of a material fact, or omits to state any material fact, which is
required to be stated herein or therein, or is necessary, in order to make the
statements contained herein or therein not misleading.

     (ii) There is no fact known to the Company that has specific application to
the Company (other than general economic or industry conditions) and that
adversely affects the assets, business, prospects, financial condition, or
results of operations of the Company that has not been set forth in this
Agreement or the Company Disclosure Schedule.

     (w) Books and Records.  The books of account, minute books, stock record
books, and other records of the Company, all of which have been made available
to Parent, are complete and correct, in all material respects, and have been
maintained in accordance with sound business practices. The minute books of the
Company contain accurate and complete records, in all material respects, of all
meetings held by, and corporate action taken by, the stockholders, the boards of
directors, and committees of the boards of directors of the Company, and no
meeting of any such stockholders, board of directors or committee has been held
where material matters were approved, voted upon or acted upon for which minutes
have not been prepared and are not contained in such minute books. At the
Closing, all of such books and records shall be in the possession of the
Company.

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<PAGE>   114

     (x) Brokers and Finders.  Neither the Company nor any of its officers,
directors or employees has employed any broker or finder or incurred any
liability for any brokerage fees, commissions or finders, fees in connection
with the Merger or the other transactions contemplated in this Agreement or the
Stock Option Agreement.

     6.2. Representations and Warranties of Parent and Merger Sub.  Parent and
Merger Sub each hereby represent and warrant to the Company that, except as set
forth in a correspondingly numbered schedule in the Parent Disclosure Schedule:

     (a) Capitalization of Parent and Merger Sub.

     (i) The authorized capital stock of Parent consists of 75,000,000 shares of
Common Stock, par value $0.01 per share, of which 25,723,402 shares were issued
and outstanding as of September 8, 1999, and 5,000,000 shares of Preferred
Stock, par value $0.01 per share, of which no shares were issued and outstanding
as of such date. All outstanding shares of Parent Common Stock are duly
authorized, validly issued, fully paid and non-assessable and are not subject to
preemptive rights created by statute, the Certificate of Incorporation or
By-laws of Parent ("Parent's Organizational Documents") or any agreement or
document to which Parent is a party or by which it is bound.

     (ii) The authorized capital stock of Merger Sub consists of 1,000 shares of
Common Stock, par value $1.00 per share, all of which are validly issued and
outstanding. All of the issued and outstanding capital stock of Merger Sub is,
and at the Effective Time will be, owned by Parent, and there are (i) no other
shares of capital stock or voting securities of Merger Sub, (ii) no securities
of Merger Sub convertible into or exchangeable for shares of capital stock or
voting securities of Merger Sub and (iii) no options or other rights to acquire
from Merger Sub, and no obligations of Merger Sub to issue, any capital stock,
voting securities or securities convertible into or exchangeable for capital
stock or voting securities of Merger Sub. Merger Sub was formed for the specific
purpose of consummating the transactions contemplated by this Agreement, has not
conducted any business prior to the date hereof and has no, and prior to the
Effective Time will have no, assets, liabilities or obligations of any nature
other than those incident to its formation and pursuant to this Agreement and
the Merger and the other transactions contemplated by this Agreement.

     (b) Organization, Good Standing and Qualification.  Each of Parent and
Merger Sub is a corporation duly organized, validly existing and in good
standing under the laws of its respective jurisdiction of organization and has
all requisite corporate or similar power and authority to own and operate its
properties and assets and to carry on its business as presently conducted and is
qualified to do business and is in good standing as a foreign corporation in
each jurisdiction where the ownership or operation of its properties or conduct
of its business requires such qualification. Parent has made available to the
Company a complete and correct copy of Parent's Organizational Documents, each
as amended to, and in full force as of, the date hereof.

     (c) Corporate Authority.

     (i) No vote of holders of capital stock of Parent is necessary to approve
this Agreement and the Merger and the other transactions contemplated hereby.
Each of the Parent and Merger Sub has all requisite corporate power and
authority and has taken all corporate action necessary in order to execute,
deliver and perform its obligations under this Agreement and to consummate the
Merger. This Agreement is a valid and binding agreement of Parent and Merger
Sub, enforceable against each of Parent and Merger Sub in accordance with its
terms, subject to the Bankruptcy and Equity Exception.

     (ii) Prior to the Effective Time, Parent will have taken all necessary
action to permit it to issue the number of shares of Parent Common Stock
required to be issued pursuant to Article V. The

                                      A-25
<PAGE>   115

Parent Common Stock, when issued, will be validly issued, fully paid and
nonassessable, and free of any preemptive right of subscription or purchase in
respect thereof.

     (d) Governmental Filings; No Violations.  (i) Except for (A) the filing of
the Massachusetts Articles of Merger pursuant to Section 2.3, (B) filings and/or
notices under the HSR Act, the Securities Act and the Exchange Act, (C) such
consents, approvals, orders and authorizations as may be required under
applicable state securities or "blue sky" laws and (D) filings and/or notices
required to be made with NASDAQ, no notices, reports or other filings are
required to be made by Parent or Merger Sub with, nor are any consents,
registrations, approvals, permits or authorizations required to be obtained by
Parent or Merger Sub from, any Governmental Entity, in connection with the
execution and delivery of this Agreement by Parent and Merger Sub and the
consummation by Parent and Merger Sub of the Merger and the other transactions
contemplated hereby. Schedule 6.2(d) of the Parent Disclosure Schedule sets
forth a correct and complete list of Contracts of Parent or Parent Companies
pursuant to which waivers or consents may be required prior to consummation of
the transactions contemplated by this Agreement.

     (ii) The execution, delivery and performance of this Agreement by Parent
and Merger Sub do not, and the consummation by Parent and Merger Sub of the
Merger and the other transactions contemplated hereby will not, constitute or
result in (A) a breach or violation of, or a default under, the Organizational
Documents of Parent and Merger Sub, (B) a breach or violation of, or a default
under, the acceleration of any obligations or the creation of any Encumbrance on
the assets of Parent or any of its Subsidiaries (with or without notice, lapse
of time or both) pursuant to, any Contracts binding upon Parent or any of its
Subsidiaries or any Law or governmental or non-governmental permit or license to
which Parent or any of its Subsidiaries is subject or (C) any change in the
rights or obligations of any party under any of the Contracts binding upon
Parent.

     (e) Parent Reports; Financial Statements.  Parent has made available to the
Company (i) Parent's Annual Report on Form 10-K for the year ended December 31,
1998, (ii) Parent's Quarterly Reports on Form 10-Q for the periods ended March
31, 1999 and June 30, 1999 and (iii) Parent's registration statements on Form
S-3 since December 31, 1998 each in the form (including exhibits, annexes and
any amendments thereto) filed with the SEC (collectively, including any such
reports filed subsequent to the date hereof, the "Parent Reports"). Parent has
timely filed, and between the date of this Agreement and the Effective Time will
timely file, with the SEC all forms, documents and reports required to be filed
with the SEC. As of their respective dates, the Parent Reports (i) complied in
all material respects, and all reports filed by Parent with the SEC between the
date of this Agreement and the Effective Time will comply in all material
respects, with applicable SEC requirements and (ii) did not, and any Parent
Reports filed with the SEC subsequent to the date hereof will not, contain any
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements made therein, in light of
the circumstances in which they were made, not misleading. Each of the
consolidated balance sheets included in or incorporated by reference into the
Parent Reports (including the related notes and schedules) fairly presents, or
will fairly present, the consolidated financial position of Parent and its
Subsidiaries as of its date and each of the consolidated statements of income
and of changes in financial position included in or incorporated by reference
into the Parent Reports (including any related notes and schedules) fairly
presents, or will fairly present, the results of operations, retained earnings
and changes in financial position, as the case may be, of Parent and its
Subsidiaries for the periods set forth therein (subject, in the case of
unaudited statements, to notes and normal year-end audit adjustments that will
not be material in amount or effect), in each case in accordance with GAAP
consistently applied during the periods involved, except as may be noted
therein.

     (f) Accounting and Tax Matters.  (i) As of the date hereof, neither Parent
nor any of its Affiliates has taken or agreed to take any action, nor does
Parent have any knowledge of any fact or

                                      A-26
<PAGE>   116

circumstance, that would prevent Parent from accounting for the business
combination to be effected by the Merger as a "pooling-of-interests" or prevent
the Merger and the other transactions contemplated by this Agreement from
qualifying as a "reorganization" within the meaning of Section 368(a) of the
Code.

     (ii) The representations and warranties that are set forth in Parent's
letter to be delivered by Parent to Ernst & Young LLP in connection with section
8.1(e) are hereby adopted as if such representations and warranties were fully
set forth herein; provided, that no representation or warranty is made to the
extent such representation or warranty relates in any respect to the Company.

     (g) No Parent Material Adverse Effect.  Except as set forth in the Parent
Reports, since June 30, 1999 there has not been any change in the financial
condition, business or results of operations of Parent or any development or
combination of developments that is reasonably likely to have a Parent Material
Adverse Effect; it being understood among the parties to this Agreement, that
for purposes of this Section 6.2(g), any change in the trading price of the
shares of Parent Common Stock, or change in financial or economic markets which
effects the trading price on the NASDAQ of the shares of Parent Common Stock
shall not be considered when determining if a Parent Material Adverse Effect has
occurred.

     (h) Brokers and Finders.  Neither Parent nor any of its officers, directors
or employees has employed any broker or finder or incurred any liability for any
brokerage fees, commissions or finders, fees in connection with the Merger or
the other transactions contemplated by this Agreement.

                                  ARTICLE VII

                                   COVENANTS

     7.1.  Interim Operations of the Company.  The Company covenants and agrees
that, after the date hereof and prior to the Effective Time (unless Parent shall
otherwise approve in writing and except as otherwise expressly contemplated by
this Agreement and the Stock Option Agreement):

          (a) except as specifically provided in Section 7.1(a) of the Company
     Disclosure Schedule, the business of the Company shall be conducted in the
     ordinary and usual course and, to the extent consistent therewith, it shall
     use its commercially reasonable best efforts to preserve its business
     organization intact and maintain its existing relations and goodwill with
     customers, suppliers, distributors, creditors, lessors, employees and
     business associates;

          (b) it shall not (i) amend its Organizational Documents; (ii) split,
     combine or reclassify its outstanding shares of capital stock; (iii)
     declare, set aside or pay any dividend payable in cash, stock or property
     in respect of any capital stock; or (iv) repurchase, redeem or otherwise
     acquire any shares of its capital stock or any securities convertible into
     or exchangeable or exercisable for any shares of its capital stock;

          (c) it shall not (i) issue, sell, pledge, dispose of or encumber any
     shares of, or securities convertible into or exchangeable or exercisable
     for, or options, warrants, calls, commitments or rights of any kind to
     acquire, any shares of its capital stock of any class or any Voting Debt or
     any other property or assets (other than Shares issuable pursuant to (A)
     outstanding options on the date hereof under the Stock Plan, (B)
     Outstanding Warrants or (C) Company Options issued in the ordinary and
     usual course of business between the date of this Agreement and the
     Effective Time); (ii) other than in the ordinary and usual course of
     business, transfer, lease, license, guarantee, sell, mortgage, pledge,
     dispose of or encumber any other property or assets or incur or modify any
     material indebtedness or other liability; provided, however, that the
     Company may borrow funds from a bank or other financial lending institution
     for general working capital purposes not to exceed $250,000 in the
     aggregate for non-inventory expenditures

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<PAGE>   117

     and $500,000 in the aggregate for non-inventory and inventory expenditures
     taken together; (iii) make or authorize or commit for any capital
     expenditures, other than in the ordinary course of business and pursuant to
     the calendar years 1999 and 2000, capital appropriations/spending budgets
     set forth in the Company Disclosure Schedule, and in no event shall any
     capital expenditures exceed $50,000 individually or $200,000 in the
     aggregate; or (iv) by any means, make any acquisition of, or investment in,
     assets or stock of any other Person or entity;

          (d) it shall not terminate, establish, adopt, enter into, make any new
     grants or awards under (except pursuant to normal advancement and promotion
     procedure consistent with past practice and as set forth in Schedule 7.1(d)
     of the Company Disclosure Schedule), amend or otherwise modify, any
     Compensation and Benefit Plans or increase the salary, wage, bonus or other
     compensation of any employees;

          (e) it shall not settle or compromise any material claims or
     litigation or, except in the ordinary and usual course of business, modify,
     amend or terminate any of its material Contracts or waive, release or
     assign any material rights or claims;

          (f) it shall not make any material Tax election or permit any
     insurance policy naming it as a beneficiary or loss-payable payee to be
     cancelled or terminated except in the ordinary and usual course of
     business;

          (g) it shall not change any of the accounting practices or principles
     used by it other than is required by GAAP if the Company makes such change
     pursuant to and in accordance with the written advice of Ernst & Young LLP;

          (h) it shall not adopt a plan of complete or partial liquidation,
     dissolution, merger, consolidation, restructuring, recapitalization or
     other reorganization of the Company;

          (i) it shall not take any action or omit to take any action that would
     cause any of its representations and warranties herein to become untrue in
     any material respect; and

          (j) it shall not authorize or enter into an agreement to do any of the
     foregoing.

     7.2.  Acquisition Proposals.  The Company agrees that neither it nor any of
the officers and directors of it shall, and that it shall direct and use its
best efforts to cause its employees, agents and representatives (including any
investment banker, attorney or accountant retained by it) not to, directly or
indirectly, initiate, solicit, encourage or otherwise facilitate any inquiries
or the making of any proposal or offer with respect to a merger, reorganization,
share exchange, consolidation or similar transaction involving, or any purchase
of 10% or more (or any percentage that would negatively effect the ability of
the Merger to qualify for pooling of interests accounting treatment) of the
assets or any equity securities of, the Company (any such proposal or offer
being hereinafter referred to as an "Acquisition Proposal"). The Company further
agrees that neither it nor any of the officers and directors of it shall, and
that it shall direct and use its best efforts to cause its employees, agents and
representatives (including any investment banker, attorney or accountant
retained by it) not to, directly or indirectly, engage in any negotiations
concerning, or provide any confidential information or data to, or have any
discussions with, any Person relating to an Acquisition Proposal, or otherwise
facilitate any effort or attempt to make or implement an Acquisition Proposal;
provided, however, that nothing contained in this Agreement shall prevent the
Company or its Board of Directors from (i) providing information in response to
a request therefor by a Person who has made an unsolicited bona fide written
Acquisition Proposal if the Board of Directors receives from the Person so
requesting such information an executed confidentiality agreement; (ii) engaging
in any negotiations or discussions with any Person who has made an unsolicited
bona fide written Acquisition Proposal; or (iii) recommending such an
Acquisition Proposal to the stockholders of the Company, if and only to the
extent that, (A) in each such case referred to in clause (i), (ii) or (iii)
above, the Board of

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<PAGE>   118

Directors of the Company determines in good faith after consultation with
outside legal counsel that such action is necessary in order for its directors
to comply with their respective fiduciary duties under applicable law and (B) in
each case referred to in clause (ii) or (iii) above, the Board of Directors of
the Company determines in good faith (after consultation with its financial
advisor) that such Acquisition Proposal, if accepted, is reasonably likely to be
consummated, taking into account all legal, financial and regulatory aspects of
the proposal and the Person making the proposal and would, if consummated,
result in a transaction more favorable to the Company's stockholders from a
financial point of view than the transaction contemplated by this Agreement (any
such more favorable Acquisition Proposal being referred to in this Agreement as
a "Superior Proposal"). The Company agrees that it will immediately cease and
cause to be terminated any existing activities, discussions or negotiations with
any parties, other than Parent or Merger Sub, conducted heretofore with respect
to any Acquisition Proposal. The Company agrees that it will take the necessary
steps to promptly inform the individuals or entities referred to in the first
sentence hereof of the obligations undertaken in this Section 7.2. The Company
agrees that it will notify Parent immediately if any such inquiries, proposals
or offers are received by, any such information is requested from, or any such
discussions or negotiations are sought to be initiated or continued with, any of
its representatives indicating, in connection with such notice, the name of such
Person and the material terms and conditions of any proposals or offers and
thereafter shall keep Parent informed, on a current basis, on the status and
terms of any such proposals or offers and the status of any such discussions or
negotiations. The Company also agrees that it will promptly request each Person
that has heretofore executed a confidentiality agreement in connection with its
consideration of acquiring it to return all confidential information heretofore
furnished to such Person by or on behalf of it.

     7.3.  Information Supplied.  The Company and Parent each agrees that none
of the information supplied or to be supplied by it for inclusion or
incorporation by reference in (i) the Registration Statement on Form S-4 to be
filed with the SEC by Parent in connection with the issuance of shares of Parent
Common Stock in the Merger (including the proxy statement and prospectus (the
"Prospectus/Proxy Statement") constituting a part thereof) (the "S-4
Registration Statement") will, at the time the S-4 Registration Statement
becomes effective under the Securities Act, contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary to make the statements therein, in light of the circumstances under
which they were made, not misleading, and (ii) the Prospectus/Proxy Statement
and any amendment or supplement thereto will, at the date of mailing to
stockholders and at the times of the meetings of stockholders of the Company to
be held in connection with the Merger, contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary in order to make the statements therein, in light of the
circumstances under which they were made, not misleading.

     7.4.  Stockholders Meeting.  The Company shall take, in accordance with
applicable law and its Organizational Documents, all action necessary to convene
a meeting of holders of Shares (the "Stockholders Meeting") as promptly as
practicable after the S-4 Registration Statement is declared effective to
consider and vote upon the approval of this Agreement. Subject to fiduciary
obligations under applicable law, the Company's board of directors shall
recommend such approval and shall take all lawful action to solicit such
approval.

     7.5.  Filings; Other Actions.  (a) Parent and the Company shall prepare and
file with SEC the Prospectus/Proxy Statement and the S-4 Registration Statement
as promptly as practicable after the date hereof. Parent and the Company each
shall use its commercially reasonable best efforts to have the S-4 Registration
Statement declared effective under the Securities Act as promptly as practicable
after such filing, and promptly thereafter mail the Prospectus/Proxy Statement,
to the stockholders of the Company. Parent shall also use its commercially
reasonable best efforts to obtain all necessary state securities law or "blue
sky" permits and approvals required in connection with the Merger and

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<PAGE>   119

to consummate the other transactions contemplated by this Agreement and the
Stock Option Agreement and shall pay all expenses incident thereto.

     (b) The Company and Parent each shall use its commercially reasonable best
efforts (which efforts shall include, without limitation, the execution of
customary representation letters) to cause to be delivered to the other party
and its directors a letter of its independent auditors, dated (i) the date on
which the S-4 Registration Statement shall become effective and (ii) the Closing
Date, and addressed to the other party and its directors, in form and substance
customary for "comfort" letters delivered by independent public accountants in
connection with registration statements similar to the S-4 Registration
Statement.

     (c) The Company and Parent shall cooperate with each other and use (and
shall cause their respective Subsidiaries to use) their respective commercially
reasonable best efforts to take or cause to be taken all actions, and do or
cause to be done all things, necessary, proper or advisable on its part under
this Agreement, the Stock Option Agreement and applicable Laws to consummate and
make effective the Merger and the other transactions contemplated by this
Agreement and the Stock Option Agreement as soon as practicable, including
preparing and filing as promptly as practicable all documentation to effect all
necessary notices, reports and other filings and to obtain as promptly as
practicable all consents, registrations, approvals, permits and authorizations
necessary or advisable to be obtained from any third party and/or any
Governmental Entity in order to consummate the Merger or any of the other
transactions contemplated by this Agreement and the Stock Option Agreement;
provided, however, that nothing in this Section 7.5 shall require, or be
construed to require, Parent to proffer to, or agree to, sell or hold separate
and agree to sell, before or after the Effective Time, any assets, businesses,
or interest in any assets or businesses of Parent, the Company or any of their
respective Affiliates (or to consent to any sale, or agreement to sell, by the
Company of any of its assets or businesses) or to agree to any material changes
or restriction in the operations of any such assets or businesses. Subject to
applicable laws relating to the exchange of information, Parent and the Company
shall have the right to review in advance, and to the extent practicable each
will consult the other on, all the information relating to Parent or the
Company, as the case may be, and any of their respective Subsidiaries, that
appear in any filing made with, or written materials submitted to, any third
party and/or any Governmental Entity in connection with the Merger and the other
transactions contemplated by this Agreement and the Stock Option Agreement. In
exercising the foregoing right, each of the Company and Parent shall act
reasonably and as promptly as practicable.

     (d) The Company and Parent each shall, upon request by the other, furnish
the other with all information concerning itself, its directors, officers and
stockholders and such other matters as may be reasonably necessary or advisable
in connection with the S-4 Registration Statement, Prospectus/ Proxy Statement,
or any other statement, filing, notice or application made by or on behalf of
Parent, the Company or any of their respective Subsidiaries to any third party
and/or any Governmental Entity in connection with the Merger and the
transactions contemplated by this Agreement and the Stock Option Agreement.

     (e) The Company and Parent each shall keep the other apprised of the status
of matters relating to completion of the transactions contemplated hereby,
including promptly furnishing the other with copies of notice or other
communications received by Parent or the Company, as the case may be, from any
third party and/or any Governmental Entity with respect to the Merger and the
other transactions contemplated by this Agreement and the Stock Option
Agreement. The Company and Parent each shall give prompt notice to the other of
any development or combination of developments that, individually or in the
aggregate, is reasonably likely to result in a material adverse effect on the
financial condition, properties, prospects, business or results of operations of
the Company or Parent, as applicable.

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<PAGE>   120

     7.6.  Taxation and Accounting.  Neither Parent nor the Company shall take
or cause to be taken any action, whether before or after the Effective Time,
that would disqualify the Merger as a "pooling of interests" for accounting
purposes or as a "reorganization" within the meaning of Section 368(a) of the
Code. Each of the parties shall report the Merger for income tax purposes as a
reorganization within the meaning of Section 368(a) of the Code (and any
comparable state or local tax statute). Each of Parent and the Company shall
make and use its commercially reasonable best efforts to obtain from its
Affiliates such reasonable representations as may be requested by legal counsel
for the purpose of rendering the opinions contemplated by Section 8.1(g).

     7.7.  Access.  Upon reasonable notice and subject to the requirements of
the confidentiality provisions of those Contracts set forth on Schedule 6.1(s)
of the Company Disclosure Schedule that are specifically described on such
Schedule 6.1(s) as containing confidentiality provisions, the Company shall
afford Parent's officers, employees, counsel, accountants and other authorized
representatives ("Representatives") reasonable access, during normal business
hours throughout the period prior to the Effective Time, to its properties,
books, contracts and records and, during such period, the Company shall furnish
promptly to Parent all information concerning the Company's business, properties
and personnel as may reasonably be requested. All requests for information made
pursuant to this Section shall be directed to an executive officer of the
Company, or such Person as may be designated by the Company.

     7.8.  Affiliates.  (a) At least 10 days prior to the date of the
Stockholders Meeting, the Company shall deliver to Parent a list of names and
addresses of those Persons who are, as of the time of the Stockholders Meeting
referred to in Section 7.4, Affiliates of the Company within the meaning of Rule
145 under the Securities Act and for the purposes of applicable interpretations
regarding the pooling-of-interests method of accounting. The Company shall
provide to Parent such information and documents as Parent shall reasonably
request for purposes of reviewing such list. There shall be added to such list
the names and addresses of any other Person subsequently identified by either
Parent or the Company as a Person who may be deemed to be such an affiliate of
the Company; provided, however, that no such Person identified by Parent shall
be added to the list of affiliates of the Company if Parent shall receive from
the Company, on or before the date of the Stockholders Meeting, an opinion of
counsel reasonably satisfactory to Parent to the effect that such Person is not
such an affiliate. The Company shall exercise its commercially reasonable best
efforts to deliver or cause to be delivered to Parent, prior to the date of the
Stockholders Meeting, from each affiliate of the Company identified in the
foregoing list (as the same may be supplemented as aforesaid), a letter dated as
of the Closing Date substantially in the form attached as Exhibit A-1 (the
"Affiliates Letter"). Parent shall not be required to maintain the effectiveness
of the S-4 Registration Statement or any other registration statement under the
Securities Act for the purposes of resale of Parent Common Stock received in the
Merger and the certificates representing Parent Common Stock received by such
Affiliates shall bear a customary legend regarding applicable Securities Act
restrictions and the provisions of this Section.

     (ii) Prior to the date of the Effective Time, Parent shall deliver to the
Company a list of names and addresses of those Persons who are, in the opinion
of the Parent, Affiliates of Parent for the purposes of applicable
interpretations regarding the pooling-of-interests method of accounting. Parent
shall provide to the Company such information and documents as the Company shall
reasonably request for purposes of reviewing such list. There shall be added to
such list the names and addresses of any other Person the Company reasonably
identifies (by written notice to Parent within ten business days after the
Company's receipt of such list) as being a Person who may be deemed to be such
an affiliate of Parent; provided, however, that no such Person identified by the
Company shall be added to the list of affiliates of Parent if the Company shall
receive from Parent, on or before the date of the Stockholders Meeting, an
opinion of counsel reasonably satisfactory to the Company to the effect that
such Person is not such an affiliate. Parent shall exercise its commercially
reasonable

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<PAGE>   121

best efforts to deliver or cause to be delivered to the Company, prior to the
date of the Effective Time, from each of such affiliates of Parent identified in
the foregoing list (as the same may be supplemented as aforesaid), a letter
dated as of the Closing Date substantially in the form attached as Exhibit A-2
(the "Pooling Affiliates Letter").

     7.9.  Quotation of Parent Common Stock.  Parent shall file the appropriate
notification form for the quotation of additional shares together with the
applicable fee covering the Parent Common Stock to be issued in the Merger with
the NASDAQ prior to the Effective Time.

     7.10.  Publicity.  Parent shall control and coordinate the press relations
and publicity activities of the parties in connection with the Merger. The
Company shall consult with Parent with respect to issuing any press releases or
otherwise making public announcements with respect to the Merger and the other
transactions contemplated by this Agreement and the Stock Option Agreement and
will not issue any press releases or otherwise make any public announcements
with respect thereto without Parent's prior consent.

     7.11.  Benefits.

     (a) Stock Options.  (i) At the Effective Time, each outstanding Company
Option under the Stock Plan, whether vested or unvested, shall be deemed to
constitute an option to acquire (a "New Parent Option"), on the same terms and
conditions as were applicable under such Company Option, the same number of
shares of Parent Common Stock (rounded down to the nearest whole number) as the
holder of such Company Option would have been entitled to receive pursuant to
the Merger had such holder exercised such option in full immediately prior to
the Effective Time, at an exercise price per share (rounded up to the nearest
whole cent) equal to (y) the aggregate exercise price for the Shares otherwise
purchasable pursuant to such Company Option divided by (z) the number of full
shares of Parent Common Stock deemed purchasable pursuant to such Company Option
in accordance with the foregoing; provided, however, that in the case of any
Company Option to which Section 422 of the Code applies, the option price, the
number of shares purchasable pursuant to such option and the terms and
conditions of exercise of such option shall be determined in accordance with the
foregoing, subject to such adjustments as are necessary in order to satisfy the
requirements of Section 424(a) of the Code. At or prior to the Effective Time,
the Company shall take all necessary actions to permit the assumption of the
unexercised Company Options by Parent pursuant to this Section.

     (ii) Effective at the Effective Time, Parent shall assume, as a New Parent
Option, each outstanding Company Option in accordance with this Section and with
the terms of the Stock Plan under which it was issued and the stock option
agreement by which it is evidenced. Not later than 60 days after the Closing
Date, Parent shall file a registration statement under the Securities Act on
Form S-8, or other appropriate form, covering shares of Parent Common Stock
subject to such New Parent Options.

     (iii) In connection with Parent's assumption of Company Options in
accordance with the terms of the Stock Plan, Parent shall reserve a sufficient
number of shares of Parent Common Stock for issuance with respect to New Parent
Options.

     (b) Employee Benefits.  Parent agrees that, during the period commencing at
the Effective Time and ending on the first anniversary thereof, the employees of
the Company shall continue to be provided with benefits under employee benefit
plans (other than plans involving the issuance of Shares) that are no less
favorable in the aggregate than those currently provided by the Company to such
employees. Parent will cause such employee benefit plans to take into account
for purposes of eligibility and vesting thereunder service by employees of the
Company as if such service were with Parent. Parent shall, and shall cause the
Surviving Corporation to, honor all employee benefit obligations to current and
former employees under the Compensation and Benefit Plans and all

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employee severance plans (or policies) in existence on the date hereof and all
employment or severance agreements entered into by the Company or adopted by the
board of directors of the Company prior to the date hereof.

     7.12.  Expenses; Cash Paid to Dissenting Stockholders.  The Surviving
Corporation shall pay all charges and expenses, including those of the Exchange
Agent, in connection with the transactions contemplated in Article V, and Parent
shall reimburse the Surviving Corporation for such charges and expenses. Except
as otherwise provided in Section 9.5(b), whether or not the Merger is
consummated, all costs and expenses incurred in connection with this Agreement
and the other agreements set forth herein and the Merger and the other
transactions contemplated by this Agreement and the other agreements set forth
herein shall be paid by the party incurring such expense; provided, however,
Parent shall pay all expenses incurred in connection with the filing fee for the
S-4 Registration Statement and printing and mailing the Prospectus/Proxy
Statement and any other expenses relating to the S-4 Registration Statement. All
cash required to make payments to Dissenting Stockholders in respect of
Dissenting Shares shall originate with Parent.

     7.13.  Takeover Statutes.  If any Takeover Statute is or may become
applicable to the Merger or the other transactions contemplated by this
Agreement, the Stock Option Agreement or the Stockholder Voting Agreements, each
of Parent and the Company and its board of directors shall grant such approvals
and take such actions as are necessary so that such transactions may be
consummated as promptly as practicable on the terms contemplated by this
Agreement, the Stock Option Agreement, the Stockholder Voting Agreements or by
the Merger and otherwise act to eliminate or minimize the effects of such
statute or regulation on such transactions.

     7.14.  Warrants.  Prior to the Effective Time, the Company and Parent shall
take all action necessary to provide that on and after the Effective Time the
Warrants shall be exercisable only for the Merger Consideration.

     7.15.  Assignment of Contracts.  At the Effective Time, the Company shall
assign those non-competition and non-solicitation Contracts that the Company has
entered into with its employees, as Parent may request.

                                  ARTICLE VIII

                                   CONDITIONS

     8.1.  Conditions to Each Party's Obligation to Effect the Merger.  The
respective obligation of each party to effect the Merger is subject to the
satisfaction or waiver at or prior to the Effective Time of each of the
following conditions:

          (a) Stockholder Approval.  This Agreement shall have been duly
     approved by holders of Shares constituting the Company Requisite Vote as
     set forth in Section 6.1(c) and shall have been duly approved by the sole
     stockholder of Merger Sub in accordance with applicable law and the
     Organizational Documents of each such corporation.

          (b) NASDAQ Quotation.  The appropriate notification form for quotation
     of the shares of Parent Common Stock issuable to the Company stockholders
     pursuant to this Agreement shall have been filed with the NASDAQ and the
     applicable fee, in connection therewith, shall have been paid by Parent.

          (c) Regulatory Consents.  The waiting period applicable to the
     consummation of the Merger under the HSR Act shall have expired or been
     terminated and, other than the filing provided for in Section 2.3, all
     notices, reports and other filings required to be made prior to the
     Effective Time by the Company or Parent with, and all consents,
     registrations, approvals, permits and authorizations required to be
     obtained prior to the Effective Time by the Company or Parent

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     from, any Governmental Entity in connection with the execution and delivery
     of this Agreement and the consummation of the Merger and the other
     transactions contemplated hereby by the Company, Parent and Merger Sub
     shall have been made or obtained (as the case may be).

          (d) Litigation.  No court or Governmental Entity of competent
     jurisdiction shall have enacted, issued, promulgated, enforced or entered
     any statute, law, ordinance, rule, regulation, judgment, decree, injunction
     or other order (whether temporary, preliminary or permanent) that is in
     effect and restrains, enjoins or otherwise prohibits consummation of the
     Merger or the other transactions contemplated by this Agreement
     (collectively, an "Order"), and no Governmental Entity or any other Person
     shall have instituted any proceeding or threatened to institute any
     proceeding seeking any such Order.

          (e) Accountant Letter.  Parent and the Company shall have received a
     letter, dated as of the Closing Date, from Ernst & Young LLP regarding the
     appropriateness of pooling of interests accounting for the Merger under
     Accounting Principles Board Opinion No. 16 if closed and consummated in
     accordance with this Agreement.

          (f) S-4 Registration Statement.  The S-4 Registration Statement shall
     have become effective under the Securities Act. No stop order suspending
     the effectiveness of the S-4 Registration Statement shall have been issued,
     and no proceedings for that purpose shall have been initiated or be
     threatened, by the SEC.

          (g) Tax Opinions.  Parent and the Company shall each have received
     substantially identical written opinions from their counsel, Sullivan &
     Cromwell and Palmer & Dodge LLP, respectively, dated the Closing Date, to
     the effect that the Merger will be treated for Federal income tax purposes
     as a reorganization within the meaning of Section 368(a) of the Code, and
     that each of Parent, Merger Sub and the Company will be a party to that
     reorganization within the meaning of Section 368(b) of the Code.

     8.2.  Conditions to Obligations of Parent and Merger Sub.  The obligations
of Parent and Merger Sub to effect the Merger are also subject to the
satisfaction or waiver by Parent at or prior to the Effective Time of the
following conditions:

          (a) Representations and Warranties.  The representations and
     warranties of the Company, the stockholders set forth on the signature
     pages of this Agreement, and the Stockholder Representative (on behalf of
     the stockholders of the Company) set forth in this Agreement shall be true
     and correct in all respects as of the date of this Agreement and as of the
     Closing Date as though made on and as of the Closing Date (except to the
     extent any such representation or warranty expressly speaks as of an
     earlier date); unless the failure of any such representation or warranty to
     be so true and correct, has not had or is not reasonably likely to have, a
     Company Material Adverse Effect, and Parent shall have received a
     certificate signed on behalf of the Company by the Chief Executive Officer
     or the President of the Company to such effect.

          (b) Performance of Obligations of the Company.  The Company shall have
     performed in all material respects all obligations required to be performed
     by it under this Agreement at or prior to the Closing Date, and Parent
     shall have received a certificate signed on behalf of the Company by the
     Chief Executive Officer or the President of the Company to such effect.

          (c) Consents Under Agreements.  Except as set forth on Schedule 8.2(c)
     of the Company Disclosure Schedule, the Company shall have obtained the
     consent or approval of each Person whose consent or approval shall be
     required under any material Contract to which the Company is a party.

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          (d) Legal Opinion.  Parent shall have received an opinion of Palmer &
     Dodge LLP, counsel to the Company, dated the Closing Date, substantially in
     the form attached hereto as Exhibit B.

          (e) Resignations.  Parent shall have received the resignations of each
     director of the Company.

          (f) Non-competition Agreements.  Parent and/or Merger Sub shall have
     entered into a non-competition agreement with those individuals set forth
     in Schedule 8.2(f) of the Company Disclosure Schedule in a form
     satisfactory to Parent and each of such individuals.

          (g) Affiliates Letters.  Parent shall have received an Affiliates
     Letter from each Person identified as an affiliate of the Company pursuant
     to Section 7.8.

     8.3.  Conditions to Obligation of the Company.  The obligation of the
Company to effect the Merger is also subject to the satisfaction or waiver by
the Company at or prior to the Effective Time of the following conditions:

          (a) Representations and Warranties.  The representations and
     warranties of Parent and Merger Sub set forth in this Agreement shall be
     true and correct in all respects as of the date of this Agreement and as of
     the Closing Date as though made on and as of the Closing Date (except to
     the extent any such representation or warranty express speaks as of an
     earlier date); unless the failure of any such representation or warranty to
     be so true and correct, has not had or is not reasonable likely to have, a
     Parent Material Adverse Effect, and the Company shall have received a
     certificate signed on behalf of Parent by an executive officer of Parent to
     such effect.

          (b) Performance of Obligations of Parent and Merger Sub.  Each of
     Parent and Merger Sub shall have performed in all material respects all
     obligations required to be performed by it under this Agreement at or prior
     to the Closing Date, and the Company shall have received a certificate
     signed on behalf of Parent and Merger Sub by an executive officer of Parent
     to such effect.

          (c) Consents Under Agreements.  Parent shall have obtained the consent
     or approval of each Person whose consent or approval shall be required in
     order to consummate the transactions contemplated by this Agreement under
     any material Contract to which Parent or any of its Subsidiaries is a
     party.

          (d) Legal Opinion.  The Company shall have received an opinion of the
     General Counsel of Parent dated the Closing Date addressing the matters set
     forth in Exhibit C hereto.

                                   ARTICLE IX

                                  TERMINATION

     9.1.  Termination by Mutual Consent.  This Agreement may be terminated and
the Merger may be abandoned at any time prior to the Effective Time, whether
before or after the approval by stockholders of the Company referred to in
Section 8.1(a), by mutual written consent of the Company and Parent by action of
their respective Boards of Directors.

     9.2.  Termination by Either Parent or the Company.  This Agreement may be
terminated and the Merger may be abandoned at any time prior to the Effective
Time by action of the Board of Directors of either Parent or the Company if (i)
the Merger shall not have been consummated by February 15, 2000; (the
"Termination Date"), (ii) the approval of the Company's stockholders required by
Section 8.1(a) shall not have been obtained at a meeting duly convened therefor
or at any adjournment or postponement thereof or (iii) any Order permanently
restraining, enjoining or otherwise prohibiting consummation of the Merger shall
become final and non-appealable (whether

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before or after the approval by the stockholders of the Company); provided, that
the right to terminate this Agreement pursuant to clause (i) above shall not be
available to any party that has breached in any material respect its obligations
under this Agreement in any manner that shall have proximately contributed to
the occurrence of the failure of the Merger to be consummated.

     9.3.  Termination by the Company.  This Agreement may be terminated and the
Merger may be abandoned at any time prior to the Effective Time, whether before
or after the approval by stockholders of the Company referred to in Section
8.1(a), by action of the Board of Directors of the Company:

          (a) if (i) the Company is not in breach of any of the terms of this
     Agreement, (ii) the Board of Directors of the Company authorizes the
     Company, subject to complying with the terms of this Agreement, to enter
     into a binding written agreement concerning a transaction that constitutes
     a Superior Proposal and the Company notifies Parent in writing that it
     intends to enter into such an agreement, attaching the most current version
     of such agreement to such notice, (iii) Parent does not make, within five
     business days of receipt of the Company's written notification of its
     intention to enter into a binding agreement for a Superior Proposal, an
     offer that the Board of Directors of the Company determines, in good faith
     after consultation with its financial advisors, is at least as favorable,
     from a financial point of view, to the stockholders of the Company as the
     Superior Proposal and (iv) the Company prior to such termination pays to
     Parent in immediately available funds any fees required to be paid pursuant
     to Section 9.5. The Company agrees (x) that it will not enter into a
     binding agreement referred to above until at least the sixth business day
     after it has provided the notice to Parent required thereby and (y) to
     notify Parent promptly if its intention to enter into a written agreement
     referred to in its notification shall change at any time after giving such
     notification.

          (b) if there has been a material breach by Parent or Merger Sub of any
     representation, warranty, covenant or agreement contained in this Agreement
     that is not curable or, if curable, is not cured within 30 days after
     written notice of such breach is given by the Company to the party
     committing such breach.

     9.4.  Termination by Parent.  This Agreement may be terminated and the
Merger may be abandoned at any time prior to the Effective Time, whether before
or after the approval by the stockholders of Parent referred to in Section
8.1(a), by action of the Board of Directors of Parent if (i) the Board of
Directors of the Company shall have withdrawn or adversely modified its approval
or recommendation of this Agreement or failed to reconfirm its recommendation of
this Agreement within five business days after a written request by Parent to do
so, (ii) there has been a material breach by the Company of any representation,
warranty, covenant or agreement contained in this Agreement that is not curable
or, if curable, is not cured within 30 days after written notice of such breach
is given by Parent to the Company or (iii) if the Company or any of the other
Persons described in Section 7.2 as affiliates, representatives or agents of the
Company shall take any of the actions that would be proscribed by Section 7.2
but for the proviso therein allowing certain actions to be taken pursuant to
clause (i), (ii) or (iii) of the proviso under the conditions set forth therein.

     9.5.  Effect of Termination and Abandonment.  (a) In the event of
termination of this Agreement and the abandonment of the Merger pursuant to this
Article, this Agreement (other than the provisions of Sections 9.5, 11.4 and
11.5) shall become void and of no effect with no liability on the part of any
party hereto (or of any of its directors, officers, employees, agents, legal and
financial advisors or other representatives); provided, however, except as
otherwise provided herein, no such termination shall relieve any party hereto of
any liability or damages resulting from any breach of this Agreement.

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<PAGE>   126

     (b) In the event that this Agreement is terminated (x) by the Company
pursuant to Section 9.3(a) or (y) by Parent pursuant to Section 9.4(i) (in
connection with a Superior Proposal) or Section 9.4(iii), then the Company shall
promptly, but in no event later than two days after the date of such
termination, pay Parent a termination fee of $2,500,000 and shall promptly, but
in no event later than two days after being notified of such by Parent, pay all
of the charges and expenses, including those of the Exchange Agent, incurred by
Parent or Merger Sub in connection with the Transaction Agreements and the
transactions contemplated by the Transaction Agreements up to a maximum amount
of $1,000,000, in each case payable by wire transfer of same day funds. The
Company's payment shall be the sole and exclusive remedy of Parent and Merger
Sub against the Company and its directors, officers, employees, agents, advisors
or other representatives with respect to the breach of any covenant or agreement
giving rise to such payment; provided, however, no such payment shall relieve
any party hereto of any liability or damages resulting solely from any willful
breach of this Agreement. The Company acknowledges that the agreements contained
in this Section 9.5(b) are an integral part of the transactions contemplated by
this Agreement, and that, without these agreements, Parent and Merger Sub would
not enter into this Agreement; accordingly, if the Company fails to promptly pay
the amount due pursuant to this Section 9.5(b), and, in order to obtain such
payment, Parent or Merger Sub commences a suit which results in a judgment
against the Company for the fee set forth in this paragraph (b), the Company
shall pay to Parent or Merger Sub its costs and expenses (including attorneys'
fees) in connection with such suit, together with interest (at a 10% rate) on
the amount of the fee.

                                   ARTICLE X

                                INDEMNIFICATION

     10.1.  Survival; Right to Indemnification Not Affected by Knowledge;
Representations and Warranties Made as of the Closing Date.

     (a) All representations, warranties, covenants, and obligations in this
Agreement, the Disclosure Schedules and any other certificate or document
delivered pursuant to this Agreement shall survive for one year after the
Effective Time (the "Survival Date") other than the representation and warranty
contained in Section 6.2(g) which shall not survive the Effective Time. Each
party's indemnification obligations, or liability obligations pursuant to
Section 10.8, with respect to representations, warranties, covenants, and
obligations in this Agreement, the Disclosure Schedules and any other
certificate or document delivered pursuant to this Agreement shall terminate
when the applicable representation, warranty, covenant, obligation terminates
pursuant to this Section; provided, however, that such obligations to indemnify,
or liability obligations pursuant to Section 10.8, shall not terminate with
respect to a particular item as to which, before the expiration of the
applicable survival period, the party (i) seeking indemnification has made a
claim by delivering a notice of such claim (in accordance with the terms of this
Article) to the parties from which indemnification is sought or (ii) seeking
Damages in accordance with Section 10.8 has commenced legal proceedings.

     (b) Except as otherwise set forth in this Article X, the right to
indemnification, payment of Damages or other remedy based on such
representations, warranties, covenants and obligations shall not be affected by
any investigation conducted with respect to, or any knowledge acquired (or
capable of being acquired) at any time, whether before or after the execution
and delivery of this Agreement or the Closing Date, with respect to the accuracy
or inaccuracy of or compliance with, any such representation, warranty, covenant
or obligation. The waiver of any condition based on the accuracy of any
representation or warranty, or on the performance of or compliance with any
covenant or obligation, shall not affect the right to indemnification, payment
of Damages, or other remedy based on such representations, warranties,
covenants, and obligations.

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<PAGE>   127

     (c) Notwithstanding anything herein to the contrary, the representations
and warranties contained in Sections 6.1 and 6.2 of this Agreement shall, for
purposes of each party's indemnification obligations and liability obligations
pursuant to Section 10.8, be deemed to be made as of the date of this Agreement
and as of the Closing Date (except to the extent any such representation or
warranty expressly speaks of an earlier date) without regard to the exceptions
set forth in the certificates delivered in connection with Sections 8.2(a) and
8.3(a).

     10.2.  Indemnification and Payment of Damages by Holders of Shares.  The
holders of Shares shall jointly and severally indemnify and hold harmless Parent
and its Affiliates and each of their respective officers, directors, employees,
stockholders, agents and representatives (collectively, the "Parent Indemnified
Parties"), for, and shall pay to the Parent Indemnified Parties the amount of,
any loss, liability, claim, damage or expense (including costs of investigation
and defense and reasonable attorneys' fees), whether or not involving a
third-party claim (collectively, "Damages"), directly or indirectly arising or
resulting from or in connection with:

          (a) any breach of any representation or warranty made by the Company,
     the Stockholders of the Company set forth on the signature pages of this
     Agreement or the Stockholder Representative (on behalf of the stockholders
     of the Company) in this Agreement or in any certificate delivered by the
     Company pursuant to this Agreement;

          (b) any breach by the Company of any covenant or obligation of the
     Company in this Agreement; or

          (c) any breach of, or failure to assign to Parent or any Affiliate of
     Parent all of the rights under and terms of, any Contract to which the
     Company is a party directly or indirectly arising or resulting from or in
     connection with the Company's ceasing to exist by virtue of Merger.

     10.3.  Indemnification and Payment of Damages by Parent.  Parent shall
indemnify and hold harmless the holders of Shares, and shall pay to such holders
the amount of any Damages arising, directly or indirectly, from or in connection
with:

          (a) any breach of any representation or warranty made by Parent in
     this Agreement or in any certificate delivered by Parent pursuant to this
     Agreement; or

          (b) any breach by Parent of any covenant or obligation of Parent in
     this Agreement.

     10.4.  Limitations on Amount -- Holder of Shares.  Holders of Shares shall
not have liability for indemnification with respect to any matter described in
clause (a), (b) or (c) of Section 10.2 (i) unless and until the total amount of
all Damages with respect to such matters, taken together, exceeds $500,000, in
which case the applicable Parent Indemnified Party shall be entitled to
indemnification for the entire amount of the Parent Indemnified Party's Damages
and (ii) for any Damages in the aggregate in excess of the Holdback; provided,
however, that this Section 10.4 shall not apply to any breach of the Company's
representations and warranties of which the Company had knowledge at any time
prior to the date on which such representation and warranty is made or any
intentional breach by the Company of any covenant or obligation, and the holders
of Shares shall be liable for all Damages with respect to such breaches.

     10.5.  Limitations on Amount -- Parent.  Parent shall have no liability
(for indemnification or otherwise) with respect to the matters described in
clause (a) or (b) of Section 10.3 (i) unless and until the total of all Damages
with respect to such matters, taken together, exceeds $500,000, in which case
the holders of Shares shall be entitled to indemnification for the entire amount
of their Damages and (ii) for any Damages in the aggregate in excess of an
amount equal to (x) 535,000 multiplied by (y) the closing price on the NASDAQ of
the Parent Stock on the Closing Date; provided, however, that this Section 10.5
shall not apply to any breach of the Parent's representations and warranties of
which the Parent had knowledge at any time prior to the date on which such

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<PAGE>   128

representation and warranty is made or any intentional breach by Parent of any
covenant or obligation, and Parent shall be liable for all Damages with respect
to such breaches.

     10.6.  Payments to Parent.  (a) Any payment to be made to a Parent
Indemnified Party pursuant to this Article, shall be made in shares of Parent
Common Stock valued at the Closing price on the NASDAQ of the Parent Stock on
the Closing Date in accordance with the terms of the Escrow Agreement.

     (b) All shares of Parent Common Stock held in the Holdback Account (the
"Held Back Shares") shall, for federal income tax purposes, be deemed to be
owned by the stockholders of the Company, or such other persons or entities in
whose names the stockholders may instruct Parent to record on the stock transfer
books of the Company the Held Back Shares, who or which shall be entitled to
vote the Held Back Shares on all matters presented to the stockholders of
Parent. Except with respect to any reclassification, recapitalization, stock
split or combination, exchange or readjustment of shares in the event any
dividends or distributions are made on or in respect of the Held Back Shares,
such dividends or distributions received with respect to such Held Back Shares
from the Effective Time through the time of such payment shall be paid to the
stockholders of the Company in accordance with the terms of the Escrow
Agreement.

     10.7.  Procedures for Indemnification.  The party seeking indemnification
pursuant to this Article (the "Indemnified Party") agrees to give prompt notice
to the parties providing indemnification pursuant to this Article (the
"Indemnifying Parties") of the assertion of any claim, or the commencement of
any suit, action or proceeding in respect of which indemnity may be sought under
this Article; provided that the failure to give such notice shall not affect the
rights of the Indemnifying Party except to the extent the Indemnified Party is
materially prejudiced by such failure. The notice shall state the information
then available regarding the amount and nature of such claim, liability or
expense and shall specify the provision or provisions of this Agreement under
which the liability or obligation is asserted. The Indemnifying Party may at the
request of the Indemnified Party participate in and control the defense of any
such suit, action or proceeding at its own expense. If the Indemnifying Party
admits responsibility for indemnification with respect to such claim, the
Indemnifying Party shall be entitled to control the defense of any such suit,
action or proceeding at its own expense. The Indemnified Party shall cooperate
with the Indemnifying Party in such defense; provided that the Indemnified Party
shall not be obligated to incur any out-of-pocket expenses except to the extent
the Indemnifying Party agrees in writing to reimburse the Indemnified Party for
such expenses as they are incurred. The Indemnifying Party shall not be liable
for any settlement effected without its consent of any claim, litigation or
proceeding in respect of which indemnification may be sought hereunder; provided
that such consent shall not be unreasonably withheld (it being understood that
the Indemnifying Party may withhold consent if such settlement does not release
the Indemnifying Party from liability (in its capacity as Indemnifying Party) in
connection with such claim, litigation or proceeding). Without the consent of
the Indemnified Party, which consent shall not be unreasonably withheld, the
Indemnifying Party shall not settle any claim, litigation or proceeding in
respect of which indemnity may be sought hereunder if such settlement involves
an admission of liability or wrongdoing on the part of the Indemnified Party, or
a restriction on the operation of the Indemnified Party's business in the future
or would materially adversely affect the business reputation or Tax liability of
the Indemnified Party.

     10.8.  Non-Exclusive Remedy.  (a) Notwithstanding anything herein to the
contrary, the parties hereto acknowledge and agree that the provisions of this
Article X with respect to indemnification shall not be the exclusive remedy for
Parent and that Parent shall have the right to recover Damages from the holders
of Shares from any court of competent jurisdiction for, and that the holders of
Shares shall be jointly and severally liable for, Damages directly or indirectly
arising or resulting from or in connection with: (i) any breach of any
representation or warranty made by the Company, the

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<PAGE>   129

Stockholders Representative (on behalf of the stockholders of the Company) or
the stockholders of the Company set forth on the signature pages of this
Agreement or in any certificate delivered by the Company pursuant to this
Agreement; (ii) any breach by the Company of any covenant or obligation of the
Company in this Agreement or (iii) any breach of, or failure to assign to Parent
or any Affiliate of Parent of all of the terms of, any Contract to which the
Company is a party directly or indirectly arising or resulting from or in
connection with the Company's ceasing to exist by virtue of the Merger;
provided, however, the holders of Shares shall not have any liability for any
Damages in the aggregate in excess of the amount equal to (x) 535,000 multiplied
by (y) the closing price on the NASDAQ of the Parent Stock on the Closing Date.

     (b) Any payment of a Damage claim pursuant to Section 10.8 may, at the
option of the holder of Shares, be made in cash or in shares of Parent Common
Stock having a value equal to the amount of cash that would satisfy in full such
Damage claim.

     10.9.  Tax Treatment.  Indemnification payments made pursuant to this
Article shall be treated for Tax purposes as adjustments to the Merger
Consideration.

     10.10.  Pooling.  It is understood and agreed that no party to this
Agreement shall take any action or omit to take any action pursuant to this
Article to the extent that such action or omission would result in the Merger
not qualifying for pooling-of-interests accounting treatment under GAAP.

                                   ARTICLE XI

                           MISCELLANEOUS AND GENERAL

     11.1.  Modification or Amendment.  Subject to the provisions of the
applicable law, at any time prior to the Effective Time, the parties hereto may
modify or amend this Agreement, by written agreement executed and delivered by
duly authorized officers of the respective parties.

     11.2.  Waiver of Conditions.  At any time prior to the Effective Time, any
party hereto may (a) extend the time for the performance of any of the
obligations or other acts of any other party hereto or (b) waive compliance with
any of the agreements of any other party or any conditions to its own
obligations, in each case only to the extent such obligations, agreements and
conditions are intended for its benefit and to the extent permitted by
applicable law. Any such extension or waiver shall be binding upon a party only
if such extension or waiver is set forth in a writing executed by such party.

     11.3.  Counterparts.  This Agreement may be executed in any number of
counterparts, each such counterpart being deemed to be an original instrument,
and all such counterparts shall together constitute the same agreement.

     11.4.  GOVERNING LAW AND VENUE; WAIVER OF JURY TRIAL.  (a) THIS AGREEMENT
SHALL BE DEEMED TO BE MADE IN AND IN ALL RESPECTS SHALL BE INTERPRETED,
CONSTRUED AND GOVERNED BY AND IN ACCORDANCE WITH THE LAW OF THE STATE OF
DELAWARE WITHOUT REGARD TO THE CONFLICT OF LAW PRINCIPLES THEREOF. THE PARTIES
HEREBY IRREVOCABLY SUBMIT TO THE JURISDICTION OF THE COURTS OF THE STATE OF
DELAWARE AND THE FEDERAL COURTS OF THE UNITED STATES OF AMERICA LOCATED IN THE
STATE OF DELAWARE SOLELY IN RESPECT OF THE INTERPRETATION AND ENFORCEMENT OF THE
PROVISIONS OF THE TRANSACTION AGREEMENTS, AND IN RESPECT OF THE TRANSACTIONS
CONTEMPLATED THEREBY, AND HEREBY WAIVE, AND AGREE NOT TO ASSERT, AS A DEFENSE IN
ANY ACTION, SUIT OR PROCEEDING FOR THE INTERPRETATION OR ENFORCEMENT HEREOF OR
OF ANY SUCH DOCUMENT, THAT IT IS NOT SUBJECT THERETO OR THAT SUCH ACTION, SUIT
OR

                                      A-40
<PAGE>   130

PROCEEDING MAY NOT BE BROUGHT OR IS NOT MAINTAINABLE IN SAID COURTS OR THAT THE
VENUE THEREOF MAY NOT BE APPROPRIATE OR THAT ANY OF THE TRANSACTION AGREEMENTS
MAY NOT BE ENFORCED IN OR BY SUCH COURTS, AND THE PARTIES HERETO IRREVOCABLY
AGREE THAT ALL CLAIMS WITH RESPECT TO SUCH ACTION OR PROCEEDING SHALL BE HEARD
AND DETERMINED IN SUCH A DELAWARE STATE OR FEDERAL COURT. THE PARTIES HEREBY
CONSENT TO AND GRANT ANY SUCH COURT JURISDICTION OVER THE PERSON OF SUCH PARTIES
AND OVER THE SUBJECT MATTER OF SUCH DISPUTE AND AGREE THAT MAILING OF PROCESS OR
OTHER PAPERS IN CONNECTION WITH ANY SUCH ACTION OR PROCEEDING IN THE MANNER
PROVIDED IN SECTION 11.5 OR IN SUCH OTHER MANNER AS MAY BE PERMITTED BY LAW
SHALL BE VALID AND SUFFICIENT SERVICE THEREOF.

     (b) EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH MAY ARISE
UNDER THE TRANSACTION AGREEMENTS IS LIKELY TO INVOLVE COMPLICATED AND DIFFICULT
ISSUES, AND THEREFORE EACH SUCH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY
WAIVES ANY RIGHT SUCH PARTY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY
LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO ANY OF THE
TRANSACTION AGREEMENTS, OR THE TRANSACTIONS CONTEMPLATED THEREBY. EACH PARTY
CERTIFIES AND ACKNOWLEDGES THAT (i) NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY
OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD
NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER, (ii) EACH
PARTY UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THIS WAIVER, (iii) EACH
PARTY MAKES THIS WAIVER VOLUNTARILY, AND (iv) EACH PARTY HAS BEEN INDUCED TO
ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION 11.4.

     11.5.  Notices.  Any notice, request, instruction or other document to be
given hereunder by any party to the others shall be in writing and delivered
personally or sent by express mail or equivalent over-night courier service,
prepaid, or by facsimile:

         if to Parent or Merger Sub

         Affymetrix, Inc.
         3380 Central Expressway
         Santa Clara, CA 95051
         Attention: General Counsel (Vern Norviel)
         fax: (408) 481-4709

         (with a copy to Neil Anderson, Esq.
         Sullivan & Cromwell
         125 Broad Street, New York, NY 10004
         fax: (212) 558-3588).

         if to the Company

         Genetic MicroSystems, Inc.
         34 Commerce Way
         Woburn, MA 01801
         Attention: Jean Montagu
         fax: (781) 932-9433

                                      A-41
<PAGE>   131

         (with a copy to Michael Lytton, Esq.
         Palmer & Dodge, LLP
         One Beacon Street
         Boston, MA 02108
         fax: (617) 227-4420)

or to such other persons or addresses as may be designated in writing by the
party to receive such notice as provided above.

     11.6.  Entire Agreement.  This Agreement (including any exhibits hereto),
the Company Disclosure Schedule, the Parent Disclosure Schedule, the Stock
Option Agreement and the Escrow Agreement constitute the entire agreement, and
supersede all other prior agreements, understandings, representations and
warranties both written and oral, among the parties, with respect to the subject
matter hereof.

     11.7.  No Third Party Beneficiaries.  This Agreement is not intended to
confer upon any Person other than the parties hereto any rights or remedies
hereunder.

     11.8.  Obligations of Parent.  Whenever this Agreement requires Merger Sub
to take any action, such requirement shall be deemed to include an undertaking
on the part of Parent to cause Merger Sub to take such action.

     11.9.  Transfer Taxes.  All transfer, documentary, sales, use, stamp,
registration and other such Taxes and fees (including penalties and interest)
incurred by Parent or the Company in connection with the Merger shall be paid
50% by Parent and 50% by the Company when due.

     11.10.  Severability.  The provisions of this Agreement shall be deemed
severable and the invalidity or unenforceability of any provision shall not
affect the validity or enforceability or the other provisions hereof. If any
provision of this Agreement, or the application thereof to any Person or any
circumstance, is invalid or unenforceable, (a) a suitable and equitable
provision shall be substituted therefor in order to carry out, so far as may be
valid and enforceable, the intent and purpose of such invalid or unenforceable
provision and (b) the remainder of this Agreement and the application of such
provision to other Persons or circumstances shall not be affected by such
invalidity or unenforceability, nor shall such invalidity or unenforceability
affect the validity or enforceability of such provision, or the application
thereof, in any other jurisdiction.

     11.11.  Interpretation.  (a) The table of contents and headings herein are
for convenience of reference only, do not constitute part of this Agreement and
shall not be deemed to limit or otherwise affect any of the provisions hereof.
Where a reference in this Agreement is made to a Section or Exhibit, such
reference shall be to a Section of or Exhibit to this Agreement unless otherwise
indicated. Whenever the words "include," "includes" or "including" are used in
this Agreement, they shall be deemed to be followed by the words "without
limitation."

     (b) The inclusion of any matter in a Section or Schedule to the Company
Disclosure Schedule shall also be deemed to be an inclusion for any other
Section or Schedule in the Company Disclosure Schedule if there is a sufficient
indication in the Section or Schedule containing the inclusion to reasonably
inform a Person of the applicability of the matter to such other Schedule. In
the event of any conflict between the Parent Disclosure Schedule or the Company
Disclosure Schedule and this Agreement, the terms of this Agreement shall
prevail.

     11.12.  Assignment.  This Agreement shall not be assignable by operation of
law or otherwise; provided, however, (i) Parent may assign this Agreement to any
entity that acquires substantially all of the business or assets of Parent and
(ii) that Parent may designate, by written notice to the Company, another
wholly-owned direct or indirect Subsidiary to be a Constituent Corporation in
lieu of Merger Sub, in which event all references herein to Merger Sub shall be
deemed references to
                                      A-42
<PAGE>   132

such other Subsidiary, except that all representations and warranties made
herein with respect to Merger Sub as of the date of this Agreement shall be
deemed representations and warranties made with respect to such other Subsidiary
as of the date of such designation.

     11.13.  Specific Performance.  The parties hereto acknowledge that, in view
of the uniqueness of the subject matter hereof, the parties hereto would not
have an adequate remedy at law for money damages if this Agreement were not
performed in accordance with its terms, and therefore agree that the parties
hereto shall be entitled to specific enforcement of the terms hereof in addition
to any other remedy to which the parties hereto may be entitled at law or in
equity.

     IN WITNESS WHEREOF, this Agreement has been duly executed and delivered by
the duly authorized officers of the parties hereto as of the date first written
above.

                                          AFFYMETRIX, INC.

                                          By: /s/ VERN NORVIEL
                                            ------------------------------------
                                              Name: Vern Norviel
                                              Title: Vice President, General
                                                     Counsel and Corporate
                                                     Secretary

                                          GMS ACQUISITION, INC.

                                          By: /s/ SUSAN E. SIEGEL
                                            ------------------------------------
                                              Name: Susan E. Siegel
                                              Title: President

                                          By: /s/ EDWARD HURWITZ
                                            ------------------------------------
                                              Name: Edward Hurwitz
                                              Title: Treasurer

                                          GENETIC MICROSYSTEMS, INC.

                                          By: /s/ JEAN MONTAGU
                                            ------------------------------------
                                              Name: Jean Montegu
                                              Title: President

                                          By: /s/ PETER LEWIS
                                            ------------------------------------
                                              Name: Peter Lewis
                                              Title: Treasurer

                                      A-43
<PAGE>   133

                                          Stockholder Representative
                                          (on behalf of all of the stockholders
                                          of Genetic MicroSystems, Inc.)

                                          By: /s/ JEAN MONTAGU
                                            ------------------------------------
                                              Name: Jean Montagu

                                              /s/ STANLEY ROSE
                                            ------------------------------------
                                              Stanley Rose

                                              /s/ PETER HONKANEN
                                            ------------------------------------
                                              Peter Honkanen

                                              /s/ MYLES L. MACE, JR.
                                            ------------------------------------
                                              Myles L. Mace, Jr.

                                              /s/ DOMINIC MONTAGU
                                            ------------------------------------
                                              Dominic Montagu

                                              /s/ SASHA MONTAGU
                                            ------------------------------------
                                              Sasha Montagu

                                      A-44
<PAGE>   134

                                                                      APPENDIX B

                             STOCK OPTION AGREEMENT

     STOCK OPTION AGREEMENT, dated as of September 10, 1999 (the "Agreement"),
between Affymetrix, Inc., a Delaware corporation (the "Grantee"), and Genetic
MicroSystems, Inc., a Massachusetts corporation (the "Grantor").

     WHEREAS, the Grantee, GMS Acquisition, Inc., a Massachusetts corporation
and a wholly owned subsidiary of the Grantee ("Merger Sub"), the Grantor and
Jean Montagu as Stockholder Representative are entering into an Agreement and
Plan of Merger, dated as of the date hereof (the "Merger Agreement"), which
provides, among other things, for the merger of Merger Sub with and into Grantor
(the "Merger");

     WHEREAS, the Grantee and Merger Sub have requested that the Grantor grant
to the Grantee an option to purchase up to 684,297 shares of Common Stock, no
par value per share, of the Grantor (the "Common Stock"), on the terms and
subject to the conditions hereof; and

     WHEREAS, the Grantor is willing to grant the Grantee the requested option.

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
and agreements set forth herein, the parties hereto agree as follows:

     1.  The Option; Exercise; Adjustments; Payment of Spread; Repurchase Right.

     (a) Contemporaneously herewith the Grantee, Merger Sub and the Grantor are
entering into the Merger Agreement. Subject to the other terms and conditions
set forth herein, the Grantor hereby grants to the Grantee an irrevocable option
(the "Option") to purchase up to 684,297 shares of Common Stock (the "Shares")
at a cash purchase price equal to $21.50 per share (the "Purchase Price"). The
Option may be exercised by the Grantee, in whole or in part, at any time, or
from time to time, following (but not prior to) the occurrence of the events set
forth in any of clauses (i), (ii), (iii) or (iv) of Section 2(d) hereof, and
prior to the Termination Date (as defined herein).

     (b) In the event the Grantee wishes to exercise the Option, the Grantee
shall send a written notice to the Grantor (the "Stock Exercise Notice")
specifying the total number of Shares it wishes to purchase and a date (subject
to the expiration or termination of any applicable waiting period under the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the "HSR
Act")) not later than 10 business days and not earlier than three business days
following the date such notice is given for the closing of such purchase. In the
event of any change in the number of issued and outstanding shares of capital
stock of the Company (by reason of any stock dividend, stock split, split-up,
recapitalization, merger, issuance of capital stock upon exercise of warrants or
options or any other event), the number of Shares subject to this Option and the
purchase price per Share shall be appropriately adjusted to restore the Grantee
to its rights hereunder.

     (c) If at any time the Option is then exercisable pursuant to the terms of
Section 1(a) hereof and at or prior to such time the termination fee referred to
in Section 9.5(b) of the Merger Agreement shall have become payable, the Grantee
may from time to time elect, in lieu of exercising the Option to purchase Shares
provided in Section 1(a) hereof, to send a written notice to the Grantor (a
"Cash Exercise Notice") specifying a date not later than 20 business days and
not earlier than 10 business days following the date such notice is given on
which date the Grantor shall pay to the Grantee an amount in cash (the
"Cancellation Amount") equal to the Spread (as hereinafter defined) multiplied
by all or such portion of the Shares subject to the Option as Grantee shall
specify. As used herein "Spread" shall mean the excess over the Purchase Price
of the highest price per share of Common Stock (including any brokerage
commissions, transfer taxes and soliciting dealers' fees) paid or proposed to be
paid by any person pursuant to any Acquisition Proposal (as

                                       B-1
<PAGE>   135

defined in the Merger Agreement) occurring after the date of this Agreement and
prior to the Termination Date (the "Alternative Purchase Price"). If the
Alternative Purchase Price includes any property other than cash, the
Alternative Purchase Price shall be the sum of (i) the fixed cash amount, if
any, included in the Alternative Purchase Price plus (ii) the fair market value
of such other property. If such other property consists of securities with an
existing public trading market, the average of the closing prices (or the
average of the closing bid and asked prices if closing prices are unavailable)
for such securities in their principal public trading market on the five trading
days ending five days prior to the date of the Cash Exercise Notice shall be
deemed to equal the fair market value of such property. Upon exercise of its
right to receive cash pursuant to this Section 1(c), the obligations of the
Grantor to deliver Shares pursuant to Section 3 shall be terminated with respect
to such number of Shares for which the Grantee shall have elected to be paid the
Spread.

     (d) At the request of the Grantor at any time during the 180-day period
commencing on each date on which the Option is exercised (the "Call Period"),
the Grantor may repurchase from the Grantee, and the Grantee shall sell to the
Grantor, any or all of the Shares acquired by the Grantee pursuant hereto as a
result of such exercise and with respect to which the Grantee has beneficial
ownership at the time of such repurchase at a price per share equal to the
Repurchase Price (defined below) per share in respect of the Shares so acquired
(such price per share multiplied by the number of Shares to be repurchased
pursuant to this Section 1(d) being herein called the "Repurchase
Consideration"). Each date on which the Grantor exercises its rights under this
Section 1(d) by delivering its request to the Grantee is referred to as a
"Grantor Request Date." "Repurchase Price" per share shall be the Purchase
Price. If the Grantor exercises its rights under this Section 1(d), the Grantor
shall, within five business days after the applicable Grantor Request Date, pay
the applicable Repurchase Consideration in immediately available funds, and the
Grantee shall surrender to the Grantor certificates evidencing the Shares
purchased hereunder, and the Grantee shall warrant to the Grantor that,
immediately prior to the repurchase thereof pursuant to this Section 1(d), the
Grantee had sole record and beneficial ownership of such Shares and that such
Shares were then held free and clear of all encumbrances.

     2.  Conditions to Delivery of Shares.  The Grantor's obligation to deliver
Shares upon exercise of the Option is subject only to the conditions that:

          (a) No preliminary or permanent injunction or other order issued by
     any federal or state court of competent jurisdiction prohibiting the
     delivery of the Shares shall be in effect; and

          (b) Any applicable waiting periods under the HSR Act shall have
     expired or been terminated; and

          (c) the representations and warranties of the Grantee made in Section
     5 of this Agreement shall be true and correct in all material respects as
     of the date of the closing of the issuance of the Shares; and

          (d) (i) in the event that (A) a bona fide Acquisition Proposal (as
     defined in the Merger Agreement) shall have been made to the Grantor or any
     of its stockholders, and on or following the date of the Merger Agreement,
     but prior to the date of the meeting of the Grantor's stockholders to
     approve the Merger Agreement, such Acquisition Proposal is or becomes
     publicly known, and (B) on or following the date on which such Acquisition
     Proposal is or becomes publicly known, (i) the Merger Agreement is
     terminated by the Grantor pursuant to Section 9.3(a) of the Merger
     Agreement or (ii) the Merger Agreement is terminated by the Grantee
     pursuant to clause (i) (in connection with a Superior Proposal) or clause
     (iii) of Section 9.4 of the Merger Agreement; or (iii) the Grantor shall
     have delivered to Grantee the written notification pursuant to Section
     9.3(a)(ii) of the Merger Agreement and the Grantee

                                       B-2
<PAGE>   136

     shall have notified the Grantor in writing that the Grantee does not intend
     to match the Superior Proposal (as defined in the Merger Agreement)
     referred to in such notification. As used in this Agreement, "person" shall
     have the meaning specified in Sections 3(a)(9) and 13(d)(3) of the
     Securities Exchange Act of 1934, as amended.

3.  The Closing.

     (a) Any closing hereunder shall take place on the date specified by the
Grantee in its Stock Exercise Notice or Cash Exercise Notice or as specified in
Section 1(d), as the case may be, at 10:00 A.M., local time, at the offices of
Sullivan & Cromwell, 125 Broad Street, New York, New York, or, if the conditions
set forth in Section 2(a), (b) or (c) have not then been satisfied, on the
second business day following the satisfaction of such conditions, or at such
other time and place as the parties hereto may agree (the "Closing Date"). On
the Closing Date, (i) in the event of a closing pursuant to Section 1(b) hereof,
the Grantor will deliver to the Grantee a certificate or certificates,
representing the Shares in the denominations designated by the Grantee in its
Stock Exercise Notice and the Grantee will purchase such Shares from the Grantor
at the price per Share equal to the Purchase Price, (ii) in the event of a
closing pursuant to Section 1(c) hereof, the Grantor will deliver to the Grantee
cash in an amount determined pursuant to Section 1(c) hereof; or (iii) in the
event of a closing pursuant to Section 1(d) hereof, the Grantor will deliver to
the Grantee cash in an amount determined pursuant to Section 1(d) hereof. Any
payment made by the Grantee to the Grantor, or by the Grantor to the Grantee,
pursuant to this Agreement shall be made by certified or official bank check or
by wire transfer of federal funds to a bank designated by the party receiving
such funds.

     (b) The Grantee agrees not to transfer or otherwise dispose of the Option
or the Shares, or any interest therein, except in compliance with the Securities
Act of 1933, as amended (the "Securities Act") and any applicable state
securities law. The Grantee further agrees that the certificates representing
the Shares shall bear an appropriate legend relating to the fact that such
Shares have not been registered under the Securities Act.

     4.  Representations and Warranties of the Grantor.  The Grantor represents
and warrants to the Grantee that (a) the Grantor is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Massachusetts and has the requisite corporate power and authority to enter into
and perform this Agreement; (b) the execution and delivery of this Agreement by
the Grantor and the consummation by it of the transactions contemplated hereby
have been duly authorized by the Board of Directors of the Grantor and this
Agreement has been duly executed and delivered by a duly authorized officer of
the Grantor and constitutes a valid and binding obligation of the Grantor,
enforceable in accordance with its terms; (c) the Grantor has taken all
necessary corporate action to authorize and reserve the Shares issuable upon
exercise of the Option and the Shares, when issued and delivered by the Grantor
upon exercise of the Option and paid for by the Grantee as contemplated hereby,
will be duly authorized, validly issued, fully paid and non-assessable and free
of preemptive rights; (d) except as otherwise required by the HSR Act, the
execution and delivery of this Agreement by the Grantor and the consummation by
it of the transactions contemplated hereby do not require the consent, waiver,
approval or authorization of or any filing with any person or public authority
and will not violate, result in a breach of or the acceleration of any
obligation under, or constitute a default under, any provision of the Grantor's
Organizational Documents (as defined in the Merger Agreement), or any indenture,
mortgage, lien, lease, agreement, contract, instrument, order, rule, regulation,
judgment, ordinance, or decree, or restriction by which the Grantor or any of
its subsidiaries or any of their respective properties or assets is bound; and
(e) no "fair price", "moratorium", "control share acquisition," "interested
shareholder" or other form of antitakeover statute or regulation (including but
not limited to Chapters 110C, 110D, 110E

                                       B-3
<PAGE>   137

and 110F of the General Laws of the Commonwealth of Massachusetts) is or shall
be applicable to the acquisition of Shares pursuant to this Agreement.

     5.  Representations and Warranties of the Grantee.  The Grantee represents
and warrants to the Grantor that (a) the Grantee is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has the requisite corporate power and authority to enter into and
perform this Agreement, (b) the execution and delivery of this Agreement by the
Grantee and the consummation by it of the transactions contemplated hereby have
been duly authorized by all necessary corporate action on the part of the
Grantee and this Agreement has been duly executed and delivered by a duly
authorized officer of the Grantee and constitutes a valid and binding obligation
of the Grantee, enforceable in accordance with its terms; and (c) the Grantee is
acquiring the Option and, if and when it exercises the Option, will be acquiring
the Shares issuable upon the exercise thereof for its own account and not with a
view to distribution or resale in any manner which would be in violation of the
Securities Act.

     6.  Filings; Governmental Consents.  After the Option becomes exercisable
hereunder, the Grantor will use its reasonable best efforts to obtain approval
of such listing and to effect all necessary filings by the Grantor under the HSR
Act. Each of the parties hereto will use its reasonable best efforts to obtain
consents of all third parties and governmental authorities, if any, necessary to
the consummation of the transactions contemplated by this Agreement.

     7.  Expenses.  Each party hereto shall pay its own expenses incurred in
connection with this Agreement, except as otherwise specifically provided
herein.

     8.  Modification or Amendment.  Subject to the provisions of applicable
law, the parties hereto may modify or amend this Agreement, by written agreement
executed and delivered by duly authorized officers of the respective parties.

     9.  Counterparts.  This Agreement may be executed in any number of
counterparts, each such counterpart being deemed to be an original instrument,
and all such counterparts shall together constitute the same agreement.

     10.  GOVERNING LAW AND VENUE; WAIVER OF JURY TRIAL.

     (A) THIS AGREEMENT SHALL BE DEEMED TO BE MADE IN AND IN ALL RESPECTS SHALL
BE INTERPRETED, CONSTRUED AND GOVERNED BY AND IN ACCORDANCE WITH THE LAWS OF THE
STATE OF DELAWARE WITHOUT REGARD TO THE CONFLICT OF LAW PRINCIPLES THEREOF. The
parties hereby irrevocably submit to the jurisdiction of the courts of the State
of Delaware and the Federal courts of the United States of America located in
Delaware solely in respect of the interpretation and enforcement of the
provisions of this Agreement, the Merger Agreement and of the other documents
referred to in this Agreement and the Merger Agreement, and in respect of the
transactions contemplated hereby and thereby, and hereby waive, and agree not to
assert, as a defense in any action, suit or proceeding for the interpretation or
enforcement hereof or of any such document, that it is not subject thereto or
that such action, suit or proceeding may not be brought or is not maintainable
in said courts or that the venue thereof may not be appropriate or that this
Agreement, the Merger Agreement, or any such document may not be enforced in or
by such courts, and the parties hereto irrevocably agree that all claims with
respect to such action or proceeding shall be heard and determined in such a
Delaware State or Federal court. The parties hereby consent to and grant any
such court jurisdiction over the person of such parties and over the subject
matter of such dispute and agree that mailing of process or other papers in
connection with any such action or proceeding in the manner provided in Section
11 or in such other manner as may be permitted by law, shall be valid and
sufficient service thereof.

                                       B-4
<PAGE>   138

     (B) EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH MAY ARISE
UNDER THIS AGREEMENT IS LIKELY TO INVOLVE COMPLICATED AND DIFFICULT ISSUES, AND
THEREFORE EACH SUCH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY
RIGHT SUCH PARTY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION
DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE
TRANSACTIONS CONTEMPLATED HEREBY. EACH PARTY CERTIFIES AND ACKNOWLEDGES THAT (I)
NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED,
EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF
LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER, (II) EACH SUCH PARTY
UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THIS WAIVER, (III) EACH SUCH
PARTY MAKES THIS WAIVER VOLUNTARILY, AND (IV) EACH SUCH PARTY HAS BEEN INDUCED
TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION 10.

     11.  Notices.  Any notice, request, instruction or other document to be
given hereunder by any party to the others shall be in writing and delivered
personally or sent by registered or certified mail, postage prepaid, or by
facsimile:

        if to the Grantee:

          General Counsel: Vern Norviel
          Affymetrix, Inc.
          3380 Central Expressway
          Santa Clara, CA 95051
          fax: (408) 481-4709

        with copies to:

          Neil T. Anderson
          Sullivan & Cromwell
          125 Broad Street
          New York, NY 10004
          fax: (212) 558-3588

        if to the Grantor:

          Jean Montagu
          Genetic MicroSystems, Inc.
          34 Commerce Way
          Woburn, MA 01801
          fax: (781) 932-9433

        with copies to:

          Michael E. Lytton
          Palmer & Dodge LLP
          One Beacon Street
          Boston, MA 02108
          fax: (617) 227-4420

or to such other persons or addresses as may be designated in writing by the
party to receive such notice as provided above.

                                       B-5
<PAGE>   139

     12.  Entire Agreement.  This Agreement (including any exhibits and
schedules hereto), the Merger Agreement and the other documents referred to in
this Agreement and the Merger Agreement, constitute the entire agreement, and
supersede all other prior agreements, understandings, representations and
warranties both written and oral, among the parties, with respect to the subject
matter hereof.

     13.  No Third Party Beneficiaries.  This Agreement is not intended to
confer upon any person or entity other than the parties hereto any rights or
remedies hereunder.

     14.  Severability.  The provisions of this Agreement shall be deemed
severable and the invalidity or unenforceability of any provision shall not
affect the validity or enforceability of the other provisions hereof. If any
provision of this Agreement, or the application thereof to any person or entity
or any circumstance, is invalid or unenforceable, (a) a suitable and equitable
provision shall be substituted therefor in order to carry out, so far as may be
valid and enforceable, the intent and purpose of such invalid or unenforceable
provision and (b) the remainder of this Agreement and the application of such
provision to other persons or entities or circumstances shall not be affected by
such invalidity or unenforceability, nor shall such invalidity or
unenforceability affect the validity or enforceability of such provision, or the
application thereof, in any other jurisdiction.

     15.  Specific Performance.  The parties hereto each acknowledge that, in
view of the uniqueness of the subject matter hereof, the parties hereto would
not have an adequate remedy at law for money damages if this Agreement were not
performed in accordance with its terms, and therefore agree that the parties
hereto shall be entitled to specific enforcement of the terms hereof in addition
to any other remedy to which the parties hereto may be entitled at law or in
equity.

     16.  Assignment.  This Agreement shall not be assignable by operation of
law or otherwise; provided, however, that (i) the Grantee may assign this
Agreement to any entity that acquires substantially all of the business or
assets of the Grantee and (ii) the Grantee may assign its rights and obligations
under this Agreement to any of its direct or indirect wholly owned subsidiaries
(including Merger Sub). Any purported assignment made in contravention of this
Agreement shall be null and void.

     17.  Captions.  The Section captions herein are for convenience of
reference only and do not constitute part of this Agreement and shall not be
deemed to limit or otherwise affect any of the provisions hereof.

     18.  Termination.

     (a) The right to exercise the Option granted pursuant to this Agreement
shall terminate at (and the Option shall no longer be exercisable after) the
earliest of (i) the Effective Time (as defined in the Merger Agreement), (ii)
the first anniversary of the earliest to occur of the events set forth in any of
clauses (i), (ii), (iii) or (iv) of Section 2(d), and (iii) the thirtieth day
following the termination of the Merger Agreement if prior to such thirtieth day
the events set forth in any of clauses (i), (ii), (iii) or (iv) of Section 2(d)
shall not have occurred (such earliest date being referred to in this Agreement
as the "Termination Date"); provided that, if the Option cannot be exercised or
the Shares cannot be delivered to the Grantee upon such exercise because one or
more of the conditions set forth in Section 2(a) or (b) hereof have not yet been
satisfied, the Termination Date shall be extended until thirty days after such
impediment to exercise or delivery has been removed.

     (b) All representations and warranties contained in this Agreement shall
survive delivery of and payment for the Shares.

                                       B-6
<PAGE>   140

     19.  Profit Limitation.

     (a) Notwithstanding any other provision of this Agreement or the Merger
Agreement, in no event shall the Grantee's Total Profit (as hereinafter defined)
exceed $5,000,000 and, if it otherwise would exceed such amount, the Grantee
shall repay such excess amount to Grantor in cash so that Grantee's Total Profit
shall not exceed $5,000,000 after taking into account the foregoing actions.

     (b) As used herein, the term "Total Profit" shall mean the aggregate amount
(before taxes) of (i) the amount of cash actually received by Grantee pursuant
to Section 9.5 of the Merger Agreement and Section 1(c) hereof, less (ii) any
repayment of a portion of such cash to Grantor.

     IN WITNESS WHEREOF, this Agreement has been duly executed and delivered by
duly authorized officers of the parties hereto as of the date hereof.

                                          GENETIC MICROSYSTEMS, INC.

                                          By: /s/ JEAN MONTAGU
                                            ------------------------------------
                                              Name: Jean Montagu
                                              Title: President

                                          AFFYMETRIX, INC.

                                          By: /s/ VERN NORVIEL
                                            ------------------------------------
                                              Name: Vern Norviel
                                              Title: Vice President, General
                                                     Counsel, and Corporate
                                                     Secretary

                                       B-7
<PAGE>   141

                                                                      APPENDIX C

                                ESCROW AGREEMENT

     ESCROW AGREEMENT (hereinafter called this "Agreement"), dated as of
September 10, 1999, among Genetic MicroSystems, Inc., a Massachusetts
corporation (the "Company"), Affymetrix, Inc., a Delaware corporation
("Parent"), GMS Acquisition, Inc., a Massachusetts corporation and a
wholly-owned subsidiary of Parent ("Merger Sub"), Jean Montagu (the "Stockholder
Representative") and Bank One Trust Company, NA, as the Escrow Agent (the
"Escrow Agent").

     WHEREAS, Parent, Merger Sub, the Company, the Stockholder Representative
and certain stockholders of the Company have entered into an Agreement and Plan
of Merger dated as of September 10, 1999 (the "Merger Agreement") pursuant to
which, among other things, the Company shall merge with and into Merger Sub (the
"Merger");

     WHEREAS, pursuant to the terms of the Merger Agreement, Parent Indemnified
Parties (as defined below) are to be indemnified by the Company's stockholders
for certain events or occurrences specified in Article X of the Merger
Agreement, including breaches of representations, warranties, covenants and
agreements made, entered into or to be performed pursuant to the terms of the
Merger Agreement;

     NOW THEREFORE, in consideration of mutual promises and good and valuable
consideration, the receipt and sufficiency of which is hereby acknowledged, and
intending to be legally bound, the parties hereto agree as follows:

     1.  Definitions.  The following terms, as used herein, have the following
meaning:

          "business day" means any day other than a Saturday, a Sunday or a day
     on which banks in California are authorized or obligated by law or
     executive order to close.

          "Closing Date" means the date on which the Merger becomes effective.

          "Escrow Account" means a separate account established by the Escrow
     Agent for the purpose of holding shares of Parent Stock delivered to it
     pursuant to Section 3 (collectively, the "Assets").

          "Officer's Certificate" means a certificate signed by the President or
     any Vice-President of Parent substantially in the form attached hereto as
     Exhibit A stating that a Parent Indemnified Party has incurred or suffered
     any damages, losses, liabilities and expenses (including reasonable
     attorney fees and expenses) as a result of certain events or occurrences
     specified in Article X of the Merger Agreement, including a breach of any
     representation, warranty, covenant or agreement set forth in the Merger
     Agreement, for which indemnification is available pursuant to the Merger
     Agreement in the aggregate amount set forth in such Officer's Certificate
     (the "Indemnity Amount") that is delivered by Parent on the same day to the
     Escrow Agent and the Stockholder Representative.

          "Parent Indemnified Party" means Parent and any of its affiliates,
     including, effective upon the closing of the Merger, the Surviving
     Corporation.

          "Parent Stock" means the common stock, par value $0.01 per share, of
     Parent.

          "Person" means an individual, corporation, partnership, limited
     liability company, association, trust or other entity or organization,
     including a government or political subdivision or an agency or
     instrumentality thereof.

          "Subsidiary" means, with respect to any Person, any entity of which
     securities or other ownership interests having ordinary voting power to
     elect a majority of the board of directors or

                                       C-1
<PAGE>   142

     other persons performing similar functions are at any time directly or
     indirectly owned by such Person.

     2.  Appointment of the Escrow Agent.  Parent, Merger Sub, the Company and
the Stockholder Representative hereby appoint Bank One Trust Company, NA to act
as the Escrow Agent on the terms and conditions set forth herein and Bank One
Trust Company, NA hereby accepts such appointment on such terms and conditions.

     3.  Deposit of Shares.  In accordance with the Merger Agreement, Parent
shall deposit with the Escrow Agent at the closing of the Merger 107,000 shares
of Parent Stock.

     4.  Escrow Account.  The Escrow Agent shall deposit such shares, upon
receipt, into the Escrow Account and shall hold, safeguard and distribute such
shares in accordance with and subject to the terms of this Agreement. The shares
of Parent Stock held in the Escrow Account (i) shall not, so long as the Escrow
Account is in existence, be sold by the Stockholder Representative, any record
holder thereof or the Escrow Agent and (ii) shall be recorded on the stock
transfer books of Parent as being held in the name of the stockholder(s) who own
such shares of record and the Stockholder Representative shall execute any
assignment on behalf of such holders that is reasonably requested by the Escrow
Agent to permit the Escrow Agent to perform its duties hereunder. The Escrow
Agent shall exercise the voting rights associated with shares of Parent Stock
remaining in the Escrow Account in accordance with such instructions as the
Stockholder Representative may from time to time deliver to the Escrow Agent.

     5.  Purpose.  It is understood and agreed that the Escrow Account and the
Assets are for the purpose of satisfying the indemnification obligations owed to
Parent by the Stockholder Representative and the other stockholders of the
Company and no Assets shall be used for any other purpose except as explicitly
set forth in this Agreement.

     6.  Distributions on Parent Stock.  Parent shall pay to the Escrow Agent
all cash or stock dividends and other distributions (including by reason of any
reclassification, recapitalization, stock split or combination, exchange or
readjustment of shares) with respect to shares of Parent Stock held in the
Escrow Account. The Escrow Agent shall (i) deposit dividends and distributions
declared by reason of any reclassification, recapitalization, stock split or
combination, exchange or readjustment of shares of Parent Stock into the Escrow
Account in accordance with and subject to the terms of this Agreement and such
dividends and distributions will be held and distributed in accordance with the
terms of this Agreement and (ii) distribute cash or stock dividends and
distributions not declared by reason of any reclassification, recapitalization,
stock split or combination, exchange or readjustment of shares of Parent Stock
to the Stockholder Representative for distribution to the stockholders of the
Company in accordance with the relative ownership percentage of each such
stockholder.

     7.  Rights to the Escrow Account.  In accordance with and subject to the
terms of this Agreement, Parent Indemnified Parties shall be entitled to recover
from the Escrow Account the Indemnity Amount or the Final Indemnity Amount (as
defined below), as the case may be.

     8.  Indemnity Payments by the Escrow Agent.  (a) Subject to Section 8(b),
on the fifteenth business day after receipt by the Escrow Agent of an Officer's
Certificate, the Escrow Agent shall deliver to Parent from the Assets in a
manner specified in writing by Parent the number of shares of Parent Stock equal
to the quotient obtained by dividing the Indemnity Amount by the closing price
on the NASDAQ stock market of the Parent Stock on the Closing Date.

     (b) If the Stockholder Representative shall, within fifteen business days
after the Escrow Agent's and the Stockholder Representative's receipt of the
Officer's Certificate, notify the Escrow Agent and Parent in writing that the
Stockholder Representative objects to the Indemnity Amount, (i) the Indemnity
Amount shall not be delivered to Parent, (ii) Parent and the Stockholder

                                       C-2
<PAGE>   143

Representative shall (A) endeavor in good faith to agree on the amount the
Parent Indemnified Party shall be entitled to recover from the Escrow Account or
have such amount determined by a court of competent jurisdiction pursuant to the
Merger Agreement (such amount being the "Final Indemnity Amount") and (B) either
deliver to the Escrow Agent a certificate signed by the President or any
Vice-President of Parent and the Stockholder Representative setting forth the
Final Indemnity Amount (the "Joint Certificate") or deliver to the Escrow Agent
the court order or judgment by a court of competent jurisdiction, certified by
either the Stockholder Representative or Parent as an original (or as a true and
complete copy thereof) (a "Final Judgment") and (iii) the Escrow Agent shall
deliver to Parent the Final Indemnity Amount from the Assets in the manner set
forth in Section 8(a). If the Stockholder Representative fails so to notify
Parent or the Escrow Agent of the Stockholder Representative's objection to the
Indemnity Amount within such ten business day period, the Indemnity Amount shall
be deemed conclusive and binding on all the parties hereto, whereupon the Escrow
Agent shall make distributions from the Escrow Account in the manner set forth
in Section 8(a).

     (c) Notwithstanding any of the foregoing, the Escrow Account and any
payments hereunder shall be subject to equitable adjustment to reflect through
proportionate increase or decrease any change in the outstanding capital stock
of Parent for any reason, including, without limitation, by reason of any
reclassification, recapitalization, stock split or combination, exchange or
readjustment of shares of Parent Stock, or any stock dividend thereon. Parent
hereby undertakes to notify the Escrow Agent promptly of any event requiring
such equitable adjustment.

     9.  The Stockholder Representative.  (a) Pursuant to the terms of the
Merger Agreement each stockholder of the Company, who has not perfected
statutory dissenters' rights, has granted the Stockholder Representative the
authority to act as agent for each such stockholder in connection with the
transactions contemplated hereunder and to perform all acts required hereby,
including, but not limited to, receiving and delivering all notices, giving all
approvals and waivers, and exercising all other rights of each such stockholder
hereunder.

     (b) In the event of the death or incapacity of the Stockholder
Representative, such other Person as may be designated by the vote or written
consent of a majority in interest of the stockholders of the Company (as set
forth on Exhibit C hereto) shall, upon notice to Parent and the Escrow Agent, be
appointed as the successor Stockholder Representative.

     (c) Parent and the Escrow Agent shall be entitled to rely, without any
investigation or inquiry by Parent or the Escrow Agent, upon all actions by the
Stockholder Representative as having been taken upon the authority of the
stockholders of the Company. Any action by the Stockholder Representative shall
be conclusively deemed to be the action of the stockholders of the Company and
Parent and the Escrow Agent shall not have any liability or responsibility to
the stockholders of the Company for any action taken in reliance thereon.

     (d) The Stockholder Representative shall not be liable to the stockholders
of the Company for any action taken or omitted to be taken hereunder as
Stockholder Representative, except due to the Stockholder Representative's gross
negligence or bad faith. The Stockholders of Genetic MicroSystems shall
indemnify the Stockholder Representative and hold the Stockholder Representative
harmless against any loss, liability or expense incurred without gross
negligence or bad faith on the part of the Stockholder Representative and
arising out of or in connection with the acceptance or administration of the
Stockholder Representative's duties hereunder, including the reasonable fees and
expenses of any legal counsel retained by the Stockholder Representative.

     10.  Termination of the Escrow Account.  (a) Five business days after the
one-year anniversary of the Effective Time (the "Termination Date"), the Escrow
Agent shall distribute all Assets then remaining including any dividends and
distributions not yet distributed pursuant to Section 6 hereof

                                       C-3
<PAGE>   144

(except a sufficient amount of Assets to satisfy any unsatisfied claim specified
in any Officer's Certificate, Joint Certificate or Final Judgment theretofore
delivered to the Escrow Agent) to the stockholders of the Company pro rata in
accordance with the relative ownership percentage of each such stockholder;
provided, however, that if the Escrow Agent shall receive a certificate signed
by the President or any Vice-President of Parent instructing the Escrow Agent
not to distribute such Assets until any unsatisfied indemnification claim
hereunder has been resolved, the Escrow Agent shall hold such Assets until such
time as it receives a certificate signed by the President or any Vice-President
of Parent and the Stockholder Representative and dispose of such Assets in
accordance with the instructions set forth therein.

     (b) It is understood and agreed that no party to this Agreement shall take
any action or omit to take any action pursuant to this Article to the extent
that such action or omission would result in the Merger not qualifying for
pooling-of-interests accounting treatment under GAAP.

     11.  Notices.  All notices, requests and other communications to any party
hereunder shall be in wilting (including facsimile transmission) and shall be
given,

        if to Parent or Merger Sub to:
Affymetrix, Inc.
3380 Central Expressway
Santa Clara, CA 95051
Attention: General Counsel (Vern Norviel)
fax: (408) 481-4709

        with copies to:
Neil T. Anderson
Sullivan & Cromwell
125 Broad Street
New York, NY 10004
fax: (212) 558-3588

        if to the Stockholder Representative to:
Jean Montagu
Genetic MicroSystems, Inc.
34 Commerce Way
Woburn, MA 01801
fax: (781) 932-9433

        with a copy to:
Michael E. Lytton
Palmer & Dodge LLP
One Beacon Street
Boston, MA 02108
fax: (617) 227-4420

                                       C-4
<PAGE>   145

        if to the Escrow Agent to:
Bank One Trust Company, NA
Global Corporate Trust Services
611 Woodward Avenue, M11-8110
Detroit, Michigan 48226
Attention: Amy J. Brehler
Fax: (313) 225-3945

or such other address or facsimile number as such party may hereafter specify
for the purpose by notice to the other parties hereto. All such notices,
requests and other communications shall be deemed received on the date of
receipt by the recipient thereof if received prior to 5 p.m. (Eastern Time), and
such day is a business day, in the place of receipt. Otherwise, any such notice,
request or communication shall be deemed not to have been received until the
next succeeding business day in the place of receipt.

     12.  The Escrow Agent.  (a) The Escrow Agent shall have no duty or
obligation hereunder other than to take such specific actions as are required of
it from time to time under the provisions hereof, and it shall incur no
liability hereunder or in connection herewith for anything whatsoever other than
as a result of its own gross negligence or willful misconduct. The party
primarily responsible for causing any and all losses, claims, liabilities and
expenses, including the reasonable fees of counsel, to the Escrow Agent shall
indemnify, hold harmless and defend the Escrow Agent from and against any and
all losses, claims, liabilities and expenses, including the reasonable fees of
counsel, which it may suffer or incur hereunder, or in connection herewith,
except such as shall result solely and directly from the Escrow Agent's own
gross negligence or willful misconduct; provided, however, that if no party is
primarily responsible for causing such losses, claims, liabilities and expenses,
including the reasonable fees of counsel, Parent and the Stockholder
Representative shall jointly and severally indemnify the Escrow Agent in
accordance with this Section 12. The Escrow Agent shall not be bound in any way
by any agreement or contract among Parent, Merger Sub, the Company and the
Stockholder Representative (whether or not the Escrow Agent has knowledge
thereof) and the only duties and responsibilities of the Escrow Agent shall be
to hold the Assets in accordance with the terms of this Escrow Agreement. All
reasonable fees and expenses of the Escrow Agent shall be paid 50% by the
Stockholder Representative (on behalf of the stockholders of the Company) and
50% by Parent.

     (b) Notwithstanding any provision contained herein to the contrary, the
Escrow Agent, including its officers, directors, employees and agents, shall:

          (i) have no responsibility to inquire into or determine the
     genuineness, authenticity, or sufficiency of any securities, checks, or
     other documents or instruments submitted to it in connection with its
     duties hereunder;

          (ii) be entitled to deem the signatories of any documents or
     instruments submitted to it hereunder as being those purported to be
     authorized to sign such documents or instruments on behalf of the parties
     hereto, and shall be entitled to rely upon the genuineness of the signature
     of such signatories without inquiry and without requiring substantiating
     evidence of any kind;

          (iii) have no responsibility or liability for any diminution in value
     of any assets held hereunder which may result from any investments or
     reinvestments made in accordance with any provision which may be contained
     herein;

          (iv) be entitled to compensation for its services hereunder as per
     Schedule B, which is attached hereto and made a part hereof, and for
     reimbursement of its out-of-pocket expenses including, but not by way of
     limitation, the fees and costs of attorneys or agents which it may

                                       C-5
<PAGE>   146

     find necessary to engage in performance of its duties hereunder, and the
     Escrow Agent shall have, and is hereby granted, a prior lien upon the
     Assets with respect to its unpaid fees and non reimbursed expenses,
     superior to the interests of any other persons or entities; and

          (iv) be under no obligation to invest the deposited funds or the
     income generated thereby until it has received a Form W-9 or W-8, as
     applicable, from each of the parties hereto, regardless of whether any
     party is exempt from reporting or withholding requirements under the
     Internal Revenue Code of 1986, as amended.

     13.  Further Assurances.  Subject to the terms and conditions of this
Agreement, the parties hereto shall use their reasonable best efforts to take,
or cause to be taken, all actions and to do, or cause to be done, all things
necessary or desirable to perform their obligations hereunder including, without
limitation, determining the amount a Parent Indemnified Party shall be entitled
to recover from the Escrow Account and delivering to the Escrow Agent a Joint
Certificate or a Final Judgment upon such determination.

     14.  Successors and Assigns.  The provisions of this Agreement shall be
binding upon and inure to the benefit of the parties hereto and their respective
successors and assigns; provided that no party may assign, delegate or otherwise
transfer any of its rights or obligations under this Agreement without the
written consent of each other party hereto. Any such purported assignment,
delegation or transfer made without such written consent shall be null and void.

     15.  Governing Law.  This Agreement shall be governed by and construed in
accordance with the law of the State of Delaware, without regard to the
conflicts of law rules of such state.

     16.  VENUE; WAIVER OF JURY TRIAL.  THE PARTIES HEREBY IRREVOCABLY SUBMIT TO
THE JURISDICTION OF THE COURTS OF THE STATE OF DELAWARE AND THE FEDERAL COURTS
OF THE UNITED STATES OF AMERICA LOCATED IN THE STATE OF DELAWARE SOLELY IN
RESPECT OF THE INTERPRETATION AND ENFORCEMENT OF THE PROVISIONS OF THE
TRANSACTION AGREEMENTS, AND IN RESPECT OF THE TRANSACTIONS CONTEMPLATED THEREBY,
AND HEREBY WAIVE, AND AGREE NOT TO ASSERT, AS A DEFENSE IN ANY ACTION, SUIT OR
PROCEEDING FOR THE INTERPRETATION OR ENFORCEMENT HEREOF OR OF ANY SUCH DOCUMENT,
THAT IT IS NOT SUBJECT THERETO OR THAT SUCH ACTION, SUIT OR PROCEEDING MAY NOT
BE BROUGHT OR IS NOT MAINTAINABLE IN SAID COURTS OR THAT THE VENUE THEREOF MAY
NOT BE APPROPRIATE OR THAT ANY OF THE TRANSACTION AGREEMENTS MAY NOT BE ENFORCED
IN OR BY SUCH COURTS, AND THE PARTIES HERETO IRREVOCABLY AGREE THAT ALL CLAIMS
WITH RESPECT TO SUCH ACTION OR PROCEEDING SHALL BE HEARD AND DETERMINED IN SUCH
A DELAWARE STATE OR FEDERAL COURT. THE PARTIES HEREBY CONSENT TO AND GRANT ANY
SUCH COURT JURISDICTION OVER THE PERSON OF SUCH PARTIES AND OVER THE SUBJECT
MATTER OF SUCH DISPUTE AND AGREE THAT MAILING OF PROCESS OR OTHER PAPERS IN
CONNECTION WITH ANY SUCH ACTION OR PROCEEDING IN THE MANNER PROVIDED IN SECTION
11 OR IN SUCH OTHER MANNER AS MAY BE PERMITTED BY LAW SHALL BE VALID AND
SUFFICIENT SERVICE THEREOF. EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY
CONTROVERSY WHICH MAY ARISE UNDER THIS AGREEMENT IS LIKELY TO INVOLVE
COMPLICATED AND DIFFICULT ISSUES, AND THEREFORE EACH SUCH PARTY HEREBY
IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY RIGHT SUCH PARTY MAY HAVE TO A TRIAL
BY JURY IN RESPECT OF ANY LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF OR
RELATING TO THIS AGREEMENT, OR THE TRANSACTIONS CONTEMPLATED HEREBY. EACH PARTY
CERTIFIES AND ACKNOWLEDGES THAT (i) NO REPRESEN-

                                       C-6
<PAGE>   147

TATIVE, AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR
OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO
ENFORCE THE FOREGOING WAIVER, (ii) EACH PARTY UNDERSTANDS AND HAS CONSIDERED THE
IMPLICATIONS OF THIS WAIVER, (iii) EACH PARTY MAKES THIS WAIVER VOLUNTARILY, AND
(iv) EACH PARTY HAS BEEN INDUCED TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER
THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 16.

     17.  Counterparts; Effectiveness.  This Agreement may be signed in any
number of counterparts, each of which shall be an original, with the same effect
as if the signatures thereto and hereto were upon the same instrument. This
Agreement shall become effective when each party hereto shall have received
counterparts hereof signed by all of the other parties hereto. No provision of
this Agreement is intended to confer any rights, benefits, remedies, obligations
or liabilities hereunder upon any Person other than the parties hereto and their
respective successors and assigns.

     18.  Resignation or Removal of the Escrow Agent.  (a) The Escrow Agent may
resign as such upon 30 days' prior written notice to the other parties hereto.
The Escrow Agent may be removed and replaced upon 30 days' prior written notice
to the Escrow Agent from Parent and the Stockholder Representative. If the
Escrow Agent resigns or is removed, the duties of the Escrow Agent shall
terminate 30 days after receipt of such notice (or as of such earlier date as
may be agreed by the parties hereto) and the Escrow Agent shall then deliver the
balance of the Assets then in its possession to a successor escrow agent as
shall be appointed by the other parties hereto as evidenced by a written notice
filed with the Escrow Agent.

     (b) If the other parties hereto are unable to agree upon a successor to the
Escrow Agent or shall have failed to appoint such successor prior to the
expiration of 30 days following receipt of the notice of resignation or removal,
the Escrow Agent may petition any court of competent jurisdiction for the
appointment of a successor escrow agent or for other appropriate relief, and any
such resulting appointment shall be binding upon all of the parties hereto. Upon
acknowledgment by any successor escrow agent of the receipt of the balance of
the Assets in escrow, the Escrow Agent shall be fully released and relieved of
all duties, responsibilities, and obligations under this Agreement.

     19.  Entire Agreement.  This Agreement and the Merger Agreement constitute
the entire agreement among the parties with respect to the subject matter of
this Agreement and supersede all prior agreements and understandings, both oral
and written, among the parties with respect to the subject matter of this
Agreement.

     20.  Captions.  The captions herein are included for convenience of
reference only and shall be ignored in the construction or interpretation
hereof.

     21.  Severability.  If any term, provision, covenant or restriction of this
Agreement is held by a court of competent jurisdiction or other authority to be
invalid, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions of this Agreement shall remain in full force and
effect and shall in no way be affected, impaired or invalidated so long as the
economic or legal substance of the transactions contemplated hereby is not
affected in any manner materially adverse to any party. Upon such a
determination, the parties shall negotiate in good faith to modify this
Agreement so as to effect the original intent of the parties as closely as
possible in an acceptable manner so that the transactions contemplated hereby be
consummated as originally contemplated to the fullest extent possible.

     22.  Specific Performance.  The parties hereto agree that irreparable
damage would occur if any provision of this Agreement were not performed in
accordance with the terms hereof and that the parties shall be entitled to an
injunction or injunctions to prevent breaches of this Agreement or to

                                       C-7
<PAGE>   148

enforce specifically the performance of the terms and provisions hereof in any
court set forth in Section 16 in addition to any other remedy to which they are
entitled at law or in equity.

     23.  Amendments; Waiver.  This Agreement may be amended, modified or
supplemented in each case only by a written instrument duly executed by or on
behalf of the parties to this Agreement. Any of the terms of this Agreement may
be waived only by a written instrument duly executed by or on behalf of the
parties against whom enforcement is sought and no such waiver by any party of
any term or condition contained in this Agreement shall be deemed to be a waiver
of the same or any other term or condition of this Agreement on any future
occasion.

                                       C-8
<PAGE>   149

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the day and year first above written.

                                          AFFYMETRIX, INC.

                                          By: /s/ VERN NORVIEL
                                            ------------------------------------
                                              Name: Vern Norviel
                                              Title: Senior Vice President and
                                                     General Counsel

                                          GMS ACQUISITION, INC.

                                          By: /s/ SUSAN E. SIEGEL
                                            ------------------------------------
                                              Name: Susan E. Siegel
                                              Title: President

                                          GENETIC MICROSYSTEMS, INC.

                                          By: /s/ JEAN MONTAGU
                                            ------------------------------------
                                              Name: Jean Montagu
                                              Title: President

                                          STOCKHOLDER REPRESENTATIVE

                                          /s/ JEAN MONTAGU
                                          --------------------------------------
                                          Jean Montagu

                                          BANK ONE TRUST COMPANY, NA

                                          By: /s/ AMY J. BREHLER
                                            ------------------------------------
                                              Name: Amy J. Brehler
                                              Title: Authorized Officer

                                       C-9
<PAGE>   150

                                                                      APPENDIX D

                      FORM OF STOCKHOLDER VOTING AGREEMENT

     FORM OF STOCKHOLDER VOTING AGREEMENT, dated as of September 10, 1999 (this
"Agreement"), between                ("Stockholder") and Affymetrix, Inc., a
Delaware corporation ("Purchaser").

     WHEREAS, Genetic MicroSystems, Inc., a Massachusetts corporation (the
"Company"), Purchaser, GMS Acquisition, Inc., a Massachusetts corporation and a
wholly owned subsidiary of Purchaser ("Merger Sub") and Jean Montagu as
"Stockholder Representative", are contemporaneously herewith entering into an
Agreement and Plan of Merger, dated the date hereof (the "Merger Agreement"),
which provides, among other things, for the merger of the Company with and into
Merger Sub (the "Merger");

     WHEREAS, as a condition to their willingness to enter into the Merger
Agreement, Purchaser and Merger Sub have requested that Stockholder make certain
agreements with respect to the aggregate number of shares of Common Stock, no
par value per share ("Shares"), of the Company set forth opposite the
Stockholder's name on Schedule A attached hereto as to all of which Shares the
Stockholder has sole voting and dispositive power (such Shares, as such Shares
may be adjusted by any stock dividend, stock split, reorganization, combination
or exchange of shares, merger, consolidation, reorganization or other change or
transaction of or by the Company, being referred to herein as the "Subject
Shares"), upon the terms and subject to the conditions hereof; and

     WHEREAS, in order to induce Purchaser and Merger Sub to enter into the
Merger Agreement, Stockholder is willing to make certain agreements with respect
to the Subject Shares;

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
and agreements set forth herein, the parties hereto agree as follows:

     1. Voting Agreements; Proxy.

          (a) For so long as this Agreement is in effect, at any meeting of
     stockholders of the Company, however called, and in any action by consent
     of the stockholders of the Company or in any other circumstances upon which
     a vote, consent or other approval is sought, Stockholder shall vote (or
     cause to be voted), or, if applicable, give consent or approval with
     respect to, all of the Subject Shares (and any other Shares over which
     Stockholder has voting power whether issued heretofore or hereafter) that
     Stockholder has the right to vote or is able to control the voting of in
     favor of the Merger Agreement and the Merger and any other transaction
     contemplated by the Merger Agreement, as such agreement may be modified or
     amended from time to time. Any such vote shall be cast or consent shall be
     given in accordance with such procedures relating thereto as shall ensure
     that it is duly counted for purposes of determining that a quorum is
     present and for purposes of recording the results of such vote or consent.

          (b) For so long as this Agreement is in effect, at any meeting of
     stockholders of the Company, however called, and in any action by consent
     of the stockholders of the Company or in any other circumstances upon which
     a vote, consent or other approval is sought, Stockholder shall vote (or
     cause to be voted), or, if applicable, give consent or approval with
     respect to, all of the Subject Shares (and any other Shares over which
     Stockholder has voting power whether issued heretofore or hereafter) that
     Stockholder has the right to vote, or is able to control the voting of,
     against (i) any merger or merger agreement (other than the Merger and the
     Merger Agreement) or any other proposal that would constitute an
     Acquisition Proposal (as defined in

                                       D-1
<PAGE>   151

     the Merger Agreement), (ii) any amendment to the Company's articles of
     organization or by-laws and (iii) any other amendment, proposal or
     transaction involving the Company, which amendment or other proposal or
     transaction would in any manner impede, frustrate, prevent or nullify the
     Merger or which is reasonably likely to result in any of the conditions to
     the Company's obligations under the Merger Agreement not being fulfilled.

          (c) In furtherance of the transactions contemplated hereby and by the
     Merger Agreement, and in order to secure the performance of Stockholder of
     his duties under this Agreement, Stockholder hereby grants to Purchaser and
     its designees, an irrevocable proxy, or, if applicable, a power of
     attorney, and irrevocably appoints Purchaser or its designees, with full
     power of substitution, its attorney and proxy to vote or, if applicable, to
     give consent with respect to, all Subject Shares with regard to any of the
     matters referred to in paragraph (a) above at any meeting of the
     stockholders of the Company, however called, or in connection with any
     action by written consent by the stockholders of the Company. Stockholder
     acknowledges and agrees that such proxy is coupled with an interest,
     constitutes, among other things, an inducement for Purchaser to enter into
     the Merger Agreement, is irrevocable and shall not be terminated by
     operation of law or otherwise upon the occurrence of any event (other than
     as provided in Section 16 hereof) and that no subsequent proxies with
     respect to the Subject Shares shall be given (and if given shall not be
     effective).

          (d) No Limitation on Discretion as Director. Nothing in this Agreement
     shall be deemed to apply to, or to limit in any manner, the discretion of
     the Stockholder with respect to any action to be taken (or omitted) by the
     Stockholder in the Stockholder's fiduciary capacity as a director or
     officer of the Company including, without limitation, in connection with
     any action taken in accordance with Section 9.3(a) of the Merger Agreement;
     provided, however, it is agreed and understood by the parties to this
     Agreement that the obligations, covenants and agreements of Stockholder
     contained in this Agreement are separate and apart from the Stockholder's
     fiduciary duties as a director or officer of the Company and no fiduciary
     obligations that Stockholder may have as a director or officer of the
     Company shall countermand the obligations, covenants and agreements of
     Stockholder, in his capacity as a stockholder of the Company, contained in
     this Agreement.

     2. Covenants.  (a) From and after the date of this Agreement, Stockholder
agrees not to, and to use best efforts to cause any investment banker, attorney
or other adviser or representative of Stockholder not to (i) sell, transfer,
pledge, assign, hypothecate, encumber, tender or otherwise dispose of, or enter
into any contract, option or other arrangement with respect to the sale,
transfer, pledge, assignment, hypothecation, encumbrance, tender or other
disposition of the Subject Shares; (ii) grant any proxies with respect to any
Subject Shares, deposit any such Subject Shares into a voting trust or enter
into a voting or option agreement with respect to any of such Subject Shares;
(iii) except to the extent permitted by Section 7.2 of the Merger Agreement with
respect to Stockholder's position as an officer or director of the Company,
directly or indirectly, solicit, initiate, encourage or otherwise facilitate any
inquiries or the making of any proposal or offer with respect to an Acquisition
Proposal or engage in any negotiation concerning, or provide any confidential
information or data to, or have any discussions with any person relating to an
Acquisition Proposal; or (iv) take any action which would make any
representation or warranty of Stockholder herein untrue or incorrect or prevent,
burden or materially delay the consummation of the transactions contemplated by
this Agreement. As used in this Agreement, "person" shall have the meaning
specified in Sections 3(a)(9) and 13(d)(3) of the Securities Exchange Act of
1934, as amended (the "Exchange Act").

                                       D-2
<PAGE>   152

     3. Representations and Warranties of Stockholder.  Stockholder represents
and warrants to Purchaser that:

          (a) Capacity; No Violations. Stockholder has the necessary authority
     to enter into this Agreement and to consummate the transactions
     contemplated hereby. This Agreement has been duly executed and delivered by
     Stockholder, and constitutes a valid and binding agreement of Stockholder
     enforceable against Stockholder in accordance with its terms; and such
     execution and delivery and performance by Stockholder of this Agreement
     will not (i) conflict with, require a consent, waiver or approval under, or
     result in a breach or default under, any of the terms of any governing
     instrument, contract, commitment or other obligation of Stockholder or to
     which Stockholder is a party or by which Stockholder is, or the Subject
     Shares are, bound; (ii) violate any order, writ, injunction, decree or
     statute, or any law, rule or regulation applicable to Stockholder or the
     Subject Shares; or (iii) result in the creation of, or impose any
     obligation on Stockholder to create, any Lien upon the Subject Shares. In
     this Agreement, "Lien" shall mean any lien, pledge, security interest,
     claim, third party right or other encumbrance.

          (b) Subject Shares. Except as set forth on Schedule B to this
     Agreement, (i) Stockholder is the record holder of, has sole voting and
     dispositive power over, and has good and valid title to, the Subject Shares
     free and clear of all Liens and (ii) there are no options or rights to
     acquire or other contracts (including proxies, voting trusts or voting
     agreements) relating to the Subject Shares to which Stockholder is a party.
     Except as otherwise disclosed on Schedule A to this Agreement, as of the
     date hereof, the Subject Shares are the only shares of any class of capital
     stock of the Company which Stockholder has the right, power or authority
     (sole or shared) to sell or vote, and, other than the options on Shares
     held by Stockholder as of the date hereof, Stockholder does not have any
     right to acquire, nor is it the beneficial owner of, any other shares of
     any class of capital stock of the Company or any securities convertible
     into or exchangeable or exercisable for any shares of any class of capital
     stock of the Company.

          (c) Investment Intent. Stockholder is acquiring the shares of Common
     Stock of purchaser to be received by Stockholder in the Merger (the
     "Purchaser Shares") for its own account and not with a view to their
     distribution within the meaning of Section 2.11 of the Securities Act of
     1933 ("Securities Act") in any manner that would be in violation of the
     Securities Act. Stockholder has not, directly or indirectly, offered the
     Purchaser Shares to anyone or solicited any offer to buy the Purchaser
     Shares from anyone, so as to bring such offer and sale of the Purchaser
     Shares by Stockholder within the registration requirements of the
     Securities Act. Stockholder will not sell, convey, transfer or offer for
     sale any of the Purchaser Shares except upon compliance with the Securities
     Act and any applicable state securities laws or pursuant to any exemption
     therefrom.

          (d) Accredited Investor Status. Stockholder is and at the time of
     delivery of any Purchaser Shares will be an "accredited investor" within
     the meaning of Regulation D promulgated under the Securities Act.
     Stockholder has, and at the time of such delivery will have, such knowledge
     and experience in financial and business matters that Stockholder is and
     will be capable of evaluating the merits and risks of an investment in
     Purchaser Shares and represents and warrants that Stockholder has not
     received and will not receive any representations from Purchaser or any of
     its officers or representatives with regard to the Purchaser Shares or
     Purchaser.

     4. Adjustments; Additional Shares.  In the event (i) of any stock dividend,
stock split, recapitalization, reclassification. combination or exchange of
Shares on, of or affecting the Subject Shares, or (ii) Stockholder shall become
the beneficial owner of any additional Shares or other securities entitling the
holder thereof to vote or give consent with respect to the matters set forth in
Section 1 hereof, then such Shares held by Stockholder immediately following the
effectiveness of the

                                       D-3
<PAGE>   153

events described in clause (i) or Stockholder becoming the beneficial owner of
the Shares or other securities, as described in clause (ii) shall become Subject
Shares hereunder.

     5. Expenses.  Each party hereto shall pay its own expenses incurred in
connection with this Agreement.

     6. Specific Performance.  Stockholder acknowledges and agrees that if it
fails to perform any of its obligations under this Agreement immediate and
irreparable harm or injury would be caused to Purchaser for which money damages
would not be an adequate remedy. In such event, Stockholder agrees that
Purchaser shall have the right, in addition to any other rights it may have, to
specific performance of this Agreement. Accordingly, if Purchaser should
institute an action or proceeding seeking specific enforcement of the provisions
hereof, Stockholder hereby waives the claim or defense that Purchaser has an
adequate remedy at law and hereby agrees not to assert in any such action or
proceeding the claim or defense that such a remedy at law exists. Stockholder
further agrees to waive any requirements for the securing or posting of any bond
in connection with obtaining any such equitable relief.

     7. Appointment of Stockholder Representative.  Stockholder hereby consents
in all respects to the appointment of Jean Montagu as Stockholder Representative
and to the performance by the Stockholder Representative of all rights and
obligations conferred on the Stockholder Representative under the Merger
Agreement and the Escrow Agreement.

     8. Notices.  All notices or other communications under this Agreement shall
be in writing and shall be deemed duly given, effective (i) three business days
later, if sent by registered or certified mail, return receipt requested,
postage prepaid, (ii) when sent, if sent by facsimile, provided that the
facsimile is promptly confirmed by telephone confirmation thereof, (iii) when
served, if delivered personally to the intended recipient, and (iv) one business
day later, if sent by overnight delivery via a national courier service, and in
each case, addressed to the intended recipient at the address set forth in the
preamble hereof. Any party may change the address to which notices or other
communications hereunder are to be delivered by giving the other party notice in
the manner herein set forth:

          If to the Purchaser:

          Affymetrix, Inc.
          3380 Central Expressway
          Santa Clara, CA 95051
          Attention: General Counsel (Vern Norviel)
          Phone: (408) 731-5035
          Fax: (408) 481-4709

          With a copy to:

          Sullivan & Cromwell
          125 Broad Street
          New York, New York 10004
          Attention: Neil T. Anderson
          Phone: (212) 558-4000
          Fax: (212) 558-3588

          If to Stockholder:

          To the address for notice set forth on Schedule A to this Agreement.

                                       D-4
<PAGE>   154

          With a copy to:

          Palmer & Dodge LLP
          One Beacon Street
          Boston, MA 02115
          Attention: Michael E. Lytton
          Phone: (617) 573-0100
          Fax: (617) 227-4420

     9. Parties in Interest. This Agreement shall inure to the benefit of and be
binding upon the parties named herein and their respective successors and
assigns; provided, however, that such successor in interest or assigns shall
agree to be bound by the provisions of this Agreement. Nothing in this
Agreement, express or implied, is intended to confer upon any Person other than
Purchaser, Stockholder or their successors or assigns, any rights or remedies
under or by reason of this Agreement.

     10. Entire Agreement; Amendments. This Agreement contains the entire
agreement between Stockholder and Purchaser with respect to the subject matter
hereof and supersedes all prior and contemporaneous agreements and
understandings, oral or written, with respect to such transactions. This
Agreement may not be changed, amended or modified orally, but may be changed
only by an agreement in writing signed by the party against whom any waiver,
change, amendment, modification or discharge may be sought.

     11. Assignment. No party to this Agreement may assign any of its rights or
obligations under this Agreement without the prior written consent of the other
party hereto, except that Purchaser may assign its rights and obligations
hereunder to any of its direct or indirect wholly owned subsidiaries (including
Merger Sub), but no such transfer shall relieve Purchaser of its obligations
hereunder if such transferee does not perform such obligations.

     12. Further Assurances. The Stockholder will, from time to time, execute
and deliver, or cause to be executed and delivered, such additional or further
transfers, assignments, endorsements, consents and other instruments as
Purchaser may reasonably request for the purpose of effectively carrying out the
transactions contemplated by this Agreement.

     13. Headings. The section headings herein are for convenience only and
shall not affect the construction of this Agreement.

     14. Counterparts. This Agreement may be executed in any number of
counterparts, each of which, when executed, shall be deemed to be an original
and all of which together shall constitute one and the same document.

     15. Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware (regardless of the laws that
might otherwise govern under applicable Delaware principles of conflicts of
law).

     16. Termination. This Agreement shall terminate at the earlier of (i) the
Effective Time (as defined in the Merger Agreement) and (ii) the termination of
the Merger Agreement.

                                       D-5
<PAGE>   155

     IN WITNESS WHEREOF, Purchaser and Stockholder have caused this Agreement to
be duly executed and delivered on the day and year first above written.

                                          AFFYMETRIX, INC.

                                          By:
                                            ------------------------------------
                                              Name:
                                              Title:

                                          --------------------------------------
                                                      [Stockholder]

                                       D-6
<PAGE>   156

                                                                      APPENDIX E

                  MASSACHUSETTS LAW REGARDING APPRAISAL RIGHTS

SECTION 86.  SECTIONS APPLICABLE TO APPRAISAL; PREREQUISITES

     If a corporation proposes to take a corporate action as to which any
section of this chapter provides that a stockholder who objects to such action
shall have the right to demand payment for his shares and an appraisal thereof,
sections eighty-seven to ninety-eight, inclusive, shall apply except as
otherwise specifically provided in any section of this chapter. Except as
provided in sections eighty-two and eight-three, no stockholder shall have such
right unless (1) he files with the corporation before the taking of the vote of
the shareholders on such corporate action, written objection to the proposed
action stating that he intends to demand payment for his shares if the action is
taken and (2) his shares are not voted in favor of the proposed action.

SECTION 87.  STATEMENT OF RIGHTS OF OBJECTING STOCKHOLDERS IN NOTICE OF MEETING;
             FORM

     The notice of the meeting of stockholders at which the approval of such
proposed action is to be considered shall contain a statement of the rights of
objecting stockholders. The giving of such notice shall not be deemed to create
any rights in any stockholder receiving the same to demand payment for his
stock, and the directors may authorize the inclusion in any such notice of a
statement of opinion by the management as to the existence or non-existence of
the right of the stockholders to demand payment for their stock on account of
the proposed corporate action. The notice may be in such form as the directors
or officers calling the meeting deem advisable, but the following form of notice
shall be sufficient to comply with this section:

     "If the action proposed is approved by the stockholders at the meeting and
effected by the corporation, any stockholder (1) who files with the corporation
before the taking of the vote on the approval of such action, written objection
to the proposed action stating the he intends to demand payment for his shares
if the action is taken and (2) whose shares are not voted in favor of such
action has or may have the right to demand in writing from the corporation (or,
in the case of a consolidation or merger, the name of the resulting or surviving
corporation shall be inserted), within twenty days after the date of mailing to
him of notice in writing that the corporate action has become effective,
payments for his shares and an appraisal of the value thereof. Such corporation
and any such stockholder shall in such cases have the rights and duties and
shall follow the procedure set forth in sections 88 to 98, inclusive, of chapter
156B of the General Laws of Massachusetts."

SECTION 88.  NOTICE OF EFFECTIVENESS OF ACTION OBJECTED TO

     The corporation taking such action, or in the case of a merger or
consolidation the surviving or resulting corporation, shall, within ten days
after the date on which such corporate action became effective, notify each
stockholder who filed a written objection meeting the requirements of section
eighty-six and whose shares were not voted in favor of the approval of such
action, that the action approved at the meeting of the corporation of which he
is a stockholder has become effective. The giving of such notice shall not be
deemed to create any rights in any stockholder receiving the same to demand
payment for his stock. The notice shall be sent by registered or certified mail,
addressed to the stockholder at his last known address as it appears in the
records of the corporation.

                                       E-1
<PAGE>   157

SECTION 89.  DEMAND FOR PAYMENT; TIME FOR PAYMENT

     If within twenty days after the date of mailing of a notice under
subsection (e) of section eight-two, subsection (f) of section eighty-three, or
section eighty-eight, any stockholder to whom the corporation was required to
give such notice shall demand in writing from the corporation taking such
action, or in the case of a consolidation or merger from the resulting or
surviving corporation, payment for his stock, the corporation upon which such
demand is made shall pay to him the fair value of his stock within thirty days
after the expiration of the period during which such demand may be made.

SECTION 90.  DEMAND FOR DETERMINATION OF VALUE; BILL IN EQUITY; VENUE

     If during the period of thirty days provided for in section eighty-nine the
corporation upon which such demand is made and any such objecting stockholder
fail to agree as to the value of such stock, such corporation or any such
stockholder may within four months after the expiration of such thirty-day
period demand a determination of the value of the stock of all such objecting
stockholders by a bill in equity filed in the superior court in the county where
the corporation in which such objecting stockholder held stock had or has its
principal office in the commonwealth.

SECTION 91.  PARTIES TO SUIT TO DETERMINE VALUE; SERVICE

     If the bill is filed by the corporation, it shall name as parties
respondent all stockholders who have demanded payment for their shares and with
whom the corporation has not reached agreement as to the value thereof. If the
bill is filed by a stockholder, he shall bring the bill in his own behalf and in
behalf of all other stockholders who have demanded payment for their shares and
with whom the corporation has not reached agreement as to the value thereof, and
service of the bill shall be made upon the corporation by subpoena with a copy
of the bill annexed. The corporation shall file with its answer a duly verified
list of all such other stockholders, and such stockholders shall thereupon be
deemed to have been added as parties to the bill. The corporation shall give
notice in such form and returnable on such date as the court shall order to each
stockholder party to the bill by registered or certified mail, addressed to the
last known address of such stockholder as shown in the records of the
corporation, and the court may order such additional notice by publication or
otherwise as it deems advisable. Each stockholder who makes demand as provided
in section eighty-nine shall be deemed to have consented to the provisions of
this section relating to notice, and the giving of notice by the corporation to
any such stockholder in compliance with the order of the court shall be a
sufficient service of process on him. Failure to give notice to any stockholder
making demand shall not invalidate the proceedings as to other stockholders to
whom notice was properly given, and the court may at any time before the entry
of a final decree make supplementary orders of notice.

SECTION 92.  DECREE DETERMINING VALUE AND ORDERING PAYMENT; VALUATION DATE

     After hearing the court shall enter a decree determining the fair value of
the stock of those stockholders who have become entitled to the valuation of and
payment for their shares, and shall order the corporation to make payment of
such value, together with interest, if any, as hereinafter provided, to the
stockholders entitled thereto upon the transfer by them to the corporation of
the certificates representing such stock if certificated or, if uncertificated,
upon receipt of an instruction transferring such stock to the corporation. For
this purpose, the value of the shares shall be determined as of the day
preceding the date of the vote approving the proposed corporate action and

                                       E-2
<PAGE>   158

shall be exclusive of any element of value arising from the expectation or
accomplishment of the proposed corporate action.

SECTION 93.  REFERENCE TO SPECIAL MASTER

     The court in its discretion may refer the bill or any question arising
thereunder to a special master to hear the parties, make findings and report the
same to the court, all in accordance with the usual practice in suits in equity
in the superior court.

SECTION 94.  NOTATION ON STOCK CERTIFICATES OF PENDENCY OF BILL

     On motion the court may order stockholder parties to the bill to submit
their certificates of stock to the corporation for the notation thereon of the
pendency of the bill and may order the corporation to note such pendency in its
records with respect to any uncertificated shares held by such stockholders
parties, and may on motion dismiss the bill as to any stockholder who fails to
comply with such order.

SECTION 95.  COSTS; INTEREST

     The costs of the bill, including the reasonable compensation and expenses
of any master appointed by the court, but exclusive of fees of counsel or of
experts retained by any party, shall be determined by the court and taxed upon
the parties to the bill, or any of them, in such manner as appears to be
equitable, except that all costs of giving notice to stockholders as provided in
this chapter shall be paid by the corporation. Interest shall be paid upon any
award from the date of the vote approving the proposed corporate action, and the
court may on application of any interested party determine the amount of
interest to be paid in the case of any stockholder.

SECTION 96.  DIVIDENDS AND VOTING RIGHTS AFTER DEMAND FOR PAYMENT

     Any stockholder who has demanded payment for his stock as provided in this
chapter shall not thereafter be entitled to notice of any meeting of
stockholders or to vote such stock for any purpose and shall not be entitled to
the payment of dividends or other distribution on the stock (except dividends or
other distributions payable to stockholders of record at a date which is prior
to the date of the vote approving the proposed corporate action) unless:

          (1) bill shall not be filed within the time provided in section
     ninety;

          (2) A bill, if filed, shall be dismissed as to such stockholder; or

          (3) Such stockholder shall with the written approval of the
     corporation, or in the case of a consolidation or merger, the resulting or
     surviving corporation, deliver to it a written withdrawal of his objections
     to and an acceptance of such corporate action.

     Notwithstanding the provisions of clauses (1) to (3), inclusive, said
stockholder shall have only the rights of a stockholder who did not so demand
payment for his stock as provided in this chapter.

SECTION 97.  STATUS OF SHARES PAID FOR

     The shares of the corporation paid for by the corporation pursuant to the
provisions of this chapter shall have the status of treasury stock, or in the
case of a consolidation or merger the shares or the securities of the resulting
or surviving corporation into which the shares of such objecting

                                       E-3
<PAGE>   159

stockholder would have been converted had he not objected to such consolidation
or merger shall have the status of treasury stock or securities.

SECTION 98.  EXCLUSIVE REMEDY; EXCEPTION

     The enforcement by a stockholder of his right to receive payment for his
shares in the manner provided in this chapter shall be an exclusive remedy
except that this chapter shall not exclude the right of such stockholder to
bring or maintain an appropriate proceeding to obtain relief on the ground that
such corporate action will be or is illegal or fraudulent as to him.

                                       E-4
<PAGE>   160

                                                                      APPENDIX F

                           GENETIC MICROSYSTEMS, INC.

                         INDEX TO FINANCIAL STATEMENTS

<TABLE>
<S>                                                           <C>
Report of Independent Auditors..............................   F-2
Audited Financial Statements -- Year ended December 31, 1998
  and period from August 7, 1997 (date of inception) to
  December 31, 1997
Balance Sheets..............................................   F-3
Statements of Operations and Comprehensive Loss.............   F-4
Statements of Shareholders' Equity (Deficit)................   F-5
Statements of Cash Flows....................................   F-6
Notes to Financial Statements...............................   F-7
Unaudited Condensed Financial Statements -- Six month
  periods ended July 3, 1999 and June 30, 1998
Condensed Balance Sheet.....................................  F-14
Condensed Statements of Operations and Comprehensive Loss...  F-15
Condensed Statements of Cash Flows..........................  F-16
Notes to Condensed Financial Statements.....................  F-17
</TABLE>

                                       F-1
<PAGE>   161

                         REPORT OF INDEPENDENT AUDITORS

Board of Directors
Genetic MicroSystems, Inc.

     We have audited the accompanying balance sheets of Genetic MicroSystems,
Inc. (the Company) as of December 31, 1998 and 1997, and the related statements
of operations and comprehensive loss, shareholders' equity (deficit), and cash
flows for the year ended December 31, 1998 and the period from August 7, 1997
(date of inception) to December 31, 1997. These financial statements are the
responsibility of the Company's management. Our responsibility is to express an
opinion on these financial statements based on our audits.

     We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.

     In our opinion, the financial statements referred to above present fairly,
in all material respects, the financial position of the Company as of December
31, 1998 and 1997, and the results of its operations and its cash flows for the
year ended December 31, 1998 and the period from August 7, 1997 (date of
inception) to December 31, 1997, in conformity with generally accepted
accounting principles.

                                          /s/ Ernst & Young LLP

Boston, Massachusetts
January 12, 1999

                                       F-2
<PAGE>   162

                           GENETIC MICROSYSTEMS, INC.

                                 BALANCE SHEETS

<TABLE>
<CAPTION>
                                                                     DECEMBER 31
                                                              -------------------------
                                                                 1998          1997
                                                              ----------    -----------
<S>                                                           <C>           <C>
ASSETS
Current assets:
  Cash and cash equivalents.................................  $4,365,446    $    33,654
  Available-for-sale equity securities......................                  1,518,000
  Accounts receivable.......................................     213,575
  Inventories...............................................     421,809
  Prepaid expenses and other assets.........................      87,356         11,115
                                                              ----------    -----------
          Total current assets..............................   5,088,186      1,562,769
Property and equipment, net.................................     605,811         94,766
Deposits....................................................      64,000
                                                              ----------    -----------
                                                              $5,757,997    $ 1,657,535
                                                              ==========    ===========
LIABILITIES AND SHAREHOLDERS' EQUITY
Current liabilities:
  Accounts payable..........................................  $  252,569    $   138,152
  Accrued expenses..........................................     291,159         46,342
  Due to shareholder........................................                    120,000
  Deferred tax liability....................................                    540,665
                                                              ----------    -----------
          Total current liabilities.........................     543,728        845,159
Deferred rent...............................................      49,529
Common stock purchase rights................................   3,000,000
Series B Redeemable Convertible Preferred Stock, $.01 par
  value; 582,353 shares authorized; 347,134 shares issued
  and outstanding (aggregate liquidation preference of
  $2,950,639)...............................................   2,950,639
Shareholders' equity (deficit):
  Series A Convertible Preferred Stock, $.01 par value;
     2,054,000 shares authorized; 2,000,000 shares issued
     and outstanding (aggregate liquidation preference of
     $4,000,000)............................................      20,000
  Common Stock, no par value; 5,000,000 shares in 1998 and
     200,000 shares in 1997 authorized; 1,048,000 shares in
     1998 and 10,000 shares in 1997 issued..................     215,600        120,000
  Additional paid-in capital................................   3,075,218      1,587,924
  Notes receivable from shareholders........................    (159,840)
  Treasury Stock (46,864 shares of Common Stock, at cost)...     (12,933)
  Unrealized loss on available-for-sale equity securities...                   (641,777)
  Accumulated deficit.......................................  (3,923,944)      (253,771)
                                                              ----------    -----------
          Total shareholders' equity (deficit)..............    (785,899)       812,376
                                                              ----------    -----------
                                                              $5,757,997    $ 1,657,535
                                                              ==========    ===========
</TABLE>

     See accompanying notes.

                                       F-3
<PAGE>   163

                           GENETIC MICROSYSTEMS, INC.

                STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

<TABLE>
<CAPTION>
                                                                             PERIOD FROM
                                                          YEAR ENDED        AUGUST 7, 1997
                                                         DECEMBER 31,    (DATE OF INCEPTION)
                                                             1998        TO DECEMBER 31, 1997
                                                         ------------    --------------------
<S>                                                      <C>             <C>
Revenues:
Net product sales......................................  $   287,625
  Licensing revenue....................................       99,980
                                                         -----------
                                                             387,605
Costs and expenses:
  Costs of sales.......................................      367,605
  Research and development.............................    2,479,915          $ 421,694
  Selling, general and administrative..................    1,877,541             59,159
                                                         -----------          ---------
                                                           4,725,061            480,853
                                                         -----------          ---------
Loss from operations...................................   (4,337,456)          (480,853)
Other income (expense):
  Gain (loss) on sale of available-for-sale equity
     securities........................................     (664,505)            57,082
  Interest and dividend income.........................       63,172
                                                         -----------          ---------
                                                            (601,333)            57,082
                                                         -----------          ---------
Loss before income tax benefit.........................   (4,938,789)          (423,771)
Income tax benefit.....................................    1,268,616            170,000
                                                         -----------          ---------
Net loss...............................................   (3,670,173)          (253,771)
Change in unrealized loss on available-for-sale equity
  securities...........................................      641,777           (641,777)
                                                         -----------          ---------
Comprehensive net loss.................................  $(3,028,396)         $(895,548)
                                                         ===========          =========
Loss per share:
  Net loss per share -- basic and diluted..............  $      6.21          $   25.38
                                                         ===========          =========
  Comprehensive net loss per share -- basic and
     diluted...........................................  $      5.12          $   89.55
                                                         ===========          =========
  Weighted average common shares -- basic and
     diluted...........................................      591,227             10,000
                                                         ===========          =========
</TABLE>

See accompanying notes.

                                       F-4
<PAGE>   164

                           GENETIC MICROSYSTEMS, INC.

                  STATEMENTS OF SHAREHOLDERS' EQUITY (DEFICIT)
<TABLE>
<CAPTION>

                                                                                                                  NOTES
                                                SERIES A CONVERTIBLE                              ADDITIONAL    RECEIVABLE
                                                   PREFERRED STOCK           COMMON STOCK          PAID-IN         FROM
                                                  SHARES     AMOUNTS     SHARES       AMOUNTS      CAPITAL     SHAREHOLDERS
                                                ----------   --------   ---------   -----------   ----------   ------------
<S>                                             <C>          <C>        <C>         <C>           <C>          <C>
Issuance of Common Stock in exchange for
contribution of available-for-sale securities
to capital, net of deferred taxes of
$1,138,616....................................                             10,000   $   120,000   $1,587,924
Unrealized loss on available-for-sale
  securities, net of deferred taxes of
  $427,951....................................
Net loss for the period from August 7, 1997
  (date of inception) to December 31, 1997....
                                                                        ---------   -----------   ----------
BALANCE AT DECEMBER 31, 1997..................                             10,000       120,000    1,587,924
Change in unrealized loss.....................
Contribution of available-for-sale securities
  to capital, net of deferred taxes of
  $300,000....................................                                                       450,000
Contribution of cash..........................                                                        10,082
Issuance of Common Stock in exchange for
  capital contributions.......................                            140,000     2,048,006   (2,048,006)
Conversion of Common Stock into Series A
  Convertible Preferred Stock in 1998.........  1,500,000    $15,000     (150,000)   (2,168,006)   2,153,006
Issuance of Series A Convertible Preferred
  Stock in 1998...............................    500,000      5,000                                 952,212
Issuance of Common Stock......................                          1,048,000       215,600      (30,000)   $(213,600)
Repurchase of Treasury Stock..................                                                                     12,600
Net loss......................................
Collection of notes receivable from
  stockholders................................                                                                     41,160
                                                ---------    -------    ---------   -----------   ----------    ---------
BALANCE AT DECEMBER 31, 1998..................  2,000,000    $20,000    1,048,000   $   215,600   $3,075,218    $(159,840)
                                                =========    =======    =========   ===========   ==========    =========

<CAPTION>
                                                                 UNREALIZED     DEFICIT
                                                                  LOSS ON     ACCUMULATED
                                                                 AVAILABLE-   DURING THE
                                                   TREASURY       FOR-SALE    DEVELOPMENT
                                                    STOCK        SECURITIES      STAGE
                                                --------------   ----------   -----------
<S>                                             <C>              <C>          <C>
Issuance of Common Stock in exchange for
contribution of available-for-sale securities
to capital, net of deferred taxes of
$1,138,616....................................
Unrealized loss on available-for-sale
  securities, net of deferred taxes of
  $427,951....................................                   $(641,777)
Net loss for the period from August 7, 1997
  (date of inception) to December 31, 1997....                                $  (253,771)
                                                                 ---------    -----------
BALANCE AT DECEMBER 31, 1997..................                    (641,777)      (253,771)
Change in unrealized loss.....................                     641,777
Contribution of available-for-sale securities
  to capital, net of deferred taxes of
  $300,000....................................
Contribution of cash..........................
Issuance of Common Stock in exchange for
  capital contributions.......................
Conversion of Common Stock into Series A
  Convertible Preferred Stock in 1998.........
Issuance of Series A Convertible Preferred
  Stock in 1998...............................
Issuance of Common Stock......................
Repurchase of Treasury Stock..................     $(12,933)
Net loss......................................                                 (3,670,173)
Collection of notes receivable from
  stockholders................................
                                                   --------      ---------    -----------
BALANCE AT DECEMBER 31, 1998..................     $(12,933)     $     -0-    $(3,923,944)
                                                   ========      =========    ===========
</TABLE>

See accompanying notes.

                                       F-5
<PAGE>   165

                           GENETIC MICROSYSTEMS, INC.

                            STATEMENTS OF CASH FLOWS

<TABLE>
<CAPTION>
                                                                               PERIOD FROM
                                                                             AUGUST 7, 1997
                                                            YEAR ENDED     (DATE OF INCEPTION)
                                                           DECEMBER 31,      TO DECEMBER 31,
                                                               1998               1997
                                                           ------------    -------------------
<S>                                                        <C>             <C>
OPERATING ACTIVITIES
Net loss.................................................  $(3,670,173)         $(253,771)
Adjustments to reconcile net loss to net cash used in
  operating activities:
  Depreciation and amortization..........................      103,198             13,918
  Deferred taxes.........................................   (1,268,616)          (170,000)
  Deferred rent..........................................       49,529
  Gain (loss) on sale of available-for-sale equity
     securities..........................................      664,505            (57,082)
  Changes in operating assets and liabilities:
     Prepaid expenses and other assets...................     (140,241)           (11,115)
     Accounts receivable.................................     (213,575)
     Inventories.........................................     (421,809)
     Accounts payable and accrued expenses...............      359,234            184,494
                                                           -----------          ---------
Net cash used in operating activities....................   (4,537,948)          (293,556)
INVESTING ACTIVITIES
Purchase of property and equipment.......................     (614,243)          (108,684)
Sale of available-for-sale equity securities.............    2,673,223            315,894
                                                           -----------          ---------
Net cash provided by investing activities................    2,058,980            207,210
FINANCING ACTIVITIES
Issuance of Series A and B Preferred Stock...............    3,877,851
Issuance of Common Stock purchase rights.................    3,000,000
Capital contribution.....................................       10,082
Issuance of Common Stock.................................        2,000
Purchase of Treasury Stock...............................         (333)
Collection of notes receivable from shareholders.........       41,160
Due to shareholder.......................................     (120,000)           120,000
                                                           -----------          ---------
Net cash provided by financing activities................    6,810,760            120,000
                                                           -----------          ---------
Increase in cash and cash equivalents....................    4,331,792             33,654
Cash and cash equivalents at beginning of period.........       33,654
                                                           -----------          ---------
Cash and cash equivalents at end of period...............  $ 4,365,446          $  33,654
                                                           ===========          =========
</TABLE>

See accompanying notes.

                                       F-6
<PAGE>   166

                           GENETIC MICROSYSTEMS, INC.

                         NOTES TO FINANCIAL STATEMENTS
                               DECEMBER 31, 1998

1. BASIS OF PRESENTATION

THE COMPANY

     Genetic MicroSystems, Inc. (the Company) was incorporated on August 7, 1997
to develop, manufacture and sell a new generation of enabling products for
genomics research and drug discovery. The Company was a development-stage
company until the commencement of substantial operations in 1998 and has
operated in a single segment since inception.

RISKS AND UNCERTAINTIES

     The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities, and
disclosure of contingent assets and liabilities, at the date of the financial
statements, and the reported amounts of revenues and expenses during the
reported period. Actual results could differ from those estimates.

2. SIGNIFICANT ACCOUNTING POLICIES

CASH EQUIVALENTS

     Cash equivalents consist of those highly liquid investments having
maturities of three months or less at the date of purchase. The carrying value
of cash equivalents approximates fair value.

CONCENTRATIONS OF CREDIT RISK

     Financial instruments that potentially subject the Company to a
concentration of credit risk consist primarily of cash and cash equivalents and
available-for-sale securities. The Company invests its excess cash primarily in
high-quality securities. Available-for-sale securities represented shares of
common stock of a publicly traded company contributed to the Company by the
founding shareholder. These securities were sold for cash by the Company based
on the working capital requirements of the Company.

AVAILABLE-FOR-SALE EQUITY SECURITIES

     The Company classifies its equity securities contributed by its founding
shareholder as available-for-sale, which are reported at fair value, in
accordance with Statement of Financial Accounting Standards (SFAS) No. 115,
Accounting for Certain Investments in Debt and Equity Securities. Under SFAS No.
115, unrealized holding gains and losses on available-for-sale securities are
excluded from income and reported as a separate component in shareholders'
equity, net of applicable taxes. Realized gains and losses from securities
classified as available-for-sale are included in income using the
specific-identification method for determining the cost of investments sold.

INVENTORIES

     Inventories, which consist of purchased components, units in process and
finished units, are valued at the lower of cost (first-in, first-out) or market.

                                       F-7
<PAGE>   167
                           GENETIC MICROSYSTEMS, INC.

                  NOTES TO FINANCIAL STATEMENTS -- (CONTINUED)

PROPERTY AND EQUIPMENT

     Property and equipment is recorded at cost. Provisions for depreciation and
amortization on property and equipment are computed using the straight-line
method over expected useful lives of the assets as follows:

<TABLE>
<CAPTION>
                                            ESTIMATED USEFUL LIFE
                                ---------------------------------------------
<S>                             <C>
Equipment                       3-5 years
Leasehold improvements          Term of the lease or useful life, whichever
                                is shorter.
</TABLE>

REVENUE RECOGNITION

     Product sales are recognized at the time finished units are shipped.
License revenue is recognized as earned based on the terms of the related
license agreement.

RESEARCH AND DEVELOPMENT

     Research and development costs are charged to operations as incurred.

LOSS PER SHARE

     Loss per share is presented in accordance with SFAS No. 128, Earnings Per
Share, which requires the disclosure of basic and diluted earnings (loss) per
share. Basic loss per share is based upon the Company's net loss divided by the
number of weighted shares outstanding during the reporting period. Diluted loss
per share for loss periods is the same as basic loss per share since the effect
of including the conversion of preferred stock and common stock equivalents of
warrants, options and other stock rights is anti-dilutive.

STOCK-BASED COMPENSATION

     As provided for under SFAS No. 123, Accounting for Stock Based
Compensation, the Company accounts for stock-based compensation for employees
based on the provisions of Accounting Principles Board Opinion No. 25,
Accounting for Stock Issued to Employees (APB No. 25). The Company discloses, as
required under SFAS No. 123, pro forma net loss in the notes to the financial
statements as if the measurement provisions of SFAS No. 123 had been adopted.

     The Company accounts for stock-based compensation to nonemployees based on
the provisions of SFAS No. 123.

RECENT ACCOUNTING PRONOUNCEMENT

     In 1998, the Company adopted SFAS No. 130, Reporting Comprehensive Income,
which requires presentation of a statement of comprehensive income that adjusts
net income (loss) and net income (loss) per share for changes in unrealized
gains and losses from available-for-sale securities. The adoption of this
Standard is reflected in the statements of operations and comprehensive loss for
each period presented.

                                       F-8
<PAGE>   168
                           GENETIC MICROSYSTEMS, INC.

                  NOTES TO FINANCIAL STATEMENTS -- (CONTINUED)

3. AVAILABLE-FOR-SALE EQUITY SECURITIES

     Information related to this balance at December 31, 1997 is as follows:

<TABLE>
<CAPTION>
                                                            MARKET       UNREALIZED
                                               COST         VALUE       HOLDING LOSS
                                            ----------    ----------    ------------
<S>                                         <C>           <C>           <C>
Equity securities.........................  $2,587,728    $1,518,000     $1,069,728
Deferred income tax benefit...............                                  427,951
                                                                         ----------
Net unrealized holding loss...............                               $  641,777
                                                                         ==========
</TABLE>

4. INVENTORIES

     Inventories consist of the following at December 31, 1998:

<TABLE>
<S>                                                           <C>
Purchased components........................................  $288,439
Units in process............................................   102,035
Finished units..............................................    31,335
                                                              --------
                                                              $421,809
                                                              ========
</TABLE>

5. PROPERTY AND EQUIPMENT

     Property and equipment consist of the following at December 31:

<TABLE>
<CAPTION>
                                                              1998        1997
                                                            --------    --------
<S>                                                         <C>         <C>
Equipment.................................................  $606,945    $102,465
Leasehold improvements....................................   115,982       6,219
                                                            --------    --------
                                                             722,927     108,684
Less accumulated depreciation and amortization............   117,116      13,918
                                                            --------    --------
                                                            $605,811    $ 94,766
                                                            ========    ========
</TABLE>

6. ACCRUED EXPENSES

     The balance consists of the following at December 31:

<TABLE>
<CAPTION>
                                                               1998       1997
                                                             --------    -------
<S>                                                          <C>         <C>
Accrued compensation and related taxes.....................  $164,575    $13,042
Other......................................................   126,584     33,300
                                                             --------    -------
                                                             $291,159    $46,342
                                                             ========    =======
</TABLE>

7. OPERATING LEASE

     The Company leases its present offices under an operating lease expiring in
2001. At December 31, 1998, future minimum lease payments amounted to $316,000
in 1999, $316,000 in

                                       F-9
<PAGE>   169
                           GENETIC MICROSYSTEMS, INC.

                  NOTES TO FINANCIAL STATEMENTS -- (CONTINUED)

2000 and $78,978 in 2001. Rent expense amounted to $230,000 in 1998 and $4,800
for the period from August 7, 1997 to December 31, 1997.

     The Company's lease contains certain rent inducements which are being
amortized over the term of the lease. The unamortized balance of the deferred
rent amounted to $49,529 at December 31, 1998.

8. COMMON STOCK PURCHASE RIGHTS

     In August 1998, the Company entered into an agreement with Takara Shuzo Co.
Ltd. (Takara), a distributor, which calls for the sale of microarray
manufacturing instruments and the sale of microarray manufacturing services
utilizing the Company's equipment, provided a 5% royalty is paid to the Company
for the sale of these services. The agreement also provides for the purchase,
subject to certain requirements, of the Company's shares by Takara through an
advance payment of $3.0 million, which has been included in the caption of
common stock purchase rights in the accompanying financial statements. The
number of shares issuable will be determined on August 19, 2003 (Closing) based
on the fair market value of the Company's stock at the time. Of the $3 million
advance, $2 million is repayable to Takara if certain milestones with respect to
the instrumentation have not been met.

     To the extent the two remaining milestone payments are returned to Takara
due to the Company's nonperformance, the Company is to issue Takara shares of
Common Stock equal to $1.0 million divided by the fair market value of the stock
at the Closing. In no event is the number of common shares issued to Takara to
exceed 10% of the total shares of outstanding Common Stock of the Company at the
time of the Closing. In the event that the Company's common stock issuable to
Takara is valued at less than $3.0 million or the amount not returned to Takara,
as described above, the Company will pay Takara the difference between the value
of the Company's common stock and $3.0 million or the amount not returned to
Takara.

     In connection with the agreement, the Company granted an employee warrants
to purchase 10% of the Common Stock ultimately issued to Takara at the fair
market value of the Common Stock on the date the shares are issued.

                                      F-10
<PAGE>   170
                           GENETIC MICROSYSTEMS, INC.

                  NOTES TO FINANCIAL STATEMENTS -- (CONTINUED)

9. INCOME TAXES

     Deferred income taxes consist of the following at December 31:

<TABLE>
<CAPTION>
                                                            1998         1997
                                                          ---------    ---------
<S>                                                       <C>          <C>
Deferred tax asset:
Net operating loss carryforwards........................  $ 120,000    $  56,535
  Start-up costs........................................    520,000       10,000
                                                          ---------    ---------
                                                            640,000       66,535
  Valuation allowance...................................   (640,000)
                                                          ---------    ---------
                                                                  0       66,535
Deferred tax liability:
  Book basis of available-for-sale equity securities in
     excess of tax basis................................                (607,200)
                                                          ---------    ---------
  Net deferred tax liability............................  $       0    $(540,665)
                                                          =========    =========
</TABLE>

     The income tax benefit of $1,268,166 in 1998 and $170,000 in 1997
represents the elimination of deferred tax liabilities recognized in connection
with the capital contributions described in Note 10, which are no longer payable
due to operating losses incurred by the Company in 1997 and 1998. At December
31, 1998, the Company had net operating loss carryforwards for income tax
reporting purposes of approximately $300,000 to offset future federal taxable
income, which begin to expire in 2012. A full valuation allowance has been
established due to the uncertainty of the realization of these benefits in
future years. In accordance with section 382 of the Internal Revenue Code, the
use of the above carryforward will be subject to annual limitations based upon
ownership changes of the Company's stock which have occurred.

10. SHAREHOLDERS' CAPITAL

COMMON STOCK

     The Company's founding shareholder contributed 150,000 shares of marketable
equity securities with a fair value (based on quoted market values) of $2.2
million, net of applicable taxes, to the Company in 1997 and 1998. These capital
contributions have been recorded net of applicable taxes since the tax basis of
the marketable equity securities contributed to the Company is nominal and the
Company is required to pay the applicable income taxes based on the fair value
of the investments when the investments are sold.

     In 1998, the Company sold 1,048,000 shares of restricted Common Stock to
certain employees in exchange for notes receivable due in 2003. The notes
receivable bear interest at the applicable minimum federal rate and are
collateralized by the shares of Common Stock.

PREFERRED STOCK

Series A Convertible Preferred Stock

     Each share of Series A Convertible Preferred Stock has the same number of
Common Stock votes as its conversion rights provide, as defined in the amended
Articles of Incorporation. Holders of Series A Convertible Preferred Stock have
preference over Common shareholders with respect to

                                      F-11
<PAGE>   171
                           GENETIC MICROSYSTEMS, INC.

                  NOTES TO FINANCIAL STATEMENTS -- (CONTINUED)

payment of dividends and distribution of assets in the event of liquidation.
Holders of Series A Convertible Preferred Stock are entitled to a liquidation
value of $2.00 per share, respectively, plus all declared and unpaid dividends
as of the liquidation date.

     Each share of Series A Convertible Preferred Stock is convertible at any
time into the number of shares of Common Stock which results from dividing the
conversion price per share in effect at the time of conversion into $2.00 per
share for each share of Series A Convertible Preferred Stock being converted and
automatically convert upon an initial public offering. The conversion price is
subject to adjustment for, among other things, stock splits, dividends and
recapitalizations, as defined in the Articles of Incorporation.

Series B Redeemable Convertible Preferred Stock

     Each share of Series B Redeemable Convertible Preferred Stock has the same
number of common stock votes as its conversion rights provide, as defined in the
amended Articles of Incorporation. Holders of Series B Redeemable Convertible
Preferred Stock have preference over holders of Series A Convertible Preferred
Stock who have preference over Common Stockholders with respect to payment of
dividends and distribution of assets in the event of liquidation. Holders of
Series A Convertible Preferred Stock are entitled to a liquidation value of
$8.50 per share, respectively, plus all declared and unpaid dividends as of the
liquidation date.

     Each share of Series B Redeemable Convertible Preferred Stock is
convertible at any time into the number of shares of Common Stock which results
from dividing the conversion price per share in effect at the time of conversion
into $8.50 per share for each share of Series A Convertible Preferred Stock
being converted and automatically convert upon an initial public offering. The
conversion price is subject to adjustment for, among other things, stock splits,
dividends and recapitalization, as defined in the Articles of Incorporation.

     The Company is required, at the option of the majority of Series B
Redeemable Convertible Preferred stockholders, to redeem one-third of the shares
on December 30, 2004, 2005 and 2006, respectively, at $8.50 per share plus all
declared and unpaid dividends.

Series A and B Preferred Stock Warrants

     In connection with the sale of Series A Preferred Stock, the Company issued
warrants to an employee and a vendor to purchase 50,000 and 4,000 shares,
respectively, of Series A Preferred Stock at $2.00 per share which expire in
2008. Additionally, in connection with the sale of Series B Preferred Stock, the
Company issued warrants to an employee to purchase 34,713 shares of Series B
Preferred Stock at $8.50 per share which expire in 2008.

     The Company has also entered into an agreement with an employee that
obligates the Company to issue options, at the same price as any new equity
raised up to $13.5 million, to preserve his percentage of the Company. In the
event this occurs, the Company intends to settle this obligation by issuing
additional options or making a cash payment. If no settlement agreement is
reached, the obligation will continue until the earlier of the date at which
$13.5 million is raised or December 31, 2004.

                                      F-12
<PAGE>   172
                           GENETIC MICROSYSTEMS, INC.

                  NOTES TO FINANCIAL STATEMENTS -- (CONTINUED)

STOCK OPTION PLAN

     The Company's Stock Plan allows for the granting of options to purchase
300,000 shares of Common Stock. Options generally vest over four years and
expire ten years from the grant date or 90 days from termination of employment,
whichever is sooner.

     Pro forma information regarding net loss was computed in accordance with
SFAS No. 123 and has been determined as if the Company accounted for its
employee stock options granted under the fair value methods of that Statement.
The fair value of these options was estimated at the date of grant using the
minimal value option pricing model with the following weighted-average
assumptions for 1998: risk-free interest rate of 5.4%, dividend yield of 0% and
a weighted-average expected life of the option of 4.0 years. The pro forma net
loss and net loss per share as computed under SFAS No. 123 for 1998 amounted to
$3,030,096 and $5.13 per share, respectively.

     The following table presents the option activity for the year ended
December 31, 1998:

<TABLE>
<CAPTION>
                                                                        WEIGHTED-
                                                                         AVERAGE
                                                                        EXERCISE
                                                              SHARES      PRICE
                                                              ------    ---------
<S>                                                           <C>       <C>
Outstanding at beginning of year............................       0
Granted.....................................................  60,000      $.34
                                                              ------      ----
Outstanding at end of year..................................  60,000      $.34
                                                              ======      ====
</TABLE>

     The weighted average per share fair value of options granted during 1998
was $.07.

     At December 31, 1998, there were 240,000 options available for grant under
the Plan. There were no options exercisable at December 31, 1998.

     The Company has reserved 3,021,066 shares of Common Stock at December 31,
1998 for conversion of Preferred Stock and exercise of options and warrants to
purchase Common Stock.

11. NONCASH FINANCING ACTIVITIES

     In 1998, 140,000 shares of Common Stock were issued in exchange for $10,082
of cash and $2,048,006 of available-for-sale securities previously contributed
to the Company. These shares, along with 10,000 shares of Common Stock, were
then converted into 1.5 million shares of Series A Convertible Preferred Stock.

                                      F-13
<PAGE>   173

                INTERIM UNAUDITED CONDENSED FINANCIAL STATEMENTS
                                  JULY 3, 1999

                           GENETIC MICROSYSTEMS, INC.

                                 BALANCE SHEET
                                  (UNAUDITED)

<TABLE>
<S>                                                           <C>
ASSETS
Current assets:
  Cash and cash equivalents.................................  $ 2,526,577
  Available for sale securities.............................           --
  Accounts receivable, net of allowance of $75,603 for
     doubtful accounts......................................    1,999,759
  Inventories...............................................      999,361
  Prepaid expenses and other assets.........................       70,561
                                                              -----------
Total current assets........................................    5,596,258
Property and equipment, net.................................      732,767
Deposits....................................................       64,000
                                                              -----------
                                                              $ 6,393,025
                                                              ===========
LIABILITIES AND SHAREHOLDERS' EQUITY
Current Liabilities:
  Accounts payable..........................................  $   773,280
  Accrued expenses..........................................      534,901
  Due to shareholder........................................           --
  Deferred revenue..........................................      543,837
                                                              -----------
Total current liabilities...................................    1,852,018
Deferred rent...............................................       38,099
Common stock purchase rights................................    3,000,000
Series B Redeemable Convertible Preferred Stock, $.01 par
  value; 582,353 shares authorized; 431,977 shares issued
  and outstanding (aggregate liquidation preference of
  $3,671,825 in 1999).......................................    3,671,825
Shareholders' equity (deficit):
  Series A Convertible Preferred Stock, $.01 par value;
     2,054,000 shares authorized; 2,000,000 shares issued
     and outstanding (aggregate liquidation preference of
     $4,000,000)............................................       20,000
  Common Stock, no par value; 5,000,000 shares authorized;
     1,054,499 shares issued................................      216,900
  Additional paid-in capital................................    3,063,216
  Notes receivable from shareholders........................     (159,391)
  Treasury Stock (47,797 shares of Common Stock), at cost...      (13,120)
  Accumulated deficit.......................................   (5,296,522)
                                                              -----------
TOTAL SHAREHOLDERS' EQUITY (DEFICIT)........................   (2,168,917)
                                                              -----------
                                                              $ 6,393,025
                                                              ===========
</TABLE>

                            See accompanying notes.

                                      F-14
<PAGE>   174

                           GENETIC MICROSYSTEMS, INC.

           CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                                FOR THE SIX MONTHS ENDED
                                                              -----------------------------
                                                              JULY 3, 1999    JUNE 30, 1998
                                                              ------------    -------------
<S>                                                           <C>             <C>
REVENUES
Net product Sales...........................................  $ 5,081,572      $        --
COSTS AND EXPENSES:
  Cost of sales.............................................    3,153,091               --
  Research and development..................................    1,381,309        1,070,532
  Selling, general and administrative.......................    1,984,137          705,615
                                                              -----------      -----------
                                                                6,518,537        1,776,147
                                                              -----------      -----------
LOSS FROM OPERATIONS........................................   (1,436,965)      (1,776,147)
OTHER INCOME (LOSS)
  Gain (loss) on sale of available for sale securities......           --         (664,505)
  Interest and dividend income, net.........................       64,387           17,975
                                                              -----------      -----------
                                                                   64,387         (646,530)
                                                              -----------      -----------
LOSS BEFORE INCOME TAX BENEFIT..............................   (1,372,578)      (2,422,677)
INCOME TAX BENEFIT..........................................           --          808,411
                                                              -----------      -----------
NET LOSS....................................................   (1,372,578)      (1,614,266)
CHANGE IN UNREALIZED LOSS ON AVAILABLE-FOR-SALE EQUITY
  SECURITIES................................................           --          641,777
                                                              -----------      -----------
COMPREHENSIVE NET LOSS......................................  $(1,372,578)     $  (972,489)
                                                              ===========      ===========
LOSS PER SHARE
NET LOSS PER SHARE -- BASIC AND DILUTED.....................  $     (1.36)     $    (10.35)
                                                              ===========      ===========
COMPREHENSIVE NET LOSS PER SHARE -- BASIC AND DILUTED.......  $     (1.36)     $     (6.24)
                                                              ===========      ===========
WEIGHTED AVERAGE COMMON SHARES -- BASIC AND DILUTED.........    1,009,499          155,901
                                                              ===========      ===========
</TABLE>

                            See accompanying notes.

                                      F-15
<PAGE>   175

                           GENETIC MICROSYSTEMS, INC.

                       CONDENSED STATEMENTS OF CASH FLOWS
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                                FOR THE SIX MONTHS ENDED
                                                              -----------------------------
                                                              JULY 3, 1999    JUNE 30, 1998
                                                              ------------    -------------
<S>                                                           <C>             <C>
OPERATING ACTIVITIES
Net loss....................................................  $(1,372,578)     $(1,614,266)
  Adjustments to reconcile net loss to net cash used in
     operating activities:
     Depreciation and amortization..........................      106,685           24,840
     Deferred taxes.........................................           --         (808,411)
     Deferred rent..........................................      (11,430)              --
     Gain (loss) on sale of available for sale equity
       securities...........................................           --          664,505
     Loss on the disposal of property and equipment.........        4,044               --
     Provision for doubtful accounts........................       75,603               --
  Changes in operating assets and liabilities:
     Prepaid expenses and other assets......................       16,795          (61,296)
     Accounts receivable....................................   (1,861,787)              --
     Inventories............................................     (577,552)              --
     Accounts payable and accrued expenses..................      764,453           73,825
     Deferred revenue.......................................      543,837               --
                                                              -----------      -----------
Net cash used in operating activities.......................   (2,311,930)      (1,720,803)
INVESTING ACTIVITIES
  Purchase of property and equipment........................     (237,685)        (282,958)
  Sale of available-for-sale equity securities..............           --        2,673,223
                                                              -----------      -----------
Net cash (used in) provided by investing activities.........     (237,685)       2,390,265
FINANCING ACTIVITIES
  Issuance of Series A and B Convertible Preferred Stock....      709,184          957,212
  Issuance of Common Stock..................................        1,300               --
  Purchase of Treasury Stock................................         (187)              --
  Collection of notes receivable............................          449               --
  Due to shareholder........................................           --         (120,000)
                                                              -----------      -----------
Net cash provided by financing activities...................      710,746          837,212
                                                              -----------      -----------
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS............   (1,838,869)       1,506,674
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD............    4,365,446           33,654
                                                              -----------      -----------
CASH AND CASH EQUIVALENTS AT END OF PERIOD..................  $ 2,526,577      $ 1,540,328
                                                              ===========      ===========
</TABLE>

                            See accompanying notes.

                                      F-16
<PAGE>   176

                           GENETIC MICROSYSTEMS, INC.

                    NOTES TO CONDENSED FINANCIAL STATEMENTS
                                  JULY 3, 1999
                                  (UNAUDITED)

1. BASIS OF PRESENTATION

THE COMPANY

     Genetic MicroSystems, Inc. (the "Company") was incorporated on August 7,
1997 to develop, manufacture and sell a new generation of enabling products for
genomics research and drug discovery. The Company was a development-stage
company until the commencement of substantial operations in 1998.

     The interim unaudited condensed financial statements have been prepared by
the Company pursuant to the rules and regulations of the Securities and Exchange
Commission and in accordance with generally accepted accounting principles.
Accordingly, certain information and footnote disclosures normally included in
annual financial statements have been omitted or condensed. In the opinion of
management, all necessary adjustments (consisting of only normal recurring
accruals) have been made to provide a fair presentation. The operating results
for the six months ended July 3, 1999 are not necessarily indicative of the
results that may be expected for the year ended December 31, 1999. Effective
January 1, 1999, for quarterly interim reporting, the company adopted a fiscal
quarter ending on the Saturday nearest to the end of the calendar quarter with
the exception of year end, which ends on December 31.

2. INVENTORIES

     Inventories at July 3, 1999 consist of the following at:

<TABLE>
<S>                                                           <C>
Purchased components........................................    $640,128
Units in process............................................     209,300
Finished units..............................................      34,945
Demonstration inventory.....................................     114,988
                                                                --------
                                                                $999,361
                                                                ========
</TABLE>

3. INCOME TAXES

     Deferred income taxes consist of the following at July 3, 1999:

<TABLE>
<S>                                                           <C>
Deferred tax asset:
Net operating loss and tax credits carry-forwards...........   $  850,000
  Start-up costs............................................      480,000
                                                               ----------
                                                                1,330,000
  Valuation allowance.......................................    1,330,000
                                                               ----------
                                                               $        0
                                                               ==========
</TABLE>

     The income tax benefit of $808,411 in 1998 represents the elimination of
deferred tax liabilities recognized in connection with capital contributions,
which are no longer payable due to the operating losses incurred by the Company
in 1997 and 1998. At July 3, 1999, the Company had net operating loss
carryforwards for income tax reporting purposes of approximately $1,400,000, to
offset future

                                      F-17
<PAGE>   177
                           GENETIC MICROSYSTEMS, INC.

             NOTES TO CONDENSED FINANCIAL STATEMENTS -- (CONTINUED)
                                  JULY 3, 1999
                                  (UNAUDITED)

federal taxable income which begin to expire in 2012. At July 3, 1999, the
Company had tax credit carryforwards for income tax purposes of approximately
$310,000 to offset future federal taxable income which begin to expire in 2012.
A full valuation allowance has been established due to the uncertainty of the
realization of these benefits in future years. In accordance with section 382 of
Internal Revenue Code, the use of the above carry forward will be subject to
annual limitations based upon ownership changes of the Company's stock which
have occurred.

4. SERIES B REDEEMABLE CONVERTIBLE PREFERRED STOCK

     The Company closed its second round of sales of the Series B Redeemable
Convertible Preferred Stock in January 1999, selling an additional 84,845 shares
for net proceeds of $721,186.

     Each share of Series B Redeemable Convertible Preferred Stock has the same
number of common stock votes as its conversion rights provide, as defined in the
amended Articles of Incorporation. Holders of Series B Redeemable Convertible
Preferred Stock have preference over Series A Convertible Preferred Stock who
have preference over common stock shareholders with respect to payment of
dividends and distribution of assets in event of liquidation. Holders of Series
A Convertible Preferred Stock are entitled to a liquidation value of $8.50 per
share, respectively, plus all declared and unpaid dividends as of the
liquidation date.

     Each share of Series B Redeemable Convertible Preferred Stock is
convertible at any time into the number of shares of common stock which results
from dividing the conversion price per share in effect at the time of conversion
into $8.50 per share for each share of Series B Redeemable Convertible Preferred
Stock being converted. Each share of Series B Redeemable Convertible Preferred
Stock will automatically convert upon an initial public offering. The conversion
price is subject to adjustment for, among other things, stock splits, dividends
and recaptalizations, as defined in the Articles of Incorporation.

     The Company is required, at the option of the majority of Series B
Redeemable Convertible Preferred Stock stockholders, to redeem one-third of the
shares on December 30, 2004, 2005, and 2006, respectively, at $8.50 per share
plus all declared and unpaid dividends.

SERIES B PREFERRED STOCK WARRANTS

     The Company issued additional warrants to an employee to purchase 33,485
shares of Series B Preferred Stock at $8.50 per share which expire in 2008. No
value has been assigned to these warrants.

5. SUBSEQUENT EVENTS:

     The Company has entered into an Agreement and Plan of Merger dated
September 10, 1999 with Affymetrix Corporation of Santa Clara, California. The
agreement is subject to the satisfaction of certain closing conditions, among
which are a Hart-Scott-Rodino filing and an effective Form S-4 Registration
Statement.

                                      F-18
<PAGE>   178

                                    PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 20.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

     As permitted by Section 102(b)(7) of the Delaware General Corporation Law,
Affymetrix' charter includes a provision that eliminates the personal liability
of a director to Affymetrix or its stockholders for monetary damages arising out
of the director's breach of his or her fiduciary duty. The charter provides,
however, that unless otherwise permitted by applicable law, a director remains
potentially liable for monetary damages for:

     - breach of the director's duty of loyalty to Affymetrix or its
       stockholders;

     - acts or omissions not in good faith or which involve misconduct or a
       knowing violation of law;

     - an improper payment of a dividend or an improper redemption or repurchase
       of Affymetrix' stock (as provided in Section 174 of the Delaware General
       Corporation Law); or

     - any transaction from which a director derives an improper personal
       benefit.

Any repeal or modification of this provision will not affect any right or
protection of a director that exists at the time of such repeal or modification.

     Section 145 of the Delaware General Corporation Law empowers a Delaware
corporation to indemnify any persons who are, or are threatened to be made,
parties to any threatened, pending or completed legal action, suit or
proceeding, whether civil, criminal, administrative or investigative (other than
an action by or in the right of such corporation) by reason of the fact that
such person is or was an officer, director, employee or agent of such
corporation, or is or was serving at the request of such corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise. The indemnity may include expenses
(including attorneys' fees), judgments, fines and amounts paid in settlement
actually and reasonably incurred by such person in connection with such action,
suit or proceeding, provided that such officer, director, employee or agent
acted in good faith and in a manner he or she reasonably believed to be in or
not opposed to the corporation's best interests, and, for criminal proceedings,
had no reasonable cause to believe his or her conduct was unlawful. A Delaware
corporation may indemnify officers and directors in an action by or in the right
of the corporation under the same conditions, except that no indemnification is
permitted without judicial approval if the officer or director is adjudged to be
liable to the corporation. Where an officer or director is successful on the
merits or otherwise in the defense of any action referred to above, the
corporation must indemnify him or her against the expenses which such officer or
director actually and reasonably incurred.

     Article VIII of the bylaws of Affymetrix provides in terms similar to those
of Section 145 of the Delaware General Corporation Law that Affymetrix has the
power and is required to indemnify its directors and officers in accordance with
Delaware Law.

     The right to indemnification includes the right to be paid by Affymetrix
the expenses (including attorneys' fees) incurred in defending any suits brought
in advance of their final disposition; provided, however, that if the Delaware
General Corporation Law requires, an advancement of expenses incurred by an
indemnitee in his or her capacity as a director or officer (and not in any other
capacity in which service was or is rendered by the indemnitee, including,
without limitation, service to an employee benefit plan) will be made only upon
delivery to Affymetrix of an undertaking, by or on behalf of the indemnitee, to
repay all amounts so advanced if it will ultimately be determined by final
judicial decision from which there is no further right to appeal. The rights to
indemnification

                                      II-1
<PAGE>   179

and to the advancement of expenses covered in Sections 1 and 2 of Article VII of
Affymetrix' bylaws are contract rights and these rights continue as to an
indemnitee who has ceased to be a director or officer and will inure to the
benefit of his or her heirs, executors and administrators.

     If a claim covered by Affymetrix' bylaws (Article VIII, Sections 1 and 2)
is not paid in full by Affymetrix within 60 days after a written claim has been
received by Affymetrix, except in the case of advancement of expenses pursuant
to the terms of an undertaking, in which case the applicable period is 20 days,
an indemnitee will be entitled to be paid also the expense of prosecuting or
defending the suit. The failure of the indemnitee to meet any applicable
standard for indemnification set forth in the Delaware General Corporation Law:

     - is a defense in any suit brought by the indemnitee to enforce a right to
       indemnification (but not in a suit brought by the indemnitee to enforce a
       right to an advancement of expenses), and

     - entitles Affymetrix to recover an advancement of expenses pursuant to the
       terms of an undertaking upon a final adjudication in any suit brought by
       Affymetrix to recover an advancement of expenses pursuant to the terms of
       an undertaking.

Neither the failure of Affymetrix, including its board of directors, independent
legal counsel, or its stockholders, to have made a determination prior to the
commencement of the suit that indemnification of the indemnitee is proper in the
circumstances because the indemnitee has met the applicable standard of conduct
set forth in the Delaware General Corporation Law, nor an actual determination
by Affymetrix, including its board of directors, independent legal counsel, or
its stockholders, that the indemnitee has not met the applicable standard of
conduct or, in the case of such a suit brought by the indemnitee, is a defense
to the suit. In any suit brought by an indemnitee to enforce a right to
indemnification or to an advancement of expenses, or brought by Affymetrix to
recover an advancement of expenses pursuant to the terms of an undertaking, the
burden of proving that the indemnitee is not entitled to an advancement of
expenses under Article VIII of the bylaws or otherwise will be on Affymetrix.

     The rights to indemnification and to the advancement of expenses conferred
in Affymetrix' bylaws are not exclusive of any other right which any person may
have or acquire under Affymetrix' charter, any statute, agreement, vote of
stockholders or disinterested directors or otherwise.

     Affymetrix may maintain insurance, at its expense, to protect itself and
any director, officer, employee or agent of Affymetrix or another corporation,
partnership, joint venture, trust or other enterprise against any expense,
liability or loss, whether or not Affymetrix would have the power to indemnify
that person against the expense, liability, or loss under the Delaware General
Corporation Law.

     Affymetrix may, to the extent authorized from time to time by the board of
directors, grant rights to indemnification and to the advancement of expenses to
any officer, employee or agent of Affymetrix to the fullest extent of the
provisions allowed by its bylaws with respect to the indemnification and
advancement of expenses of directors and officers of Affymetrix.

                                      II-2
<PAGE>   180

ITEM 21.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.

     (a) The following Exhibits are filed herewith unless otherwise indicated:


<TABLE>
<CAPTION>
EXHIBIT
  NO.                             DESCRIPTION
- -------                           -----------
<C>       <S>
  2.1     Agreement and Plan of Merger, dated as of September 10,
          1999, among Affymetrix, Inc., GMS Acquisition, Inc., Genetic
          MicroSystems, Inc., Jean Montagu and the stockholders set
          forth on the signature pages thereto (attached as Appendix A
          to the Proxy Statement/ Prospectus contained in this
          Registration Statement).
  3.1     Amended and Restated Certificate of Incorporation of
          Affymetrix, Inc. (incorporated by reference to Exhibit 3.1
          of Affymetrix' Registration Statement on Form S-3 as filed
          July 12, 1999).
  3.2     Bylaws of Affymetrix, Inc. (incorporated by reference to
          Appendix C of Affymetrix' Definitive Proxy Statement on
          Schedule 14A as filed on April 29, 1998).
  4.1     Rights Agreement dated as of October 15, 1998 between
          Affymetrix, Inc. and America Stock Transfer & Trust Company,
          as Rights Agent (incorporated by reference to Exhibit 1 of
          Affymetrix' Form 8-A as filed on October 16, 1998).
  4.2     Indenture dated as of September 22, 1999, between
          Affymetrix, Inc. and The Bank of New York, as Trustee.*
  5.1     Opinion of Vern Norviel, Senior Vice President, General
          Counsel and Corporate Secretary of Affymetrix, Inc.,
          regarding the validity of the shares of Affymetrix, Inc.
          Common Stock to be registered under this Registration
          Statement.*
  8.1     Opinion of Sullivan & Cromwell regarding certain United
          States federal income tax consequences of the Merger.*
  8.2     Opinion of Palmer & Dodge LLP regarding certain United
          States federal income tax consequences of the Merger.*
 10.1     Stock Option Agreement, dated as of September 10, 1999,
          between Affymetrix, Inc. and Genetic MicroSystems, Inc.
          (attached as Appendix B to the Proxy Statement/Prospectus
          contained in this Registration Statement).
 23.1     Consent of Ernst & Young LLP, Independent Auditors (Boston,
          Massachusetts).
 23.2     Consent of Ernst & Young LLP, Independent Auditors (Palo
          Alto, California).
 23.3     Consent of Vern Norviel, Senior Vice President, General
          Counsel & Corporate Secretary (contained in Exhibit 5.1).*
 23.4     Consent of Sullivan & Cromwell (contained in Exhibit 8.1).*
 23.5     Consent of Palmer & Dodge LLP (contained in Exhibit 8.2).*
 24.1     Power of Attorney*
 99.1     Form of Proxy for holders of Genetic MicroSystems, Inc.
          Common Stock, Genetic MicroSystems, Inc. Series A
          Convertible Preferred Stock, and Series B Convertible
          Preferred Stock Genetic MicroSystems, Inc.
 99.2     Escrow Agreement, dated as of September 10, 1999, among
          Genetic MicroSystems, Inc., Affymetrix, Inc., GMS
          Acquisition, Inc., Jean Montagu, as Stockholder
          Representative, and Bank One Trust Company, N.A., as Escrow
          Agent (attached as Appendix C to the Proxy
          Statement/Prospectus contained in this Registration
          Statement).
 99.3     Form of Stockholder Voting Agreement entered into by
          Affymetrix and Jean Montagu, Dominic Montagu, Sasha Montagu,
          Stanley Rose, Peter Honkanen and Myles L. Mace, Jr.
          (attached as Appendix D to the Proxy Statement/Prospectus
          contained in this Registration Statement).
</TABLE>


- ---------------

 * Previously filed.


                                      II-3
<PAGE>   181

     (b) Financial Data Schedule.

     Schedules are omitted because they either are not required or are not
applicable or because equivalent information has been included in the financial
statements, the notes thereto or elsewhere herein.

ITEM 22.  UNDERTAKINGS.

     (a) The undersigned registrant hereby undertakes:

        (1) to file, during any period in which offers or sales are being made,
            a post-effective amendment to this registration statement:

           (i)  To include any prospectus required by Section 10(a)(3) of the
                Securities Act of 1933;

           (ii)  To reflect in the prospectus any facts or events arising after
                 the effective date of the registration statement (or the most
                 recent post-effective amendment thereof) which, individually or
                 in the aggregate, represent a fundamental change in the
                 information set forth in the registration statement.
                 Notwithstanding the foregoing, any increase or decrease in
                 volume of securities offered (if the total dollar value of
                 securities offered would not exceed that which was registered)
                 and any deviation from the low or high end of the estimated
                 maximum offering range may be reflected in the form of
                 prospectus filed with the Commission pursuant to Rule 424(b)
                 if, in the aggregate, the changes in volume and price represent
                 no more than 20 percent change in the maximum aggregate
                 offering price set forth in the "Calculation of Registration
                 Fee" table in the effective registration statement; and

           (iii) To include any material information with respect to the plan of
                 distribution not previously disclosed in the registration
                 statement or any material change to such information in the
                 registration statement.

        (2) that, for the purpose of determining any liability under the
            Securities Act of 1933, each such post-effective amendment shall be
            deemed to be a new registration statement relating to the securities
            offered therein, and the offering of such securities at that time
            shall be deemed to be the initial bona fide offering thereof.

        (3) to remove from registration by means of a post-effective amendment
            any of the securities being registered which remain unsold at the
            termination of the offering.

     (b) The undersigned registrant hereby undertakes that, for purposes of
         determining any liability under the Securities Act of 1933, each filing
         of the registrant's annual report pursuant to Section 13(a) or 15(d) of
         the Securities Exchange Act of 1934 (and, where applicable, each filing
         of an employee benefit plan's annual report pursuant to Section 15(d)
         of the Exchange Act) that is incorporated by reference in the
         registration statement shall be deemed to be a new registration
         statement relating to the securities offered therein, and the offering
         of such securities at that time shall be deemed to be the initial bona
         fide offering thereof.

     (c) (1) The undersigned registrant hereby undertakes as follows: that prior
             to any public reoffering of the securities registered hereunder
             through use of a prospectus which is a part of this registration
             statement, by any person or party who is deemed to be an
             underwriter within the meaning of Rule 145(c), the issuer
             undertakes that such reoffering prospectus will contain the
             information called for by this form with respect to

                                      II-4
<PAGE>   182

             reofferings by persons who may be deemed underwriters, in addition
             to the information called for by the other Items of this form; and

        (2) the registrant undertakes that every prospectus (i) that is filed
            pursuant to paragraph (1) immediately preceding, or (ii) that
            purports to meet the requirements of Section 10(a)(3) of the
            Securities Act and is used in connection with an offering of
            securities subject to Rule 415, will be filed as a part of an
            amendment to this registration statement and will not be used until
            such amendment is effective, and that, for purposes of determining
            any liability under the Securities Act, each such post-effective
            amendment shall be deemed to be a new registration statement
            relating to the securities offered therein, and the offering of such
            securities at that time shall be deemed to be the initial bona fide
            offering thereof.

     (d) Insofar as indemnification for liabilities arising under the Securities
         Act of 1933 may be permitted to directors, officers and controlling
         persons of the registrant pursuant to the foregoing provisions, or
         otherwise, the registrant has been advised that in the opinion of the
         Securities and Exchange Commission such indemnification is against
         public policy as expressed in the Securities Act and is, therefore,
         unenforceable. In the event that a claim for indemnification against
         such liabilities (other than the payment by the registrant of expenses
         incurred or paid by a director, officer or controlling person of the
         registrant in the successful defense of any action, suit or proceeding)
         is asserted by such director, officer, or controlling person in
         connection with the securities being registered, the registrant will,
         unless in the opinion of its counsel the matter has been settled by
         controlling precedent, submit to a court of appropriate jurisdiction
         the question whether such indemnification by it is against public
         policy as expressed in the Securities Act and will be governed by the
         final adjudication of such issue.

     (e) The undersigned registrant hereby undertakes to respond to requests for
         information that is incorporated by reference into the prospectus
         pursuant to items 4, 10(b), 11 or 13 of this form, within one business
         day of receipt of such request, and to send the incorporated documents
         by first class mail or other equally prompt means. This includes
         information contained in documents filed subsequent to the effective
         date of the registration statement through the date of responding to
         the request.

     (f) The undersigned registrant hereby undertakes to supply by means of a
         post-effective amendment all information concerning a transaction, and
         the company being acquired involved therein, that was not the subject
         of and included in this registration statement when it became
         effective.

                                      II-5
<PAGE>   183

                                   SIGNATURES


     Pursuant to the requirements of the Securities Act of 1933, as amended,
Affymetrix, Inc. has duly caused this registration statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Santa
Clara, State of California, on November 16, 1999.


                                          AFFYMETRIX, INC.

                                          By: /s/ VERN NORVIEL
                                            ------------------------------------
                                              Name: Vern Norviel
                                              Title:   Senior Vice President,
                                                       General Counsel &
                                                       Corporate Secretary

     Pursuant to the requirements of the Securities Act of 1933, as amended,
this registration statement has been signed by the following persons in the
capacities and on the dates indicated.


<TABLE>
<CAPTION>
                     SIGNATURE                                   TITLE                     DATE
                     ---------                                   -----                     ----

<C>                                                  <S>                             <C>
                         *                           Chief Executive Officer and     November 16, 1999
- ---------------------------------------------------    Chairman of the Board
             Stephen P.A. Fodor, Ph.D.

                         *                           Vice President and Chief        November 16, 1999
- ---------------------------------------------------    Financial Officer (Principal
                 Edward M. Hurwitz                     Financial and Accounting
                                                       Officer)

                         *                           Vice Chairman of the Board      November 16, 1999
- ---------------------------------------------------
              John D. Diekman, Ph.D.

                         *                           Director                        November 16, 1999
- ---------------------------------------------------
                 Paul Berg, Ph.D.

                         *                           Director                        November 16, 1999
- ---------------------------------------------------
               Vernon R. Loucks, Jr.

                         *                           Director                        November 16, 1999
- ---------------------------------------------------
               Barry C. Ross, Ph.D.

                         *                           Director                        November 16, 1999
- ---------------------------------------------------
                  David B. Singer

                         *                           Director                        November 16, 1999
- ---------------------------------------------------
                Lubert Stryer, M.D.

                         *                           Director                        November 16, 1999
- ---------------------------------------------------
                   John A. Young

*By Power of Attorney

                 /s/ VERN NORVIEL                    Attorney-in-Fact
- ---------------------------------------------------
                   Vern Norviel
</TABLE>


                                      II-6
<PAGE>   184

                                 EXHIBIT INDEX


<TABLE>
<CAPTION>
EXHIBIT
  NO.                             DESCRIPTION
- -------                           -----------
<C>       <S>
  2.1     Agreement and Plan of Merger, dated as of September 10,
          1999, among Affymetrix, Inc., GMS Acquisition, Inc., Genetic
          MicroSystems, Inc., Jean Montagu and the stockholders set
          forth on the signature pages thereto (attached as Appendix A
          to the Proxy Statement/ Prospectus contained in this
          Registration Statement).
  3.1     Amended and Restated Certificate of Incorporation of
          Affymetrix, Inc. (incorporated by reference to Appendix B of
          Affymetrix' Definitive Proxy Statement on Schedule 14A as
          filed April 29, 1998).
  3.2     Bylaws of Affymetrix, Inc. (incorporated by reference to
          Appendix C of Affymetrix' Definitive Proxy Statement on
          Schedule 14A as filed on April 29, 1998).
  4.1     Rights Agreement dated as of October 15, 1998 between
          Affymetrix, Inc. and America Stock Transfer & Trust Company,
          as Rights Agent (incorporated by reference to Exhibit 1 of
          Affymetrix' Form 8-A as filed on October 16, 1998).
  4.2     Indenture dated as of September 22, 1999, between
          Affymetrix, Inc. and The Bank of New York, as Trustee.*
  5.1     Opinion of Vern Norviel, Senior Vice President, General
          Counsel and Corporate Secretary of Affymetrix, Inc.,
          regarding the validity of the shares of Affymetrix, Inc.
          Common Stock to be registered under this Registration
          Statement.*
  8.1     Opinion of Sullivan & Cromwell regarding certain United
          States federal income tax consequences of the Merger.*
  8.2     Opinion of Palmer & Dodge LLP regarding certain United
          States federal income tax consequences of the Merger.*
 10.1     Stock Option Agreement, dated as of September 10, 1999,
          between Affymetrix, Inc. and Genetic MicroSystems, Inc.
          (attached as Appendix B to the Proxy Statement/Prospectus
          contained in this Registration Statement).
 23.1     Consent of Ernst & Young LLP, Independent Auditors (Boston,
          Massachusetts).
 23.2     Consent of Ernst & Young LLP, Independent Auditors (Palo
          Alto, California).
 23.3     Consent of Vern Norviel, Senior Vice President, General
          Counsel and Corporate Secretary (contained in Exhibit 5.1).*
 23.4     Consent of Sullivan & Cromwell (contained in Exhibit 8.1).*
 23.5     Consent of Palmer & Dodge LLP (contained in Exhibit 8.2).*
 24.1     Power of Attorney*
 99.1     Form of Proxy for holders of Genetic MicroSystems, Inc.
          Common Stock, Genetic MicroSystems, Inc. Series A
          Convertible Preferred Stock, and Series B Convertible
          Preferred Stock Genetic MicroSystems, Inc.
 99.2     Escrow Agreement, dated as of September 10, 1999, among
          Genetic MicroSystems, Inc., Affymetrix, Inc., GMS
          Acquisition, Inc., Jean Montagu, as Stockholder
          Representative, and Bank One Trust Company, N.A., as Escrow
          Agent (attached as Appendix C to the Proxy
          Statement/Prospectus contained in this Registration
          Statement).
 99.3     Form of Stockholder Voting Agreement entered into by
          Affymetrix and Jean Montagu, Dominic Montagu, Sasha Montagu,
          Stanley Rose, Peter Honkanen and Myles L. Mace, Jr.
          (attached as Appendix D to the Proxy Statement/Prospectus
          contained in this Registration Statement).
</TABLE>


                                ---------------

 * Previously filed.


<PAGE>   1
                                                                    Exhibit 23.1




               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS


         We consent to the reference to our firm under the caption "Experts" and
to the use of our report dated January 12, 1999, included in the Proxy Statement
of Genetic MicroSystems, Inc., that is made a part of the Registration Statement
(Form S-4) and related Prospectus of Affymetrix, Inc. for the registration of
shares of its common stock.



/s/ ERNST & YOUNG LLP



Boston, Massachusetts
October 14, 1999




<PAGE>   1
                                                                    EXHIBIT 23.2


               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS


We consent to the reference to our firm under the caption "Experts" in the proxy
statement of Genetic MicroSystems, Inc. that is made part of the registration
statement on Form S-4 and prospectus of Affymetrix, Inc. and to the
incorporation by reference therein of our report dated January 29, 1999 except
for Note 11, as to which the date is March 25, 1999, with respect to the
financial statements and schedule of Affymetrix, Inc. included in its Annual
Report (Form 10-K) for the year ended December 31, 1998, filed with the
Securities and Exchange Commission.


                                                           /s/ Ernst & Young LLP


Palo Alto, California
October 13, 1999


<PAGE>   1
                                                                    EXHIBIT 99.1


                           GENETIC MICROSYSTEMS, INC.
                                 34 COMMERCE WAY
                           WOBURN, MASSACHUSETTS 01801

           THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

         The undersigned hereby appoints _______________ and _______________,
and each of them, with full power of substitution, as proxies to represent and
to vote, as specified below, all the shares of stock of Genetic MicroSystems,
Inc., held of record by the undersigned on __________ __, 1999, at the Special
Meeting of Stockholders to be held on __________ __, 1999 and at any
adjournments, postponements, continuations or reschedulings thereof. The
undersigned hereby revokes any previous proxies with respect to the matters
covered in this proxy.

         THIS PROXY, WHEN PROPERLY EXECUTED, WILL BE VOTED IN THE MANNER
SPECIFIED ON THE REVERSE SIDE. IF THIS CARD IS PROPERLY EXECUTED BUT NO VOTE IS
SPECIFIED, THIS PROXY WILL BE VOTED FOR ADOPTION OF THE MERGER AGREEMENT.

                           (continued on reverse side)


            You can vote by completing, signing, dating and returning
            the enclosed proxy card in the enclosed stamped envelope.
<PAGE>   2
Please mark your vote as indicated in this example:  /X/


<TABLE>
<S>    <C>                                                                             <C>             <C>
1.     To adopt and approve the Agreement and Plan of
       Merger, dated as of September 10, 1999, by and among
       Affymetrix, Inc., a Delaware corporation, GMS
       Acquisition, Inc., a Massachusetts corporation wholly
       owned by Affymetrix, Genetic MicroSystems, Inc., a
       Massachusetts corporation,  Jean Montagu as
       stockholder representative and the stockholders of
       Genetic Microsystems, Inc. listed in the signature pages
       thereto                                                                        [  ] FOR        [  ] AGAINST

2.     Vote on the proposal that the merger does not constitute a liquidation,
       dissolution or winding up of Genetic Microsystems, Inc. (only holders of
       shares of Genetic Microsystems Series A Convertible Preferred
       Stock are eligible to vote on this proposal)                                    [  ] FOR        [  ] AGAINST

3.     To appoint Jean Montagu as stockholder representative to act on behalf of
       the shareholders of Genetic MicroSystems in connection with the merger          [  ] FOR        [  ] AGAINST

4.     In their discretion, the proxies are authorized to vote upon such other
       business as may properly come before the meeting or any adjournments,
       postponements, continuations or reschedulings thereof.
</TABLE>


       CHECK HERE IF YOU PLAN TO ATTEND THE SPECIAL MEETING:  [   ]

       Dated:
       ---------------, 1999

       -------------------------------
       Signature (including title, if any)

       -------------------------------
       Signature if held jointly

       Please sign your name above exactly as it appears hereon. Joint owners
       should each sign. When signing as attorney, executor, administrator,
       trustee or guardian, please give full title as such. If a corporation,
       please sign in full corporate name by president or authorized officer. If
       a partnership, please sign in partnership name by authorized person.





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