Exhibit
10.10  LICENSE AGREEMENT  This
Agreement, effective as of the first day of January, 1995 (the Effective Date)
by and between:  GENZYME CORPORATION, a corporation organized
and existing under the laws of the Commonwealth of Massachusetts and having its
principal office at One Kendall Square, Cambridge, Massachusetts 02139
(hereinafter referred to as GENZYME) and  MOUNT SINAI SCHOOL OF MEDICINE OF THE CITY UNIVERSITY OF NEW YORK, a
not-for-profit corporation organized and existing under the laws of the State
of New York and having its principal office at One Gustave L.  Levy Place, New York, New York 10029
(hereinafter referred to as MSSM).  WITNESSETH  WHEREAS, MSSMhas certain
clinical and preclinical data, information and patent rights relating to the
production and use of recombinant x-galactosidase A for the treatment of Fabry
Disease;  WHEREAS, MSSMdesires to have recombinant
x-galactosidase A developed and made available for general use to patients for
the treatment of Fabry Disease, and for these purposes is willing to grant an
exclusive license to GENZYME upon the terms and conditions set forth below;  WHEREAS, GENZYMEhas or has access to the
research and development capability, the manufacturing capacity and the
marketing ability needed to manufacture and sell recombinant a galactosidase A
therapeutic products in the United States and abroad;  WHEREAS, GENZYMEdesires to obtain an
exclusive, worldwide license under MSSM technology upon the terms and
conditions set forth below;  NOW, THEREFORE, in consideration of the
premises and the mutual covenants contained herein, the parties hereto agree as
follows:  ARTICLE I  - DEFINITIONS  For
the purposes of this Agreement, the following words and phrases shall have the
following meanings:  1.1Affiliate
shall mean any corporation which directly or indirectly controls, is controlled
by or is under common control with GENZYME, control being the ownership of at
least 50% of the outstanding voting stock of such corporation.  1.2First
Commercial Sale shall mean the first arms-length transaction pursuant to this
Agreement to one or more third party of any Product following receipt of
approval to  
 [**] = Portions of
this exhibit have been omitted pursuant to a confidential treatment request. An
unredacted version of this exhibit has been filed separately with the
Commission.  1


commence manufacturing and selling such
Product from the applicable regulatory agency in the applicable country.  1.3Licensed
Patents shall mean the United States and foreign patents and patent
applications set forth in Schedule A attached hereto and owned or controlled by
MSSM, and the United States patents and foreign patents issuing from said
United States and foreign patent applications or later-filed foreign
applications based upon any of said United States patents and application and
any divisions, continuations, continuations-in-part, reissues or extensions of
any of the foregoing.  1.4Product shall
mean an enzyme replacement product for the treatment of Fabry disease, which
includes recombinant x-galactosidase A.  1.5Net Sales
shall mean GENZYMEs gross invoice price for Product less (a) normal cash
and quantity discounts and rebates actually allowed; (b) sales actually
made, but deemed uncollectible; (c) sales and excise taxes and duties
directly imposed, or other governmental charges; (d) outbound
transportation and insurance prepaid or allowed; (e) amounts actually
allowed or credited on account of returns; and (f) other contractual
allowances such as distribution fees.  1.6Technical
Information shall mean any and all proprietary technical data, know-how,
information and material relating to the Product, its manufacture or use, and
set forth in Schedule B attached hereto.  1.7Valid Claim
means a claim of an issued patent within the Licensed Patents that has not
expired or been withdrawn, canceled, disclaimed or held invalid by a court or
governmental agency of competent jurisdiction in an unappealed or unappealable
decision.  ARTICLE II  - GRANT  2.1MSSM hereby
grants to GENZYME an exclusive, worldwide right and license, and subject to
approval by MSSM, which shall not be unreasonably withheld, the right to
sublicense third parties, (a) to make, have made, use, and sell Product
under the Licensed Patents; and (b) to use the Technical Information
provided by MSSM.  MSSM agrees that
[**]other than GENZYME by or under [**] during the term of this Agreement.  2.2GENZYME agrees
to forward to MSSM a copy of any and all sublicense agreements, and further
agrees to forward to MSSM annually a copy of royalty reports related to
royalties received by GENZYME from its sublicensees during the preceding twelve
(12) month period.  2.3GENZYME agrees
to use its reasonable best efforts to substantially manufacture in the United
States that Product which is intended for sale in the United States.  
 [**] = Portions of
this exhibit have been omitted pursuant to a confidential treatment request. An
unredacted version of this exhibit has been filed separately with the
Commission.  2


ARTICLE III  - REPRESENTATIONS AND WARRANTIES  3.1MSSM represents
and warrants that MSSM is the owner of the entire right, title and interest in
and to Licensed Patents, and has the right to grant the license as described
herein, and that the grant of such license will not result in a breach of any
agreement or other undertaking to which MSSM is a party.  3.2MSSM represents
that the United States Government retains rights to the Licensed Patents and
Technical Information.  All rights
granted to GENZYME hereunder are subject to said retained rights as provided in
37 CFR 401 and 45 CFR 8.  ARTICLE IV  - CONSIDERATION  4.1For the rights,
privileges and license granted hereunder, GENZYME shall pay or cause to be paid
to MSSM a royalty of [**] of the Net Sales of Product sold by GENZYME and its
Affiliates and [**] of the royalties payable to GENZYME by any sublicensees for
the longer of (i) the life of the Licensed Patents for Product covered by
Valid Claims in the country of sale, or (ii) [**] years after the First
Commercial Sale of Product.  The royalty
payable to MSSM shall be reduced to [**] of the Net Sales in any country in
which a recombinant x-galactosidase A product derived from mammalian cells is
commercially available from a third party.  4.2No multiple
royalties shall be payable because Product, its manufacture, lease or sale, is
or shall be covered by more than one Valid Claim, patent application or patent
licensed under this Agreement.  4.3Royalty
payments shall be paid to MSSM in United States dollars in New York, N.Y.  Any taxes which GENZYME or any Affiliate or
sublicensee shall be required by law to withhold or pay on remittance of the
royalty payments shall be deducted from royalty paid to MSSM.  GENZYME shall furnish MSSM upon request,
copies of all official receipts for such taxes. 
If any currency conversion shall be required in connection with the
payment of royalties hereunder, such conversion shall be made by using the
exchange rate as reported by the Wall Street Journal on the last business day
of the calendar quarterly reporting period to which such royalty payments
relate or when such conversion rate is next reported.  ARTICLE V  - REPORTS AND RECORDS  5.1GENZYME shall
keep full, true and accurate accounts containing all particulars that may be
necessary for the purpose of showing the amount payable to MSSM.  Said books of account shall be kept at
GENZYME s principal place of business or at such other location that is
reasonably accessible.  Said books and
the supporting data shall be open at all reasonable times, for three (3) years
following the end of the calendar year to which they pertain, to inspection no
more often than once a year by an independent certified public accountant
retained by MSSM, at its expense, solely for the purpose of verifying, under
suitable confidentiality obligations, GENZYMEs royalty statement to MSSM.  If GENZYMEs royalty statement is found to be
in error by [**] or more, such inspection expenses shall be paid by GENZYME.  
 [**] = Portions of
this exhibit have been omitted pursuant to a confidential treatment request. An
unredacted version of this exhibit has been filed separately with the
Commission.  3


5.2Beginning with
the First Commercial Sale, GENZYME, within sixty (60) days after March 31,
June 30, September 30 and December 31, of each year, shall
deliver to MSSM true and accurate reports, giving such particulars of the
business conducted by GENZYME during the preceding quarter under this Agreement
as shall be pertinent to a royalty accounting hereunder.  Reports shall include: (a) total
billings for Product sold; (b) deductions applicable as provided in
Paragraph 1.5; and (c) total royalties due.  5.3With each such
report submitted, GENZYME shall pay to MSSM the royalties then due and
payable.  If no royalties shall be due,
GENZYME shall so report.  ARTICLE VI  - TECHNICAL INFORMATION  6.1Promptly after
the effective date of this Agreement and periodically during the term thereof,
MSSM, to the extent that it has all necessary legal and contractual rights to
do so, shall disclose and furnish to GENZYME all Technical Information which is
requested by GENZYME and which is known or possessed by MSSM.  To enable GENZYME to assist in protecting the
rights licensed to GENZYME hereunder, MSSM shall, provide to GENZYME a [**]
days prior right of review of MSSM publications relating to the Product.  GENZYME may then delay submission up to an
additional [**] days to allow filing of appropriate patent applications.  GENZYME agrees to review oral disclosures or
abstracts within [**] days of notification, and MSSM agrees to delete
proprietary information as requested by GENZYME.  6.2Each of the
parties, for itself and its Affiliates, undertakes during the term of this
Agreement, to hold in confidence and not to disclose to any third party, the
Technical Information received from the other, provided that such undertaking
shall not apply to any portion of said Technical Information which:  (a)was known to
the receiving party or any of its Affiliates prior to its receipt by the
receiving party or any of its Affiliates hereunder;  (b)is received at
any time by the receiving party or any of its Affiliates in good faith from a
third party lawfully in possession of the same and having the right to disclose
the same;  (c)is as of the
date of the receipt by the receiving party or any of its Affiliates in the
public domain or subsequently enters the public domain other than by reason of
acts or omissions of the employees or agents of the receiving party or any of
its Affiliates;  and
provided further that nothing contained herein shall prevent GENZYME or any of
its Affiliates from using and disclosing the Technical Information received
from MSSM in connection with applying for and securing governmental
authorizations for the marketing of licensed products or otherwise in the
performance of its obligations under this Agreement.  
 [**] = Portions of
this exhibit have been omitted pursuant to a confidential treatment request. An
unredacted version of this exhibit has been filed separately with the
Commission.  4


ARTICLE VII  - PATENT SUPPORT AND PROSECUTION  7.1GENZYME shall
[**] on a quarterly basis for [**] after the date of this Agreement in
connection with the filing, prosecution and maintenance of all Licensed Patents
filed, prosecuted or maintained at the request of GENZYME.  GENZYME shall not be required to [**].  If GENZYME elects not to [**], MSSM shall be
free to license such patent to any other party.  7.2MSSM shall seek
prompt issuance of, and maintain, [**], the Licensed Patents, and shall keep
GENZYME informed of, and shall provide to GENZYME copies of, all official
documents received from and sent to governmental patent offices.  MSSM shall keep GENZYME apprised on a timely
basis of the progress of any patent prosecution, and shall provide GENZYME with
a reasonable opportunity to preview and comment upon prosecution
responses.  MSSM agrees to reasonably
consider any such comments provided by GENZYME.  7.3If MSSM shall
decide to discontinue any such prosecution, or shall decide not to maintain any
patent, or not to file a patent application on an invention relating to the
Product, or not to file same in a particular country, it shall promptly notify
GENZYME in writing and in reasonably sufficient time for GENZYME to assume such
prosecution or maintenance, or file such patent application, and shall take the
necessary steps and execute the necessary documents to permit GENZYME to assume
the filing, prosecution, or maintenance of the same at GENZYMEs expense and
control, whereupon GENZYME shall possess a royalty-free, exclusive license to
same for the life of any such patent.  ARTICLE VIII  - INFRINGEMENT  8.1MSSM shall have
the first option to institute and prosecute [**] suits for infringement of
Licensed Patents.  Any recovery of
damages shall [**].  8.2If MSSM elects
not to bring an action for infringement, GENZYME shall have the power, but not
the obligation, to institute and prosecute [**] suits for infringement of
Licensed Patents.  MSSM agrees to join as
party plaintiff in any such suits instituted by GENZYME, and shall fully
cooperate with GENZYME in the prosecution of such suits.  GENZYME may withhold up to [**] of royalties
due hereunder during the pendency of such suits and GENZYME may apply such
withheld amounts toward reimbursement of its expenses, including reasonable
attorneys fees in connection therewith. 
Any recovery of damages by GENZYME shall be applied first in
satisfaction of any unreimbursed expenses and legal fees relating to the suit
or settlement thereof, and then toward reimbursement of MSSM for any royalties
withheld and applied pursuant to this Article VIII.  Any remaining recoveries shall be deemed Net
Sales for purposes of calculation of royalties hereunder.  8.3If GENZYME does
not bring action, and MSSM chooses not to bring action, to halt infringement,
then the applicable royalty in such country shall be [**] of the rate otherwise
applicable, provided that GENZYME has suffered at least a [**] market share
loss due to such infringement.  
 [**] = Portions of
this exhibit have been omitted pursuant to a confidential treatment request. An
unredacted version of this exhibit has been filed separately with the
Commission.  5


ARTICLE IX  - TERM AND TERMINATION  9.1This Agreement
shall be effective as of the date first written above and shall continue in
effect on a country-by-country basis until the later of (i) the expiration
of the last to expire of the Licensed Patents in a particular country, or (ii) ten
(10) years after the date of the First Commercial Sale.  Thereafter, Genzyme shall have a paid up
license to the Technical Information.  9.2Should GENZYME
fail in its payment to MSSM of royalties due in accordance with the terms of
this Agreement, MSSM shall have the right to serve notice upon GENZYME by
certified mail at the address designated in Article XVI hereof, of its
intention to terminate this Agreement within [**] days after receipt of said
notice of termination unless GENZYME shall pay to MSSM within the [**] day
period, all such royalties due and payable, or institute arbitration
proceedings as provided herein.  Upon the
expiration of the [**] day period, if GENZYME shall not have paid all such
royalties due and payable, or implemented arbitration, the rights, privileges
and license granted hereunder shall thereupon immediately terminate.  9.3Upon any
material breach or default of this Agreement by either party, other than those
occurrences set out in Paragraph 9.2 above, the other party shall have the
right to terminate this Agreement and the rights, privileges and license
granted hereunder by [**] days notice including a detailed explanation of the
reasons for termination, by certified mail to the defaulting party.  Such termination shall become effective
unless the defaulting party shall have cured any such breach or default prior
to the expiration of the other partys notice of termination.  9.4GENZYME shall
have the right, upon [**] days written notice, to terminate the license granted
herein, on a country-by-country basis or to fully terminate the license and
this Agreement.  9.5Upon
termination of this Agreement for any reason, nothing herein shall be construed
to release either party from any obligation that matured prior to the effective
date of such termination.  GENZYME and its
Affiliates and sublicensees may, however, after the effective date of such
termination, sell all Product, and complete Product in the process of
manufacture at the time of such termination and sell the same, provided that
GENZYME shall pay to MSSM the royalties thereon as required by Article IV
of this Agreement and shall submit the reports required by Article V
hereof on the sales of Product.  9.6The provisions
of Article VI shall survive termination of this Agreement for a period of
five (5) years.  The provisions of Article XII
shall survive termination of this Agreement.  ARTICLE X  - ARBITRATION  Except
as to issues relating to the validity, construction or effect of any patent
licensed hereunder, any and all claims, disputes or controversies arising
under, out of, or in connection with this Agreement, which have not been
resolved by good faith negotiations between the parties, shall be resolved by
final and binding arbitration in Boston, Massachusetts by three  
 [**] = Portions of
this exhibit have been omitted pursuant to a confidential treatment request. An
unredacted version of this exhibit has been filed separately with the
Commission.  6


arbitrators, one selected by each party
within 30 days of receipt of notice to arbitrate, the remaining arbitrator to
be selected by the party- selected arbitrators. 
If a party fails to select an arbitrator within the thirty day period,
it shall forfeit its right to make such a selection.  The arbitration shall be under the rules of
the American Arbitration Association then obtaining.  The arbitrators shall have no power to modify
any of the terms or conditions of this Agreement.  Any award rendered in such arbitration may be
enforced by any of the parties in the United States District Court for
Massachusetts, to whose jurisdiction for such purposes MSSM and GENZYME each
hereby irrevocably consents and submits. 
Each party shall bear its own costs.  ARTICLE XI  - THIRD PARTY PATENTS  In
the event that a patent of a third party should exist during the term of this
Agreement, which such third party alleges is infringed by the manufacture, use
or sale of Product by GENZYME, or in the event that GENZYME shall undertake to
challenge the validity or infringement of such patent by litigation, GENZYME
may withhold up to [**] of the royalties otherwise due to MSSM towards the
reimbursement of its out-of-pocket costs and expenses incurred in such
litigation, and/or if GENZYME is required to pay to such other patentee a royalty
under such patent, GENZYME may deduct up to [**] of the royalties paid to such
third party.  In no event, however, shall
the deductions allowed in this Article XI cause the total royalty payable
to MSSM under Article 4.1 of this Agreement to be less than [**] of Net
Sales.  ARTICLE XII  - INSURANCE AND INDEMNIFICATION  12.1GENZYME shall
at all times during the term of this Agreement and thereafter, defend,
indemnify and hold MSSM, its affiliates and their trustees, directors,
officers, employees, medical staff, agents, volunteers and students harmless
from any and all claims, demands, lawsuits, actions, settlements, judgments,
and expenses (including legal expenses and attorneys fees), arising from or in
connection with the negligent acts or omissions or product liabilities of
GENZYME, its Affiliates, employees or other agents committed in connection with
this Agreement.  MSSM shall be required
to provide GENZYME with prompt notice of any such claims, as well as such
reasonable assistance and cooperation as GENZYME may request in the defense of
such claims.  GENZYMES obligation to
protect, defend, indemnify and hold harmless hereunder shall Survive the
expiration and termination of this Agreement.  12.2GENZYME shall
purchase and keep in force the following minimum insurance coverages, naming
MSSM as additional insured with such insurers as shall be acceptable to MSSM:  1)
Comprehensive General Liability, including:  (a)Personal injury
and bodily injury and Broad form property damage liability with a combined
single limit of not less than $[**].  (b)Coverage for
the contractual liability assumed by this Agreement.  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.  7


2)
Product liability insurance in an amount not less than [**] per occurrence,
with an aggregate yearly limit of [**]. 
Prior to any work being performed under this Agreement, GENZYME shall
deliver to MSSM certificates of insurance evidencing that the coverages
specified in these sections are in effect. 
Such certificates shall show that:  (a)MSSM is an
additional named insured;  (b)the insurer
shall give MSSM thirty (30) days written notice sent by registered mail of any
material change in, or cancellation of, such insurance.  ARTICLE XIII  - ASSIGNMENT  13.1GENZYME shall
be entitled to assign its rights hereunder, with the written consent of MSSM,
which consent shall not be unreasonably withheld.  At GENZYMEs request, MSSM shall enter into a
separate counterpart agreement with any such assignee, it being expressly
agreed that GENZYME shall remain bound by the obligations hereof until such
separate counterpart agreement is signed. 
Such counterpart agreement shall be the same in form and substance
except for necessary changes to reflect the extent of the assignment.  13.2MSSM shall be
entitled to assign its rights hereunder with the written consent of GENZYME, which
consent shall not be unreasonably withheld.  ARTICLE XIV  - NON-USE OF NAMES AND TRADEMARKS  14.1Neither party
shall use the names or trademarks of the other party for any advertising,
promotional or sales literature without prior written consent which consent
shall not be unreasonably withheld, except that GENZYME may disclose that it is
exclusively licensed by MSSM hereunder. 
In all cases, GENZYME shall be permitted to make such disclosures as
required by state and federal law.  14.2It is understood
that MSSM has selected the trademark [**] for use in connection with the
Product.  GENZYME agrees to reasonably
consider said trademark for use in connection with its commercialization of the
Product, and MSSM agrees to assign its rights to said trademark to GENZYME at
no cost, upon GENZYMEs request.  ARTICLE XV  - DUE DILIGENCE  GENZYME
shall use its reasonable efforts to develop the Product for
commercialization.  Such efforts shall
include the following:  (a)within [**]
years of the Effective Date, to initiate [**] studies on the Product which is
intended for use in clinical trials;  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.  8


(b)within [**]
years of the Effective Date to initiate [**] for the Product; and  (c)within [**]
years of the Effective Date to [**].  ARTICLE XVI  - PAYMENTS, NOTICES AND OTHER COMMUNICATIONS  Any
payment, notice or other communication pursuant to this Agreement shall be
sufficiently made or given on the date of mailing if sent to such party by
certified first class mail, postage prepaid, addressed to it as its address
below or as it shall designate by written notice given to the other party:  In
the case of MSSM: Office
of Science and Technology Development Mount Sinai School of Medicine One
Gustave L.  Levy Place New
York, NY 10029 Attention:
Dr.  Frank Landsberger Fax.  No.  (212) 348-3116  In
the case of GENZYME: Genzyme
Corporation One Kendall Square Cambridge,
MA 02139 Attention:
Senior Vice President and General Counsel Fax.  No.  (508) 872-5415  ARTICLE XVII  - MISCELLANEOUS PROVISIONS  17.1This Agreement
shall be construed, governed, interpreted and applied in accordance with the
laws of the State of New York, except that questions affecting the construction
and effect of any patent shall be determined by the law of the country in which
the patent was granted.  17.2The parties hereto
acknowledge that this Agreement and the Research Agreement dated of even date
sets forth the entire agreement and understanding of the parties hereto as to
the subject matter hereof, and shall not be subject to any change or
modification except by the execution of a written instrument subscribed to by
the parties hereto.  17.3The provisions
of this Agreement are severable, and in the event that any provision of this
Agreement shall be determined to be invalid or unenforceable under any
controlling body of law, such invalidity or unenforceability shall not in any
way effect the validity or enforceability of the remaining provisions hereof.  17.4The failure of
either party to assert a right hereunder or to insist upon compliance with any
term or condition of this Agreement shall not constitute a waiver of that right
or excuse a similar subsequent failure to perform any such term or condition by
the other party.  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.  9


17.5Neither party
shall, without the consent of the other, which consent shall not be
unreasonably withheld, originate any publicity, news release, or other public
announcement, written or oral, whether to the public press, to stockholders, or
otherwise, relating to this Agreement, any amendment hereto or performance
hereunder, save any such announcement as in the opinion of legal counsel to the
party making such announcement is required by law to be made.  Both parties acknowledge the likelihood that
GENZYME may be required to make a general announcement regarding the existence of
this Agreement as a material event.  The
party making such announcement will give the other party an opportunity to
review the form of the announcement before it is made.  17.6Both parties
acknowledge and recognize the presence of risk regarding the development and
sale of the Product contemplated hereunder, that potential markets discussed
have only been estimated and are not being relied upon, and that the Product
may be unsuccessful in any such market.  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.  10


IN WITNESS WHEREOF, the parties
hereto have caused this License Agreement to be executed by their duly authorized
representatives as of the day and year first set forth above.  MOUNT
  SINAI SCHOOL OF MEDICINE
  
  GENZYME
  CORPORATIONBY:
  /s/[illegible] Katz
  
  BY:
  /s/
  Gregory D. PhelpsTITLE:
  [illegible]
  
  TITLE:
  Senior
  Vice PresidentDATE:
  1-27-95
  
  DATE:
  2-3-95ACCEPTED
  AND AGREED TO:NAME:
  /s/
  Robert J. DesnickRobert J. Desnick, Ph.D., M.D.DATE:
  1-26-95  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.  11


SCHEDULE A  A.  United States Patents and Application6923-005
  
  U.S. Patent No.  5,356,804Granted:  October 18, 1994To:
  Desnick et al.For:
  Cloning And Expression Of
  Biologically ActiveAlpha Galactosidase ABy:
  Desnick
  et el.6923-030
  
  U.S. Serial No. 
  07/903,451 (allowed)Filed:  November 30, 1992For:
  Cloning And Expression Of Biologically
  Active Alpha-Galactomidase ABy:
  Desnick et al.6923-042
  
  U.S. Serial No. 
  00/261,577 (pending)Filed: June 17, 1994 (as a
  division of Serial No. 07/983,451)For:
  Cloning And Expression Of
  Biologically Active Alpha-Galactosidase ABy:
  Desnick et al.B.Foreign Patents and Applications6923-030-228
  
  International Application
  No.  PCT/US93/11539Filed: November 30, 1993For:
  Cloning And Expression Of
  Biologically Active Alpha-Galactosidase ABy:
  Desnick et al.6923-030-158
  
  Israeli Application No. 
  107814Filed: November 30, 1993For:
  Cloning And Expression Of
  Biologically Active Alpha-Galactooidaso ABy
  Desnick et al.  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.


Schedule B Technical Information  [**]  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.


FIRST AMENDMENT TO LICENSE AGREEMENT  This
is the First Amendment to the January 1, 1995 License Agreement between
Genzyme Corporation (GENZYME) and Mount Sinai School of Medicine of the City
University of New York (MSSM).  This
Amendment shall be effective as of October 7, 2003.  WHEREAS,
in the License Agreement, MSSM has granted to GENZYME an exclusive license
under certain Technical Information and Licensed Patents rights, including
U.S.  patent No.  5,356,804 (the 804
patent), in connection with the commercialization of recombinant"-galactosidase
A for the treatment of Fabry Disease; and  WHEREAS,
MSSM and Genzyme are co-plaintiffs and appellants in a suit against
Transkaryotic Therapies, Inc.  (TKT)
alleging infringement of the 804 patent (the Infringement Suit), which
Infringement Suit was originally brought in the United States District Court
for the District of Delaware (Civil Action No.  00-677 GMS) and is now on
appeal to the Court of Appeals for Federal Circuit (Appeal No.  02-1312);  NOW,
THEREFORE, in consideration of the premises and the mutual covenants contained
herein and for other good and valuable consideration, the receipt and sufficiency
of which each party acknowledges, MSSM and GENZYME hereby agree as follows:  1.Definitions.  Capitalized terms not defined in this First
Amendment shall have the meaning given them in the License Agreement.  2.Restatement
of Section 2.1.Section 2.1 of the License Agreement
shall be amended and restated to read as follows:  2.1Except as provided in Article XVIII,
MSMM hereby grants to GENZYME an exclusive, worldwide right and license, and
subject to approval by MSMM, which shall not be unreasonably withheld, the
right to sublicense third parties, (a) to make, have made, use, and sell
Product under the Licensed Patents; and (b) to use the Technical
Information provided by MSSM.  MSSM
agrees that [**] other than GENZYME [**] by or under [**] during the term of
this Agreement.  3.Addition
of Article XVIII.  New Article XVIII
shall be added to the License Agreement, which Article shall read as
follows:  ARTICLE XVIII
 INFRINGEMENT SUIT AGAINST TKT  18.1.1In the event
that GENZYME withdraws as plaintiff-appellant from the Infringement Suit, MSSM
shall have the right (i) to continue the proceedings and maintain the
Infringement Suit as the sole plaintiff [**] and (ii) to solely bring,
defend or maintain any other proceeding relating to the Licensed Patents or
Technical Information in which TKT is a party or has an interest [**].  Notwithstanding the foregoing, GENZYME shall
[**] from any [**] for which [**] to the extent arising out of or related to (i) [**]
or (ii) any agreement between  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.


[**].  In addition, only to the extent permitted by
any Settlement Agreement, GENZYME [**] shall reasonably cooperate with MSSMs
prosecution of the Infringement Suit or any other action related to the
Licensed Patents or Technical Information. 
Such cooperation includes making available to MSSM any documents,
witnesses, or other information in GENZYMEs control.  18.2Any [**] in the Infringement
Suit or any other proceeding between [**].  18.3Notwithstanding the
provisions of Section 2.1, MSSM shall have [**].  4.Acknowledgements.GENZYME and MSSM acknowledge that, if GENZYME
withdraws from the Infringement Suit:  a.Effective as of
the date GENZYME withdraws, GENZYME confirms that, [**].  For the avoidance of doubt, amounts
previously [**].  b.Section 8.3
of the License Agreement shall not apply to [**], or their respective successors,
assigns or licensees.  Except
as provided herein, the License Agreement shall remain in full force and
effect.  Any capitalized terms used
herein but not otherwise defined shall have the meanings ascribed to them in
the License Agreement.  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.


IN
WITNESS WHEREOF, the Parties hereto have caused this Amendment to
be executed and delivered as of the effective day and year set forth above.   MOUNT SINAI SCHOOL OF MEDICINE
  
  GENZYME
  CORPORATIONBy:
  /s/
  Kenneth L. Davis
  
  By:
  /s/
  Thomas DesRosierKenneth L. Davis, M.D.Title:
  Dean
  
  Title:
  Senior
  Vice PresidentDate:
  10-7-2003
  
  Date:
  10-7-2003  
 [**] = Portions of this exhibit have been
omitted pursuant to a confidential treatment request. An unredacted version of
this exhibit has been filed separately with the Commission.