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                                                         EXHIBIT 99

             IMPORTANT FACTORS REGARDING FORWARD-LOOKING STATEMENTS

    March 1997

    From time to time, GTC, through its management, may make forward-looking
public statements, such as statements concerning then expected future revenues
or earnings or concerning projected plans, performance, product development and
commercialization as well as other estimates relating to future operations.
Forward-looking statements may be in reports filed under the Securities Exchange
Act of 1934, as amended, in press releases or in oral statements made with the
approval of an authorized executive officer. The words or phrases "will likely
result," "are expected to," "will continue," "is anticipated," "estimate,"
"project," or similar expressions are intended to identify "forward-looking
statements" within the meaning of Section 21E of the Securities Exchange Act of
1934 and Section 27A of the Securities Act of 1933, as enacted by the Private
Securities Litigation Reform Act of 1995.

    The Company wishes to caution readers not to place undue reliance on these
forward-looking statements which speak only as of the date on which they are
made. In addition, the Company wishes to advise readers that the factors listed
below, as well as other factors not currently identified by management, could
affect the Company's financial or other performance and could cause the
Company's actual results for future periods to differ materially from any
opinions on statements expressed with respect to future periods or events in any
current statement.

    The Company will not undertake and specifically declines any obligation to
publicly release any revisions which may be made to any forward-looking
statements to reflect events or circumstances after the date of such statements
or to reflect the occurrence of anticipated or unanticipated events which may
cause management to re-evaluate such forward-looking statements.

    In connection with the "safe harbor" provisions of the Private Securities
Litigation Reform Act of 1995, the Company is hereby filing cautionary
statements identifying important factors that could cause the Company's actual
results to differ materially form those projected in forward-looking statements
of the Company made by or on behalf of the Company.

    History of Operating Losses; Need for Additional Funds. GTC has had
operating losses since its inception and expects such losses to continue for the
next several years. For the period from its inception in 1993 to December 29,
1996, the Company incurred cumulative losses of approximately $17.9 million.
GTC's losses have resulted principally from costs incurred in connection with
research activities and from expenses in excess of revenues from the Company's
CRO services. GTC's sources of revenues to date have consisted primarily of
research and development contracts and CRO services. Such revenues to date have
not been sufficient to generate profits. The Company expects to continue to
incur significant operating losses until such time as product sales and CRO
service revenues are sufficient to fund its operations. No assurance can be
given that the Company will become profitable.
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  The Company currently believes that existing cash resources and available
financing will be sufficient to meet its operating cash flow needs and capital
requirements at least through the end of 1997. The development of transgenic
products by the Company will require the commitment of substantial resources to
conduct costly and time-consuming research, preclinical testing and clinical
trials necessary to bring such products to market. If GTC's businesses do not
achieve profitable operations at or prior to the time such existing resources
are exhausted, the Company will need to obtain additional financing, through
public or private financings, including debt or equity financings, or through
collaborative or other arrangements with corporate partners, as appropriate.
Adequate funds for the Company's operations from such sources may not be
available when needed or on terms acceptable to the Company. If additional
financing cannot be obtained when needed or on acceptable terms, GTC could be
forced to delay, scale back or eliminate certain of its research and development
programs or to license to other parties rights to commercialize
 products or technologies that the Company would otherwise seek to develop
internally as well as delaying or forgoing timely expansion, improvement or
investment in the Company's contract research services.

    The foregoing forward-looking statements regarding the Company's
expectations of the need for additional funds are subject to risks and
uncertainties. The Company's cash requirements may vary materially from those
now planned, depending upon the results of existing businesses, the terms of
future collaborations, results of research and development, competitive and
technological advances, regulatory requirements and other factors.

    Early Stage of Transgenic Technology.  Development of products based on
transgenic technology is subject to a number of significant technological risks
and the time period required for any such development is both lengthy and
uncertain. Neither GTC nor, to GTC's knowledge, any other entity has conducted
human clinical trials of any protein produced in the milk of transgenic animals
and there can be no assurance that GTC will be able to do so successfully. There
can be no assurance that any transgenically produced protein will be safe or
effective. All of the proteins that GTC is developing will require significant
additional research, development and testing and will require the expenditure of
substantial additional capital prior to their commercialization. In addition,
there can be no assurance that research and discoveries by others will not
render GTC's technology obsolete or noncompetitive.

    No Assurance of Commercial Success of Transgenic Products . The successful
commercialization of any transgenic protein product by the Company will depend
on many factors, including the successful completion of clinical testing, the
response of medical professionals to the data from clinical trials, the
Company's ability to create or access a sales force able to market such
transgenic products, the Company's ability to supply a sufficient amount of
product to meet market demand, the degree to which third-party reimbursement for
use of such product is available and the number and relative efficacy of
competitive products that may subsequently enter the market, as well as, with
respect to transgenic products designed to replace or supplement products
currently being marketed, the relative cost-effectiveness of the transgenic
products. There can be no assurance that the Company or its collaborative
partners will be successful in efforts to develop and implement a
commercialization strategy for any such products.
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    GTC does not currently have a sales force to market any transgenic products
it may develop. The Company anticipates that, for products it develops
independently, it will enter into marketing arrangements with larger
pharmaceutical or biotechnology companies which have established sales forces
that are able to market such products. There can be no assurance that any
marketing or distribution arrangements will be available on acceptable terms or
that, in the alternative, GTC will be able to establish its own sales force
successfully. Unforeseen delays in this process may have an adverse effect on
the commercialization of any of the Company's products.

    Third-party payors are increasingly attempting to contain health care costs
by limiting both coverage and the level of reimbursement for new therapeutic
products. The successful commercialization of any products developed by the
Company may depend on obtaining coverage and reimbursement for the use of these
products from third-party payors.

    In addition, the successful commercialization of the Company's products will
require that medical professionals become convinced of the efficacy of the
products in treating a particular condition and incorporate such products as
standard practice in relevant therapeutic protocols. There can be no assurance
that any transgenic product developed by GTC will be accepted by the medical
profession.

    Retention of Key Personnel.  Although GTC believes that the size and
qualifications of its current staff are adequate for its current business, the
Company must continue to attract and retain qualified scientific, technical,
marketing and management personnel as its business expands. There is intense
competition for qualified personnel in the areas of the Company's activities,
and there can be no assurance that GTC will be able to continue to attract and
retain the qualified personnel necessary for the development of its
business. Loss of the services of, or failure to recruit, key scientific and
technical personnel could have a material adverse effect on GTC's business.

    Government Regulation.  Transgenic products will require approval by the FDA
prior to marketing in the United States. In addition, the manufacturing and
marketing of such products, and certain areas of research related to them, are
subject to regulations by other U.S. governmental authorities including the
United States Department of Agriculture (the "USDA") and the Environmental
Protection Agency (the "EPA"). Comparable authorities are involved in other
countries.

    In cases where the Company expects to obtain revenue from the sale of
transgenic products, whether through direct sales, marketing relationships with
others or royalty arrangements, the Company will incur the risk of such product
failing to satisfy applicable regulatory requirements prior to marketing. The
approval process involves two parts, governing first the approval of an
individual pharmaceutical product as safe and effective and second the approval
of the manufacturing process as complying with applicable FDA current good
manufacturing practices regulations ("GMPs"). In 1995, the FDA and comparable
European regulatory authorities issued guidelines regarding the production of
therapeutic proteins in transgenic animals. While the FDA's guidelines, known as
Points to Consider guidelines ("Points to Consider"), cover issues specific to
transgenic production, the basic regulatory framework for FDA approval will also
apply to transgenic therapeutic products submitted for approval. To GTC's
knowledge, no protein produced in the milk of a transgenic animal has been
submitted for regulatory approval in the United States or elsewhere.
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    The FDA and comparable agencies in foreign countries impose substantial
requirements upon the introduction of therapeutic pharmaceutical products
through lengthy and detailed laboratory and clinical testing procedures,
sampling activities and other costly and time-consuming procedures. Satisfaction
of these requirements typically takes several years or more and can vary
substantially based upon the type, complexity and novelty of the product. With
respect to therapeutic products, the standard FDA approval process includes
preclinical laboratory and animal testing, submission of an IND to the FDA,
appropriate human clinical trials to establish safety and effectiveness and
submission of either a Biologics License Application or a New Drug Application
("NDA") prior to market introduction. With respect to obtaining approval for the
production facilities to be used in producing a therapeutic product, the Company
expects to be subject to both the requirements for establishment license
applications and the Points to Consider issued with respect to transgenic
recombinant products.

    The effect of government regulation may be to delay marketing of the
Company's products for a considerable or indefinite period of time, impose
costly procedural requirements upon the Company's activities and may furnish a
competitive advantage to larger companies or companies more experienced in
regulatory affairs. There can be no assurance that FDA or other regulatory
approvals for any products developed by the Company will be granted on a timely
basis or at all. Any delay in obtaining or any failure to obtain such approvals
could adversely affect the Company's ability to generate revenue. Even if
initial regulatory approvals for the Company's product candidates are obtained,
the Company, its products and its transgenic manufacturing processes would be
subject to continual review and periodic inspection. There can be no assurance
that the FDA will permit the marketing of any transgenic product for any
particular indication, if at all.

    The Company's operations are also subject to federal, state and local laws,
rules, regulations and policies governing the use, generation, manufacture,
storage, air emission, effluent discharge, handling and disposal of certain
materials and waste, including but not limited to animal waste and waste water.

    Dependence of Testing Services on Current Government Regulatory
Requirements. The market for GTC's preclinical testing services is dependent
upon the maintenance of strict standards for the conduct of laboratory and
clinical tests and related procedures which are promulgated by governmental
entities responsible for public health and welfare, including the FDA, and by
regulatory authorities in foreign countries. The process of obtaining these
approvals varies according to the nature and use of the product
 and routinely involves lengthy and detailed laboratory and clinical testing and
other costly and time-consuming procedures. The Company offers the customers of
its preclinical testing and development services the necessary expertise to
comply with these complex regulations. If the regulatory structure were to
change in a way which reduced the need for such services, the Company could be
materially adversely affected.
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    Uncertainty Regarding Patents and Proprietary Technology . GTC has relied
upon trade secrets, proprietary know-how and continuing technological innovation
to develop and maintain its competitive position and to protect its proprietary
technology. In part, these legal rights are protected by contracts with
employees, consultants and business partners. There can be no assurance that
trade secrets possessed by GTC will be maintained, that secrecy obligations will
be honored or that others will not independently develop similar or superior
technology. There is no assurance that patent applications filed by GTC will
result in patents being issued or that any patents issued to or licensed by GTC
will be held valid. The Company may also be subject to claims that result in the
revocation of patent rights previously licensed to GTC as a result of which the
Company may be required to obtain licenses from others to continue to develop,
test or commercialize its products. There can be no assurance that GTC will be
able to obtain such licenses on acceptable terms, if at all. In addition, there
may be pending or issued patents held by parties not affiliated with GTC that
relate to the technology utilized by GTC. As a result, GTC may need to acquire
licenses to, or contest the validity of, such patents or any other similar
patents which may be issued. GTC could incur substantial costs in defending
itself against challenges to patent or infringement claims made by third parties
or in enforcing any patent rights of its own. The loss or exposure of trade
secrets possessed by GTC could also adversely affect its business.

    On December 21, 1995, Pharming B.V. filed a request for arbitration under a
cross-license agreement with GTC granting various patent rights relating to the
transgenic production of proteins, seeking, among other things, a declaratory
judgment which would effectively rescind the agreement. While the outcome of the
arbitration proceeding cannot be determined, GTC believes that there is
insufficient ground for rescission of the license agreement and that GTC will be
able to successfully defend this proceeding. There can be no assurance, however,
that GTC will prevail in the defense of the arbitration proceeding. Failure by
the Company to prevail for any reason could have a material adverse effect on
the Company, including potential delays in the commercialization of the
Company's transgenic products and increased costs.

    Dependence on Collaborators.  The success of GTC's transgenic protein
production business will depend, in large part, on GTC's ability to enter into
arrangements with biotechnology and pharmaceutical companies for the transgenic
production of proteins to which such companies have proprietary rights or to
fund the development of transgenic proteins which are in the public domain or
the subject of expiring patents. To date, the scope of these agreements has
generally been limited to demonstrating the feasibility of transgenic production
of targeted proteins in particular animal species. There can be no assurance
that these feasibility studies will be successful or lead to agreements for the
commercial production of any proteins. Depending upon the terms of any future
collaborations, the Company's role in such collaborations may be limited to the
production aspects of the proteins under development. As a result, GTC may also
be dependent on collaborators for other aspects of the development, preclinical
and clinical testing, regulatory approval and commercialization of any
transgenic product.

    Dependence on Genzyme . GTC has entered into a number of contractual
agreements with Genzyme, including a research and development agreement pursuant
to which Genzyme provides purification services to GTC for transgenically
produced proteins (the "Genzyme R&D Agreement"), a lease of GTC's facility in
Framingham, Massachusetts, and an agreement to fund the development of AT-III
through the first quarter of 1997.
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    Under the Genzyme R&D Agreement, Genzyme is obligated to use commercially
reasonable efforts to perform purification services for GTC. GTC does not
currently have personnel capable of undertaking such purification services.
Until such time, if ever, as GTC develops its own capabilities in this regard,
 there can be no assurance that Genzyme will be able to provide such services
when and as required by GTC or that GTC would be able to obtain comparable
services elsewhere.

    There can be no assurance that Genzyme and GTC will reach agreement to
extend Genzyme's funding of the AT-III development program beyond the first
quarter of 1997 under terms attractive to GTC, if at all. There also can be no
assurance that, in the absence of such agreement, the Company will be able to
fund such program on its own beyond the end of 1997 or that the Company will be
able to obtain such funding from a third party on acceptable terms, if at all.

    Potential Conflicts of Interest with Genzyme.  Genzyme is the largest single
stockholder of GTC. Assuming exercise of a currently exercisable warrant for
145,000 shares of Common Stock, Genzyme beneficially owns approximately 44% of
the outstanding Common Stock of GTC.

    Genzyme's ownership interest gives it significant influence over any
election of directors and any other action requiring approval by the holders of
a majority of the Common Stock. Three members of GTC's Board of Directors,
including Henri Termeer, the Chairman of the Board of the Company, also serve as
directors and/or executive officers of Genzyme. The interests of Genzyme on the
one hand and GTC on the other hand may, from time to time, differ.

    Risk of Service or Product Liability . GTC's business exposes it to
potential product and professional liability risks which are inherent in the
testing, production, marketing and sale of human therapeutic products. While GTC
has obtained product and professional liability insurance under an insurance
policy arrangement with Genzyme and Genzyme's affiliates, there can be no
assurance that such insurance will be sufficient to cover any claim. Uninsured
product or service liability could have a material adverse effect on the
financial results of GTC. In addition, there can be no assurance that any
insurance will provide GTC with adequate protection against potential
liabilities. Potential liability also may arise from the handling by GTC of
clinical samples containing human blood and tissues, which may contain human
pathogens; liability may also arise from handling animal blood and tissue which
may contain zoonotic pathogens. Although such products are used only in the
laboratory, inadvertent human contact may occur.

    Public Concerns.  Certain of GTC's activities involve animal testing and
genetic engineering in animals. Such activities have been the subject of
controversy and adverse publicity. Animal rights groups and various other
organizations and individuals have attempted to stop animal testing and genetic
engineering activities by pressing for legislation and regulation in these
areas. To the extent the activities of such groups are successful, GTC's
business may be adversely affected.

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