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                                                                EXHIBIT 10.28


TO:                         Richard P. Shea

FROM:                       Taylor J. Crouch

DATE:                       December 13, 2001

SUBJECT:                    FIRST AMENDMENT TO EMPLOYMENT OFFER LETTER

         We hereby agree that your Employment Offer Letter, dated December
23, 1998 and comprised of the Offer Letter, the Terms & Conditions Agreement,
and the Inventions and Non-Disclosure Agreement (collectively the "Offer
Letter"), be and hereby is amended effective December 13, 2001, as provided
for herein. Except as specifically modified herein, the terms of the Offer
Letter, and all other agreements, exhibits and other instruments related
thereto or to your employment with Variagenics, Inc. (including any of its
successors or assigns, the "Company") shall remain in full force and effect.
This first amendment to your Employment Agreement shall be referred to herein
as the "Amendment."

         Effective December 13, 2001, your Employment Agreement is amended as
follows:

1.       Paragraph 2 of the Terms & Conditions section of the Offer Letter is
         revised by adding the following at the end thereto:

            "Notwithstanding the foregoing, if your employment with the Company
            is terminated by the Company at any time without "cause," you shall,
            upon execution of a general release of claims with respect to the
            Company, its officers, directors, employees and agents, receive
            six (6) months of salary continuation at your then current base
            salary, payable in accordance with the Company's customary payroll
            practices. `Base salary' for these purposes is base compensation
            paid to you without regard to payment of any bonuses or other forms
            of compensation."

2.       The Terms & Conditions section of the Offer Letter is further revised
         by adding the following as a new Paragraph 10 to the end thereof:

         "10.     Vesting on a Change in Control.

         (a)  Upon the effective date of a Change in Control, 50% of the then
              outstanding unvested options to purchase shares of common stock of
              the Company held by you as of such date (whether granted to you
              prior to or after execution of this Amendment) shall be
              immediately vested and shall be otherwise exercisable in
              accordance with the terms of the stock option agreement pursuant
              to which they were granted. The remaining 50% of the then
              outstanding unvested options shall vest monthly in six equal
              installments beginning with the first day of the month following
              the effective date of the Change in Control; provided that, all
              then remaining outstanding unvested options shall immediately 100%
              vest if you are terminated by the Company without Cause after the
              effective date of the Change in Control but prior to the end of
              the six month period following such Change in Control.


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         (b)  CHANGE IN CONTROL DEFINED. A `Change in Control' shall be deemed
              to have occurred if (i) there is a sale or transfer of all or
              substantially all of the assets of the Company in one or a series
              of transactions; (ii) any `person,' as such term is used in
              Section 13(d) of the Securities Exchange Act of 1934, as amended
              (or any successor provision) (the `Exchange Act'), together with
              all `affiliates' and `associates' (as such terms are defined in
              Rule 12b-2 under the Exchange Act or any successor provision) of
              such person, shall become the `beneficial owner' or `beneficial
              owners' (as defined in Rules 13d-3 and 13d-5 under the Exchange
              Act or any successor provision), directly or indirectly, of
              securities of the Company representing in the aggregate thirty
              percent (30%) or more of either (1) the then outstanding shares of
              common stock of the Company or (2) the combined voting power of
              all then outstanding securities of the Company having the right
              under ordinary circumstances to vote in an election of the Board
              of Directors of the Company (hereafter referred to as an
              `Acquisition'); PROVIDED, that, notwithstanding the foregoing, an
              Acquisition shall not be deemed to have occurred for purposes of
              this clause (ii) solely as the result of an acquisition of
              securities by the Company which, by reducing the number of shares
              of common stock or other voting securities outstanding, increases
              (x) the proportionate number of shares of common stock
              beneficially owned by any person to thirty percent (30%) or more
              of the common stock then outstanding or (y) the proportionate
              voting power represented by the voting securities beneficially
              owned by any person to thirty percent (30%) or more of the
              combined voting power of all then outstanding voting securities;
              or (iii) there is a merger or consolidation between the Company
              and an entity other than a subsidiary of the Company in which the
              Company is not the continuing or surviving corporation and
              pursuant to which the holders of the Company's voting stock
              immediately prior to such merger or consolidation would not be the
              holders immediately after such merger or consolidation of at least
              50% of the voting stock of the continuing or surviving
              corporation.

         (c)  All agreements between you and the Company governing the grant to
              you of stock options shall be and hereby are amended to the extent
              necessary to effectuate the provisions of this Agreement. You
              acknowledge that the acceleration of Incentive Stock Options
              ("ISOs") granted pursuant to section 422 of the Internal Revenue
              Code (the "Code") may cause certain of those options to fail to
              satisfy section 422(d) of the Code, which may result in less
              favorable individual tax treatment on such option. You understand
              and acknowledge such result and agree to the conversion, as
              necessary, of ISOs to non-qualified stock options as a
              precondition to the acceleration of the option grant described
              herein. ISOs with the least difference between exercise price and
              fair market value on the date of the conversion shall be converted
              to non-qualified options first. In all other respects all such
              agreements between you and the Company shall remain in full force
              and effect, and shall be administered in accordance with their
              terms.

         (d)  Notwithstanding anything provided herein, if you are considered to
              be a `disqualified individual' (as defined in Section 280G of the
              Code), and the acceleration of vesting of options together with
              any other payments which you have a right to receive from the
              Company (or its affiliates and subsidiaries) in the event of a
              Change in Control


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             (collectively the "Severance Compensation"), would constitute a
             "parachute payment" (as defined in Section 280G(b)(2) of the Code),
             the Severance Compensation shall be reduced. The reduction shall
             be in an amount so that the present value of the total amount
             received by you from the Company will be one dollar ($1.00) less
             than three (3) times the Base Amount (as defined in Section 280G
             of the Code) so that no portion of the amounts received by you
             shall be subject to the excise tax imposed by Section 4999 of the
             Code (excise tax).

             The determination as to whether any reduction in Severance
             Compensation is necessary and the amount of any such reduction
             shall be made by the Company's independent public accountants (the
             "Accounting Firm") which shall provide detailed supporting
             calculations both to the Company and to you within fifteen (15)
             business days of the date payment is made. Any such determination
             by the Accounting Firm shall be conclusive and binding upon you
             and the Company. You shall determine which part of the Severance
             Compensation shall be eliminated or reduced consistent with the
             requirements of this section and you will notify the Company
             promptly in writing; PROVIDED, that if you do not make such a
             determination within ten (10) business days of the receipt of the
             calculations made by the Accounting Firm, the Company shall
             determine which part of the Severance Compensation shall be
             eliminated or reduced consistent with the requirements of this
             section and shall notify you promptly in writing of such election.

             If through error or otherwise you should receive payments under
             this Agreement, together with other payments you have the right to
             receive from the Company, in excess of one dollar ($1.00) less
             than three times your Base Amount, you shall immediately repay the
             excess to the Company upon notification that an overpayment has
             been made."

         It is understood and agreed that this Amendment shall constitute a
binding agreement upon execution by both parties, and represents (along with
the Offer Letter) the entire agreement and understanding between us with
respect to the subject matter contained herein. If the terms of this
Amendment are acceptable to you, please sign where indicated below. This
Amendment is executed as an instrument under seal as of the date indicated
below.


                                       VARIAGENICS, INC.


                                       By: /s/ Taylor J. Crouch
                                          --------------------------------
                                          Taylor J. Crouch

Acknowledged and Agreed:


/s/ Richard P. Shea
----------------------------------
Richard P. Shea


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