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                                                                   EXHIBIT 10.24

September 5, 2001

Joseph S. Mohr
47 Beach Plum Lane
Scituate, MA 02066

Dear Jay,

I am pleased to confirm our offer of employment for the position of Vice
President, Business Development & Marketing, initially reporting to Taylor J.
Crouch, President & CEO. Your start date will be on or around October 1, 2001.

Your gross biweekly base salary will be nine thousand thirty-eight and 47/100
(9,038.47) dollars which if annualized equals two hundred thirty-five thousand
and no/100 (235,000.00).

        a. You will be offered a Stock Option Agreement entitling you to
           purchase one hundred thousand (100,000) shares of Common Stock of
           Variagenics, Inc., subject to the approval of the Company's Board of
           Directors. Your right to exercise these options will vest 12/48 of
           the amount 12 months after your full-time starting date and 1/48 of
           the amount vesting monthly thereafter for thirty-six (36) months.

        b. You will receive a sign-on bonus in the net amount of $20,000 which
           is payable ninety (90) days after your date of hire. The amount of
           this bonus is a net amount, i.e. after deduction of any applicable
           taxes at statutory rates.

        c. You will be eligible for a performance based bonus of up to thirty
           (30) percent of your base salary. These bonuses are typically payable
           at the end of the calendar year. For calendar year 2001, you will
           receive a minimum of thirty-five thousand two hundred fifty and
           no/100 (35,250.00) dollars.

        d. Your employment status is as an "Employee at Will", which means that
           you or the Company may terminate your employment at any time and for
           any reason. In the event your employment is terminated by the Company
           "without cause", your base salary will be continued for a maximum of
           six (6) months.

        e. The Company may from time to time authorize bonuses comprising cash
           and/or additional stock options based on your annual

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           performance review, review of team performance and the Company's
           overall financial condition.

As an employee, you are entitled to receive such benefits as are generally
provided to Variagenics' employees in accordance with plan documents and
policies in effect from time to time. The Company reserves the right to change,
add or cease any particular benefit without notice at its sole discretion.
During your first week of employment you will be provided with details on the
benefits programs available to you. A summary overview of the benefits has been
provided to you.

As part of this offer, you will be required to sign an "Invention and
Non-Disclosure Agreement" as well as a Non-Compete and Non-Solicitation which
are attached to this letter.

Of course, no provision of this letter shall be construed to create an express
or implied employment contract for a specific period of time. Either you or the
Company may terminate the employment relationship at any time for any reason
with or without notice.

On your first day, please plan on arriving by 9:00 a.m. and ask for Human
Resources. In keeping with federal regulations, we require proof of your
eligibility to work in the United States. Please find enclosed a list of
acceptable documents or forms of identification.

This offer of employment will expire on Friday, September 14, 2001, unless
accepted by you prior to such date.

Jay, I look forward to welcoming you to our team. If you have any questions,
please feel free to contact me at 617 588 5315.

Sincerely yours,

/s/ Mary A. McWeeney

Mary A. McWeeney
Senior Director, Human Resources

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                                VARIAGENICS, INC.

                     INVENTION AND NON-DISCLOSURE AGREEMENT

This agreement is made between VARIAGENICS, INC., a Delaware corporation
(hereinafter referred to collectively with its subsidiaries as the "Company"),
and Joseph S. Mohr (the "Employee"). In consideration of the employment or the
continued employment of the Employee by the Company, the Company and the
Employee agree as follows:

1.      PROPRIETARY INFORMATION

(a)     The Employee agrees that all information, whether or not in writing, of
        a private, secret or confidential nature concerning the Company's
        business, business relationships or financial affairs (collectively,
        "Proprietary Information") is and shall be the exclusive property of the
        Company. By way of illustration, but not limitation, Proprietary
        Information may include inventions, products, processes, methods,
        techniques, formulas, compositions, compounds, projects, developments,
        plans, research data, clinical data, financial data, personnel data,
        computer programs, customer and supplier lists, and contacts at or
        knowledge of customers or prospective customers of the Company. The
        Employee will not disclose any Proprietary Information to any person or
        entity other than employees of the Company or use the same for any
        purposes (other than in the performance of his/her duties as an employee
        of the Company) without written approval by an officer of the Company,
        either during or after his/her employment with the Company, unless and
        until such Proprietary Information has become public knowledge without
        fault by the Employee.

(b)     The Employee agrees that all files, letters, memoranda, reports,
        records, data, sketches, drawings, laboratory notebooks, program
        listings, or other written, photographic, or other tangible material
        containing Proprietary Information, whether created by the Employee or
        others, which shall come into his/her custody or possession, shall be
        and are the exclusive property of the Company to be used by the Employee
        only in the performance of his/her duties for the Company. All such
        materials or copies thereof and all tangible property of the Company in
        the custody or possession of the Employee shall be delivered to the
        Company, upon the earlier of (1) a request by the Company or (2)
        termination of his/her employment. After such delivery, the Employee
        shall not retain any such materials or copies thereof or any such
        tangible property.

(c)     The Employee agrees that his/her obligation not to disclose or to use
        information and materials of the types set forth in paragraphs (a) and
        (b) above and his/her obligation to return materials and tangible
        property, set forth in paragraph (b) above also extends to such types of
        information, materials and tangible property of customers of the Company
        or suppliers to the Company or other third parties who may have
        disclosed or entrusted the same to the Company or to the Employee.

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2.      DEVELOPMENTS

(a)     The Employee will make full and prompt disclosure to the Company of all
        inventions, improvements, discoveries, methods, developments, software
        and works of authorship whether patentable or not, which are created,
        made, conceived or reduced to practice by him/her or under his/her
        direction or jointly with others during his/her employment by the
        Company, whether or not during normal working hours or on the premises
        of the Company (all of which are collectively referred to in this
        Agreement as "Developments").

(b)     The Employee agrees to assign and does hereby assign to the Company (or
        any person or entity designated by the Company) all his/her right, title
        and interest in and to all Developments and all related patents, patent
        applications, copyrights and copyright applications. However, this
        paragraph 2(b) shall not apply to Developments which do not relate to
        the present or planned business or research and development of the
        Company and which are made and conceived by the Employee not during
        normal working hours, not on the Company's premises and not using the
        Company's tools, devices, equipment or Proprietary Information. The
        Employee understands that, to the extent this Agreement shall be
        construed in accordance with the laws of any state which precludes a
        requirement in an employee agreement to assign certain classes of
        inventions made by an employee, this paragraph 2(b) shall be interpreted
        not to apply to any inventions which a court rules and/or the Company
        agrees falls within such classes. The Employee also hereby waives all
        claims to moral rights in any Developments.

(c)     The Employee agrees to cooperate fully with the Company, both during and
        after his/her employment with the Company, with respect to the
        procurement, maintenance and enforcement of copyrights, patents and
        other intellectual property rights (both in the United States and
        foreign countries) relating to Developments. The Employee shall sign all
        papers, including, without limitation, copyright applications, patent
        applications, declarations, oaths, formal assignments, assignments of
        priority rights, and powers of attorney, which the Company may deem
        necessary or desirable in order to protect its rights and interests in
        any Development. The Employee further agrees that if the Company is
        unable, after reasonable effort, to secure the signature of the Employee
        on any such papers, any executive officer of the Company shall be
        entitled to execute any such papers as the agent and the attorney in
        fact of the Employee, and the Employee hereby irrevocably designates and
        appoints each executive officer of the Company as his/her agent and
        attorney in fact to execute any such papers on his/her behalf, and to
        take any and all actions as the Company may deem necessary or desirable
        in order to protect its rights and interests in any Development, under
        the conditions described in this sentence.

3.      OTHER AGREEMENTS

        The Employee hereby represents that, except as the Employee has
        disclosed in Exhibit 1 to this Agreement or in writing to the Company,
        the Employee is not bound by the terms of any agreement with any
        previous employer or other party to refrain from using or disclosing any
        trade secret or confidential or proprietary

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        information in the course of his/her employment with the Company or to
        refrain from competing directly or indirectly, with the business of such
        previous employer or any other party, or which would restrict his/her
        ability to accept employment or perform work for the Company. The
        Employee further represents that his/her performance of all terms of
        this Agreement and as an employee of the Company does not and will not
        breach any agreement to keep in confidence proprietary information,
        knowledge or data acquired by the Employee in confidence or in trust
        prior to his/her employment with the Company, and the Employee will not
        disclose to the Company or induce the Company to use any confidential or
        proprietary information or material belonging to any previous employer
        or others.

4.      UNITED STATES GOVERNMENT OBLIGATIONS

        The Employee acknowledges that the Company from time to time may have
        agreements with other persons or with the United States Government, or
        agencies thereof, which impose obligations or restrictions on the
        Company regarding inventions made during the course of work under such
        agreements or regarding the confidential nature of such work. The
        Employee agrees to be bound by all such obligations and restrictions
        which are made known to the Employee and to take all action necessary to
        discharge the obligations of the Company under such agreements.

5.      EMPLOYMENT STATUS

        The Employee understands that this Agreement does not constitute a
        contract of employment and does not imply that his/her employment will
        continue for any period of time.

6.      MISCELLANEOUS

(a)     The invalidity or unenforceability of any provision of this Agreement
        shall not affect the validity or enforceablility of any other provision
        of this Agreement.

(b)     This Agreement supersedes all prior agreements, written or oral, between
        the Employee and the Company relating to the subject matter of this
        Agreement. This Agreement may not be modified, changed or discharged in
        whole or in part, except by an agreement in writing signed by the
        Employee and the Company. The Employee agrees that any change or changes
        in his/her duties, salary or compensation after signing of this
        Agreement shall not affect the validity or the scope of this Agreement.

(c)     This Agreement will be binding upon the Employee's heirs, executors, and
        administrators and will inure to the benefit of the Company and its
        successors and assigns.

(d)     No delay or omission by the Company in exercising any right under this
        Agreement will operate as a waiver of that or any other right. A waiver
        or consent given by the Company on any one occasion is effective only in
        that instance and will not be construed as a bar to or waiver of any
        right on any occasion.

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(e)     The Employee expressly consents to be bound by the provisions of this
        Agreement for the benefit of the Company or any subsidiary or affiliate
        thereof to whose employ the Employee may be transferred without the
        necessity that this Agreement be re-signed at the time of such transfer.

(f)     The restrictions contained in this Agreement are necessary for the
        protection of the business and goodwill of the Company and are
        considered by the Employee to be reasonable for such purpose. The
        Employee agrees that any breach of this Agreement is likely to cause the
        Company substantial and irrevocable damage and therefore, in the event
        of any such breach, the Employee agrees that the Company, in addition to
        such other remedies which may be available, shall be entitled to
        specific performance and other injunctive relief.

(g)     This Agreement is governed by and will be construed as a sealed
        instrument under and in accordance with the laws of the Commonwealth of
        Massachusetts. Any action, suit, or other legal proceeding which is
        commenced to resolve any matter arising under or relating to any
        provision of this Agreement shall be commenced only in a court of the
        Commonwealth of Massachusetts (or, if appropriate, a federal court
        located within Massachusetts), and the Company and the Employee each
        consents to the jurisdiction of such a court.

         THE EMPLOYEE ACKNOWLEDGES THAT HE/SHE HAS CAREFULLY READ THIS
         AGREEMENT AND UNDERSTANDS AND AGREES TO ALL OF THE PROVISIONS
                               IN THIS AGREEMENT.

WITNESS:

VARIAGENICS, INC.

Date:  9/5/01                           By:  /s/ Mary A. McWeeney
      -----------------                     ------------------------------------
                                              Mary A. McWeeney
                                              Senior Director, Human Resources

BY EMPLOYEE:

Date:  9/9/01                           By:  /s/ Joseph S. Mohr
      -----------------                     ------------------------------------
                                             Joseph S. Mohr

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                                VARIAGENICS, INC.

                                    EXHIBIT 1

                     INVENTION AND NON-DISCLOSURE AGREEMENT

                                OTHER AGREEMENTS

Pursuant to section 3 of this Agreement, the following is a list of pertinent
agreements between the Employee and previous employers or other parties:

                                    None

                                    As shown below (please list)


BY VARIAGENICS, INC.:                  BY EMPLOYEE:


 /s/ Mary A. McWeeney                   /s/ Joseph S. Mohr
-----------------------------------    -----------------------------------------
Mary A. McWeeney                       Joseph S. Mohr


Dated:  9/5/01                         Dated:   9/9/01
       ------------------                      ------------------

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                                    EXHIBIT A
                   NON COMPETE AND NON SOLICITATION AGREEMENT

This Agreement becomes an integral part of the Employee Terms and Conditions
signed on 9/9/2001.

            (a)  During the Employment Period (and for a period of six months
after the termination or expiration thereof), the Employee will not directly or
indirectly:

                 (i)  as an individual proprietor, partner, stockholder,
        officer, employee, director, joint venturer, investor, lender, or in any
        other capacity whatsoever (other than as the holder of not more than
        three percent (3%) of the total outstanding stock of a publicly held
        company), engage in the business of developing, producing, marketing or
        selling discovery, clinical and/or commercial stage pharmacogenomics
        products of the kind or type developed or being developed, produced,
        marketed or sold by the Company (collectively, "Competing Activity").

            (b)  During the Employment Period (and for a period of one year
after the termination or expiration thereof), the Employee will not directly or
indirectly:

                 (i)  recruit, solicit or induce, or attempt to induce, any
        employee or employees of the Company to terminate their employment with,
        or otherwise cease their relationship with, the Company; or

                 (ii) solicit, divert or take away, or attempt to divert or to
        take away, the business or patronage of any of the clients, customers or
        accounts, or prospective clients, customers or accounts, of the Company
        which were contacted, solicited or served by the Employee while employed
        by the Company.

            (c)  If any restriction set forth in this Section is found by any
court of competent jurisdiction to be unenforceable because it extends for too
long a period of time or over too great a range of activities or in too broad a
geographic area, it shall be interpreted to extend only over the maximum period
of time, range of activities or geographic area as to which it may be
enforceable.

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            (d)  The restrictions contained in this Section are necessary for
the protection of the business and goodwill of the Company and are considered by
the Employee to be reasonable for such purpose. The Employee agrees that any
breach of this Section will cause the Company substantial and irrevocable damage
and therefore, in the event of any such breach, in addition to such other
remedies which may be available, the Company shall have the right to seek
specific performance and injunctive relief.

                          ACCEPTED


                           /s/ Mary A. McWeeney                9/5/01
                          ---------------------------------   ------------------
                          VARIAGENICS, INC.                   Date


                           /s/ Joseph S. Mohr                  9/9/01
                          ---------------------------------   ------------------
                          Joseph S. Mohr                      Date