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                                                                   Exhibit 10.17

              AMENDMENT NO. 1 TO AMENDED AND RESTATED COLLABORATION
              AGREEMENT BETWEEN GENZYME CORPORATION AND DYAX CORP.

     This Amendment No. 1 (the "Amendment") to the Amended and Restated
Collaboration Agreement dated May 31, 2002 (the "Agreement") by and between
Genzyme Corporation, with its principal office at One Kendall Square, Cambridge,
Massachusetts 02139 ("Genzyme"), and Dyax Corp., with a principal office at 300
Technology Square, Cambridge, Massachusetts 02139 ("Dyax") is effective as of
September 30, 2003 ("Amendment Effective Date"). Terms not otherwise defined
herein shall have the respective meanings attributed to them in the Agreement.

     WHEREAS, Genzyme and Dyax are parties to the Agreement, pursuant to which
the parties agreed to collaborate in developing DX-88 for the treatment of
hereditary angioedema and other inflammatory diseases; and

     WHEREAS, Genzyme and Dyax now wish to modify the terms of their
collaboration and amend certain provisions of the Agreement;

     NOW, THEREFORE, in consideration of the promises and agreements set forth
herein, and for other good and valuable consideration, Genzyme and Dyax hereby
agree as follows:

1.   The parties acknowledge and agree that on June 26, 2003, Genzyme elected to
exercise its Buy-In Option. As a result, all rights and obligations of Genzyme
contained in the Agreement that are contingent upon Genzyme's exercise of its
Buy-In Option shall hereafter be deemed to be current and fully enforceable
rights and obligations.

2.   Section 1.15 of the Agreement ("Field") shall be amended and restated as
follows:

     "FIELD" shall mean any and all therapeutic uses of a Collaboration Product,
     excluding uses relating to the Surgical Product.

3.   Section 1.31 of the Agreement ("Percentage Interest") shall be amended and
restated as follows:

     "PERCENTAGE INTEREST" shall have the meaning set forth in the Operating
     Agreement. If Genzyme exercises its Buy-In Option pursuant to Section 4.2
     hereof, the Percentage Interests of the Parties shall be adjusted such that
     the Percentage Interest of Dyax shall be fifty and one one hundredth
     percent (50.01%) and the Percentage Interest of Genzyme shall be forty-nine
     and ninety-nine hundredths percent (49.99%).

4.   In Section 2.1 of the Agreement ("General"), the term "fifty percent (50%)"
in the seventh sentence of Section 2.1 shall be deleted, and the term
"forty-nine and ninety-nine hundredths percent (49.99%)" shall be inserted in
its place.

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5.   In Section 3.2 of the Agreement ("Proposals for Additional Indications"),
the last two sentences of Section 3.2 shall be deleted in their entirety and
replaced with the following:

     Genzyme hereby acknowledges and agrees that it shall have no rights with
     respect to the Surgical Product including, without limitation, the right to
     receive royalties in connection therewith.

6.   In Section 4.2 of the Agreement ("Buy-In Option"), the term "fifty percent
(50%)" in the first sentence of Section 4.2 shall be deleted, and the term
"forty-nine and ninety-nine hundredths percent (49.99%)" shall be inserted in
its place.

7.   Section 4.3.1 of the Agreement ("General"), shall be amended and restated
as follows:

     If Genzyme elects to exercise its Buy-In Option, Genzyme shall pay Dyax an
     amount equal to fifty percent (50%) of all Program Costs incurred or
     accrued after satisfaction of the Initial Funding Commitment through the
     LLC Formation Date. The Percentage Interests of Dyax and Genzyme in
     Kallikrein LLC are set forth in Section 5.1(b) of the Operating Agreement.
     In the event that either Dyax or Genzyme fails to make a capital
     contribution to Kallikrein LLC as required by this Section 4.3 and Section
     5.1(b) of the Operating Agreement, and the other Party does not elect to
     terminate this Agreement pursuant to Section 13.2.1 hereof, then the
     Percentage Interests in Kallikrein LLC and the future funding
     responsibility of the Members shall be adjusted as provided in Section
     5.1(b) of the Operating Agreement.

8.   Section 4.3.2 of the Agreement ("Initial Capital Contributions") shall be
amended and restated as follows:

     If Genzyme elects to exercise its Buy-In Option, within five (5) working
     days after the execution and delivery of the Purchase Agreement, Dyax shall
     make a capital contribution to Kallikrein LLC in an amount equal to fifty
     and one one hundredth percent (50.01%) and Genzyme shall make a capital
     contribution to Kallikrein LLC in an amount equal to forty-nine and
     ninety-nine hundredths percent (49.99%) of the Program Costs incurred by
     Kallikrein LLC from the LLC Formation Date through and including September
     30, 2003.

9.   In Section 4.5 of the Agreement ("Sale and Purchase of LLC Interest"), the
term "fifty percent (50%)" shall be deleted, and the term "forty-nine and
ninety-nine hundredths percent (49.99%)" shall be inserted in its place.

10.  In Section 13.3.2(d) of the Agreement, in the fifth line of that
sub-section, the phrase "in the event that Dyax is the non-terminating Party"
shall be deleted, and the phrase "in the event that Dyax is the terminating
Party" shall be inserted in its place.

11.  Subsidiary is no longer a Member of Kallikrein LLC, consequently, all
references to Subsidiary in the Agreement shall be deleted. All references to
"Dyax Companies" in the Agreement shall be deemed to refer only to Dyax.

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12.  Except as expressly modified hereby, the terms of the Agreement remain
unchanged and in full force and effect and shall govern and apply to all matters
contemplated by this Amendment.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed by their respective duly authorized representatives as of the Amendment
Effective Date.


GENZYME CORPORATION                     DYAX CORP.


By:    /s/ G. Jan van Heek              By:    /s/ Henry E. Blair
       ------------------------------          --------------------------------
Name:  G. Jan van Heek                  Name:  Henry E. Blair
Title: Executive Vice President         Title: Chairman, President and Chief
                                               Executive Officer
Date:  9/30/03                          Date:  9/30/03