Document:

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                                                                   EXHIBIT 10.38

                          TRANSKARYOTIC THERAPIES, INC.

         Amendment to Amended and Restated 1993 Long-Term Incentive Plan

              Approved by the Board of Directors on June 30, 2004

1.    Section 7.2(f) of the Amended and Restated 1993 Long-Term Incentive Plan
      is deleted in its entirety and the following section is inserted in lieu
      thereof:

            "7.2 (f) Transferability. Except as the Committee may otherwise
            determine or provide in an Award, Awards shall not be sold,
            assigned, pledged or otherwise encumbered by the person to whom they
            are granted, either voluntarily or by operation of law, except by
            will or the laws of descent and distribution or, other than in the
            case of an Incentive Option, pursuant to a qualified domestic
            relations order, and during the life of the Participant, shall be
            exercisable only by the Participant. References to a Participant, to
            the extent relevant in the context, shall include references to
            authorized transferees."

2.    Section 13.2 of the Amended and Restated 1993 Long-Term Incentive Plan is
      deleted in its entirety and the following section is inserted in lieu
      thereof:

            "13.2 Reorganization and Change in Control Events.

                  (1)   Definitions

                        (a)   A "Reorganization Event" shall mean:

                             (i)    any merger or consolidation of the Company
                                    with or into another entity as a result of
                                    which all the Common Stock of the Company is
                                    converted into or exchanged for the right to
                                    receive cash, securities or other property
                                    or is cancelled; or

                             (ii)   any exchange of all of the Common Stock of
                                    the Company for cash, securities or other
                                    property pursuant to a share exchange
                                    transaction.

                        (b)   A "Change in Control Event" shall mean:

                             (i)    the acquisition by an individual, entity or
                                    group (within the meaning of Section
                                    13(d)(3) or 14(d)(2) of the Securities
                                    Exchange Act of 1934, as amended (the
                                    "Exchange Act")) (a "Person"), of beneficial

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                                    ownership (within the meaning of Rule 13d-3
                                    promulgated under the Exchange Act) of any
                                    capital stock of the Company if, after such
                                    acquisition, such Person would beneficially
                                    own 50% or more of the combined voting power
                                    of the then-outstanding securities of the
                                    Company entitled to vote generally in the
                                    election of directors (the "Outstanding
                                    Company Voting Securities"); provided,
                                    however, that for purposes of this
                                    subsection (i), the following acquisitions
                                    shall not constitute a Change in Control:

                                   (A)     any acquisition directly from the
                                           Company (excluding an acquisition
                                           pursuant to the exercise, conversion
                                           or exchange of any security
                                           exercisable for, convertible into or
                                           exchangeable for common stock or
                                           voting securities of the Company,
                                           unless the Person exercising,
                                           converting or exchanging such
                                           security acquired such security
                                           directly from the Company or an
                                           underwriter or agent of the Company),

                                   (B)     any acquisition by any employee
                                           benefit plan (or related trust)
                                           sponsored or maintained by the
                                           Company or any corporation controlled
                                           by the Company, or

                                   (C)     any acquisition by any corporation
                                           pursuant to a Business Combination
                                           (as defined below) which complies
                                           with clauses (A) and (B) of
                                           subsection (iii) of this definition;
                                           or

                             (ii)   such time as the Continuing Directors (as
                                    defined below) do not constitute a majority
                                    of the Board (or, if applicable, the Board
                                    of Directors of a successor corporation to
                                    the Company), where the term "Continuing
                                    Director" means at any date a member of the
                                    Board (A) who was a member of the Board as
                                    of June 30, 2004 or (B) who was nominated or
                                    elected subsequent to such date by at least
                                    a majority of the directors who were
                                    Continuing Directors at the time of such
                                    nomination or election or whose election to
                                    the Board was recommended or endorsed by at
                                    least a majority of the directors who were
                                    Continuing Directors at the time of such
                                    nomination or election; provided, however,
                                    that

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                                    there shall be excluded from this clause (B)
                                    any individual whose initial assumption of
                                    office occurred as a result of an actual or
                                    threatened election contest with respect to
                                    the election or removal of directors or
                                    other actual or threatened solicitation of
                                    proxies or consents, by or on behalf of a
                                    person other than the Board; or

                             (iii)  the consummation of a merger, consolidation,
                                    reorganization, recapitalization or share
                                    exchange involving the Company or a sale or
                                    other disposition of all or substantially
                                    all of the assets of the Company (a
                                    "Business Combination"), unless, immediately
                                    following such Business Combination, each of
                                    the following two conditions is satisfied:

                                   (A)     all or substantially all of the
                                           individuals and entities who were the
                                           beneficial owners of the Outstanding
                                           Company Voting Securities immediately
                                           prior to such Business Combination
                                           beneficially own, directly or
                                           indirectly, more than 50% of the
                                           combined voting power of the
                                           then-outstanding securities entitled
                                           to vote generally in the election of
                                           directors of the resulting or
                                           acquiring corporation in such
                                           Business Combination (which shall
                                           include, without limitation, a
                                           corporation which as a result of such
                                           transaction owns the Company or
                                           substantially all of the Company's
                                           assets either directly or through one
                                           or more subsidiaries) (such resulting
                                           or acquiring corporation is referred
                                           to herein as the "Acquiring
                                           Corporation") in substantially the
                                           same proportions as their ownership
                                           of the Outstanding Company Voting
                                           Securities immediately prior to such
                                           Business Combination, and

                                   (B)     no Person (excluding any employee
                                           benefit plan (or related trust)
                                           maintained or sponsored by the
                                           Company or by the Acquiring
                                           Corporation) beneficially owns,
                                           directly or indirectly, 50% or more
                                           of the combined voting power of the
                                           then-outstanding securities of such
                                           corporation entitled to vote
                                           generally in the election of

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                                           directors (except to the extent that
                                           such ownership existed prior to the
                                           Business Combination).

                        (c)   "Good Reason" shall mean any significant
                              diminution in the Participant's title, authority,
                              or responsibilities from and after the occurrence
                              of a Reorganization Event or Change in Control
                              Event, as the case may be, or any reduction in the
                              annual cash compensation payable to the
                              Participant from and after such Reorganization
                              Event or Change in Control Event, as the case may
                              be, or the relocation of the place of business at
                              which the Participant is principally located to a
                              location that is greater than 50 miles from its
                              location immediately prior to such Reorganization
                              Event or Change in Control Event.

                        (d)   "Cause" shall mean any (i) willful failure by the
                              Participant, which failure is not cured within 30
                              days of written notice to the Participant from the
                              Company, to perform his or her material
                              responsibilities to the Company or (ii) willful
                              misconduct by the Participant which affects the
                              business reputation of the Company.

                  (2)   Effect on Options

                        (a)   Reorganization Event. Upon the occurrence of a
                              Reorganization Event (regardless of whether such
                              event also constitutes a Change in Control Event),
                              or the execution by the Company of any agreement
                              with respect to a Reorganization Event (regardless
                              of whether such event will result in a Change in
                              Control Event), the Commitee shall provide that
                              all outstanding Options shall be assumed, or
                              equivalent options shall be substituted, by the
                              acquiring or succeeding corporation (or an
                              affiliate thereof); provided that if such
                              Reorganization Event also constitutes a Change in
                              Control Event, except to the extent specifically
                              provided to the contrary in the instrument
                              evidencing any Option or any other agreement
                              between a Participant and the Company, such
                              assumed or substituted options shall become
                              immediately exercisable in full if, on or prior to
                              the date 18 months after the date on which the
                              Reorganization Event is consummated, the
                              Participant's employment with the Company or the
                              acquiring or succeeding corporation is terminated
                              for Good Reason by the Participant or is
                              terminated without Cause by the Company or the
                              acquiring or succeeding corporation. For purposes
                              hereof, an Option shall be considered to be

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                              assumed if, following consummation of the
                              Reorganization Event, the Option confers the right
                              to purchase, for each share of Common Stock
                              subject to the Option immediately prior to the
                              consummation of the Reorganization Event, the
                              consideration (whether cash, securities or other
                              property) received as a result of the
                              Reorganization Event by holders of Common Stock
                              for each share of Common Stock held immediately
                              prior to the consummation of the Reorganization
                              Event (and if holders were offered a choice of
                              consideration, the type of consideration chosen by
                              the holders of a majority of the outstanding
                              shares of Common Stock); provided, however, that
                              if the consideration received as a result of the
                              Reorganization Event is not solely common stock of
                              the acquiring or succeeding corporation (or an
                              affiliate thereof), the Company may, with the
                              consent of the acquiring or succeeding
                              corporation, provide for the consideration to be
                              received upon the exercise of Options to consist
                              solely of common stock of the acquiring or
                              succeeding corporation (or an affiliate thereof)
                              equivalent in fair market value to the per share
                              consideration received by holders of outstanding
                              shares of Common Stock as a result of the
                              Reorganization Event.

                                     Notwithstanding the foregoing, if the
                              acquiring or succeeding corporation (or an
                              affiliate thereof) does not agree to assume, or
                              substitute for, such Options, the Committee shall,
                              upon written notice to the Participants, provide
                              that all then unexercised Options will become
                              exercisable in full as of a specified time prior
                              to the Reorganization Event and will terminate
                              immediately prior to the consummation of such
                              Reorganization Event, except to the extent
                              exercised by the Participants before the
                              consummation of such Reorganization Event, which
                              period of exercisability shall not be less than 20
                              days or more than 60 days; provided, however, that
                              in the event of a Reorganization Event under the
                              terms of which holders of Common Stock will
                              receive upon consummation thereof a cash payment
                              for each share of Common Stock surrendered
                              pursuant to such Reorganization Event (the
                              "Acquisition Price"), then the Committee may
                              instead provide that all outstanding Options shall
                              terminate upon consummation of such Reorganization
                              Event and that each Participant shall receive, in
                              exchange therefor, a cash payment equal to the
                              amount, if any, by which (A) the Acquisition Price
                              multiplied by the number of shares of Common Stock
                              subject to such outstanding Options (whether or
                              not then

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                              exercisable), exceeds (B) the aggregate exercise
                              price of such Options.

                        (b)     Change in Control Event that is not a
                                Reorganization Event. Upon the occurrence of a
                                Change in Control Event that does not also
                                constitute a Reorganization Event, except to the
                                extent specifically provided to the contrary in
                                the instrument evidencing any Option or any
                                other agreement between a Participant and the
                                Company, each such Option shall become
                                immediately exercisable in full if, on or prior
                                to the date 18 months after the date on which
                                the Change in Control Event is consummated, the
                                Participant's employment with the Company or the
                                acquiring or succeeding corporation is
                                terminated for Good Reason by the Participant or
                                is terminated without Cause by the Company or
                                the acquiring or succeeding corporation.

                  (3)   Effect on Restricted Stock Award

                        (a)   Reorganization Event that is not a Change in
                              Control Event. Upon the occurrence of a
                              Reorganization Event that is not a Change in
                              Control Event, the repurchase and other rights of
                              the Company under each outstanding Restricted
                              Stock Award shall inure to the benefit of the
                              Company's successor and shall apply to the cash,
                              securities or other property which the Common
                              Stock was converted into or exchanged for pursuant
                              to such Reorganization Event in the same manner
                              and to the same extent as they applied to the
                              Common Stock subject to such Restricted Stock
                              Award.

                        (b)   Change in Control Event. Upon the occurrence of a
                              Change in Control Event (regardless of whether
                              such event also constitutes a Reorganization
                              Event), except to the extent specifically provided
                              to the contrary in the instrument evidencing any
                              Restricted Stock Award or any other agreement
                              between a Participant and the Company, each such
                              Restricted Stock Award shall immediately become
                              free from all conditions or restrictions if, on or
                              prior to the date 18 months after the date on
                              which the Change of Control Event is consummated,
                              the Participant's employment with the Company or
                              the acquiring or succeeding corporation is
                              terminated for Good Reason by the Participant or
                              is terminated without Cause by the Company or the
                              acquiring or succeeding corporation.<PAGE>

                                                                   EXHIBIT 10.39

                          TRANSKARYOTIC THERAPIES, INC.

    Amendment to 2001 Non-Officer, Non-Director Employee Stock Incentive Plan

              Approved by the Board of Directors on June 30, 2004

1. Section 7(c) of the 2001 Non-Officer, Non-Director Employee Stock Incentive
Plan is deleted in its entirety and the following section is inserted in lieu
thereof:

      "7(c) Reorganization and Change in Control Events.

            (1)   Definitions

                  (a)   A "Reorganization Event" shall mean:

                        (i)   any merger or consolidation of the Company with or
                              into another entity as a result of which all the
                              Common Stock of the Company is converted into or
                              exchanged for the right to receive cash,
                              securities or other property or is cancelled; or

                        (ii)  any exchange of all of the Common Stock of the
                              Company for cash, securities or other property
                              pursuant to a share exchange transaction.

                  (b)   A "Change in Control Event" shall mean:

                        (i)   the acquisition by an individual, entity or group
                              (within the meaning of Section 13(d)(3) or
                              14(d)(2) of the Securities Exchange Act of 1934,
                              as amended (the "Exchange Act")) (a "Person"), of
                              beneficial ownership (within the meaning of Rule
                              13d-3 promulgated under the Exchange Act) of any
                              capital stock of the Company if, after such
                              acquisition, such Person would beneficially own
                              50% or more of the combined voting power of the
                              then-outstanding securities of the Company
                              entitled to vote generally in the election of
                              directors (the "Outstanding Company Voting
                              Securities"); provided, however, that for purposes
                              of this subsection (i), the following acquisitions
                              shall not constitute a Change in Control:

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                              (A)  any acquisition directly from the Company
                                   (excluding an acquisition pursuant to the
                                   exercise, conversion or exchange of any
                                   security exercisable for, convertible into or
                                   exchangeable for common stock or voting
                                   securities of the Company, unless the Person
                                   exercising, converting or exchanging such
                                   security acquired such security directly from
                                   the Company or an underwriter or agent of the
                                   Company),

                              (B)  any acquisition by any employee benefit plan
                                   (or related trust) sponsored or maintained by
                                   the Company or any corporation controlled by
                                   the Company, or

                              (C)  any acquisition by any corporation pursuant
                                   to a Business Combination (as defined below)
                                   which complies with clauses (A) and (B) of
                                   subsection (iii) of this definition; or

                        (ii)  such time as the Continuing Directors (as defined
                              below) do not constitute a majority of the Board
                              (or, if applicable, the Board of Directors of a
                              successor corporation to the Company), where the
                              term "Continuing Director" means at any date a
                              member of the Board (A) who was a member of the
                              Board as of June 30, 2004 or (B) who was nominated
                              or elected subsequent to such date by at least a
                              majority of the directors who were Continuing
                              Directors at the time of such nomination or
                              election or whose election to the Board was
                              recommended or endorsed by at least a majority of
                              the directors who were Continuing Directors at the
                              time of such nomination or election; provided,
                              however, that there shall be excluded from this
                              clause (B) any individual whose initial assumption
                              of office occurred as a result of an actual or
                              threatened election contest with respect to the
                              election or removal of directors or other actual
                              or threatened solicitation of proxies or consents,
                              by or on behalf of a person other than the Board;
                              or

                        (iii) the consummation of a merger, consolidation,
                              reorganization, recapitalization or share exchange
                              involving the Company or a sale or other
                              disposition of all or substantially all of the
                              assets of

<PAGE>

                              the Company (a "Business Combination"), unless,
                              immediately following such Business Combination,
                              each of the following two conditions is satisfied:

                              (A)  all or substantially all of the individuals
                                   and entities who were the beneficial owners
                                   of the Outstanding Company Voting Securities
                                   immediately prior to such Business
                                   Combination beneficially own, directly or
                                   indirectly, more than 50% of the combined
                                   voting power of the then-outstanding
                                   securities entitled to vote generally in the
                                   election of directors of the resulting or
                                   acquiring corporation in such Business
                                   Combination (which shall include, without
                                   limitation, a corporation which as a result
                                   of such transaction owns the Company or
                                   substantially all of the Company's assets
                                   either directly or through one or more
                                   subsidiaries) (such resulting or acquiring
                                   corporation is referred to herein as the
                                   "Acquiring Corporation") in substantially the
                                   same proportions as their ownership of the
                                   Outstanding Company Voting Securities
                                   immediately prior to such Business
                                   Combination, and

                              (B)  no Person (excluding any employee benefit
                                   plan (or related trust) maintained or
                                   sponsored by the Company or by the Acquiring
                                   Corporation) beneficially owns, directly or
                                   indirectly, 50% or more of the combined
                                   voting power of the then-outstanding
                                   securities of such corporation entitled to
                                   vote generally in the election of directors
                                   (except to the extent that such ownership
                                   existed prior to the Business Combination).

                  (c)   "Good Reason" shall mean any significant diminution in
                        the Participant's title, authority, or responsibilities
                        from and after the occurrence of a Reorganization Event
                        or Change in Control Event, as the case may be, or any
                        reduction in the annual cash compensation payable to the
                        Participant from and after such Reorganization Event or
                        Change in Control Event, as the case may be, or the
                        relocation of the place of business at which the
                        Participant is principally

<PAGE>

                        located to a location that is greater than 50 miles from
                        its location immediately prior to such Reorganization
                        Event or Change in Control Event.

                  (d)   "Cause" shall mean any (i) willful failure by the
                        Participant, which failure is not cured within 30 days
                        of written notice to the Participant from the Company,
                        to perform his or her material responsibilities to the
                        Company or (ii) willful misconduct by the Participant
                        which affects the business reputation of the Company.

            (2)   Effect on Options

                  (a)   Reorganization Event. Upon the occurrence of a
                        Reorganization Event (regardless of whether such event
                        also constitutes a Change in Control Event), or the
                        execution by the Company of any agreement with respect
                        to a Reorganization Event (regardless of whether such
                        event will result in a Change in Control Event), the
                        Board shall provide that all outstanding Options shall
                        be assumed, or equivalent options shall be substituted,
                        by the acquiring or succeeding corporation (or an
                        affiliate thereof); provided that if such Reorganization
                        Event also constitutes a Change in Control Event, except
                        to the extent specifically provided to the contrary in
                        the instrument evidencing any Option or any other
                        agreement between a Participant and the Company, such
                        assumed or substituted options shall become immediately
                        exercisable in full if, on or prior to the date 18
                        months after the date on which the Reorganization Event
                        is consummated, the Participant's employment with the
                        Company or the acquiring or succeeding corporation is
                        terminated for Good Reason by the Participant or is
                        terminated without Cause by the Company or the acquiring
                        or succeeding corporation. For purposes hereof, an
                        Option shall be considered to be assumed if, following
                        consummation of the Reorganization Event, the Option
                        confers the right to purchase, for each share of Common
                        Stock subject to the Option immediately prior to the
                        consummation of the Reorganization Event, the
                        consideration (whether cash, securities or other
                        property) received as a result of the Reorganization
                        Event by holders of Common Stock for each share of
                        Common Stock held immediately prior to the consummation
                        of the Reorganization Event (and if holders were offered
                        a choice of consideration, the type of consideration
                        chosen by the holders of a majority of the outstanding
                        shares of Common Stock); provided, however, that if the
                        consideration

<PAGE>

                        received as a result of the Reorganization Event is not
                        solely common stock of the acquiring or succeeding
                        corporation (or an affiliate thereof), the Company may,
                        with the consent of the acquiring or succeeding
                        corporation, provide for the consideration to be
                        received upon the exercise of Options to consist solely
                        of common stock of the acquiring or succeeding
                        corporation (or an affiliate thereof) equivalent in fair
                        market value to the per share consideration received by
                        holders of outstanding shares of Common Stock as a
                        result of the Reorganization Event.

                              Notwithstanding the foregoing, if the acquiring or
                        succeeding corporation (or an affiliate thereof) does
                        not agree to assume, or substitute for, such Options,
                        the Board shall, upon written notice to the
                        Participants, provide that all then unexercised Options
                        will become exercisable in full as of a specified time
                        prior to the Reorganization Event and will terminate
                        immediately prior to the consummation of such
                        Reorganization Event, except to the extent exercised by
                        the Participants before the consummation of such
                        Reorganization Event; provided, however, that in the
                        event of a Reorganization Event under the terms of which
                        holders of Common Stock will receive upon consummation
                        thereof a cash payment for each share of Common Stock
                        surrendered pursuant to such Reorganization Event (the
                        "Acquisition Price"), then the Board may instead provide
                        that all outstanding Options shall terminate upon
                        consummation of such Reorganization Event and that each
                        Participant shall receive, in exchange therefor, a cash
                        payment equal to the amount, if any, by which (A) the
                        Acquisition Price multiplied by the number of shares of
                        Common Stock subject to such outstanding Options
                        (whether or not then exercisable), exceeds (B) the
                        aggregate exercise price of such Options. To the extent
                        all or any portion of an Option becomes exercisable
                        solely as a result of the first sentence of this
                        paragraph, upon exercise of such Option the Participant
                        shall receive shares subject to a right of repurchase by
                        the Company or its successor at the Option exercise
                        price. Such repurchase right (1) shall lapse at the same
                        rate as the Option would have become exercisable under
                        its terms and (2) shall not apply to any shares subject
                        to the Option that were exercisable under its terms
                        without regard to the first sentence of this paragraph;
                        provided that if the Reorganization Event is also a
                        Change in Control Event, the shares issued upon exercise
                        of each such Option shall immediately become free from
                        all

<PAGE>

                        conditions or restrictions if, on or prior to the date
                        18 months after the date on which the Change in Control
                        Event is consummated, the Participant's employment with
                        the Company or the acquiring or succeeding corporation
                        is terminated for Good Reason by the Participant or is
                        terminated without Cause by the Company or the acquiring
                        or succeeding corporation.

                  (b)   Change in Control Event that is not a Reorganization
                        Event. Upon the occurrence of a Change in Control Event
                        that does not also constitute a Reorganization Event,
                        except to the extent specifically provided to the
                        contrary in the instrument evidencing any Option or any
                        other agreement between a Participant and the Company,
                        each such Option shall become immediately exercisable in
                        full if, on or prior to the date 18 months after the
                        date on which the Change in Control Event is
                        consummated, the Participant's employment with the
                        Company or the acquiring or succeeding corporation is
                        terminated for Good Reason by the Participant or is
                        terminated without Cause by the Company or the acquiring
                        or succeeding corporation.

            (3)   Effect on Restricted Stock Award

                  (a)   Reorganization Event that is not a Change in Control
                        Event. Upon the occurrence of a Reorganization Event
                        that is not a Change in Control Event, the repurchase
                        and other rights of the Company under each outstanding
                        Restricted Stock Award shall inure to the benefit of the
                        Company's successor and shall apply to the cash,
                        securities or other property which the Common Stock was
                        converted into or exchanged for pursuant to such
                        Reorganization Event in the same manner and to the same
                        extent as they applied to the Common Stock subject to
                        such Restricted Stock Award.

                  (b)   Change in Control Event. Upon the occurrence of a Change
                        in Control Event (regardless of whether such event also
                        constitutes a Reorganization Event), except to the
                        extent specifically provided to the contrary in the
                        instrument evidencing any Restricted Stock Award or any
                        other agreement between a Participant and the Company,
                        each such Restricted Stock Award shall immediately
                        become free from all conditions or restrictions if, on
                        or prior to the date 18 months after the date on which
                        the Change of Control Event is consummated, the
                        Participant's employment with the Company or the
                        acquiring or succeeding corporation is terminated for
                        Good Reason by

<PAGE>

                        the Participant or is terminated without Cause by the
                        Company or the acquiring or succeeding corporation."

2. Section 8(a) of the 2001 Non-Officer, Non-Director Employee Stock Incentive
Plan is deleted in its entirety and the following section is inserted in lieu
thereof:

      "8(a) Transferability of Awards. Except as the Board may otherwise
      determine or provide in an Award, Awards shall not be sold, assigned,
      pledged or otherwise encumbered by the person to whom they are granted,
      either voluntarily or by operation of law, except by will or the laws of
      descent and distribution or, other than in the case of an Incentive Stock
      Option, pursuant to a qualified domestic relations order, and during the
      life of the Participant, shall be exercisable only by the Participant.
      References to a Participant, to the extent relevant in the context, shall
      include references to authorized transferees."

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