Genzyme Implements New HER2 Testing Guidelines

Date: March 14, 2007

Westborough, Mass. – Genzyme Genetics, the diagnostic testing division of Genzyme Corporation, recently announced the company has fully implemented the new HER2 testing practice guidelines recently recommended by the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP). These guidelines help oncologists to effectively determine an appropriate course of treatment for patients.

According to an ASCO/CAP expert panel, approximately 20% of current HER2 testing may be inaccurate. Test variation could be caused by several factors, including specimen preparation, non-standardized lab procedures, reagent variability, quality control procedures and interpretation criteria. The ASCO/CAP guidelines, which were issued to help physicians more accurately define HER2 status in breast cancer cases, provide updated methodologies and quality assurance measures with the express purpose of achieving more consistent results.

“Genzyme launched its first HER2 test in 1998, and today we see approximately 20% of all newly diagnosed breast cancer cases in the U.S.” says Bruce Horten, M.D., national medical director for Genzyme Genetics. “We know the impact a single test has on a treatment decision, and that is why implementing these guidelines was a priority for Genzyme.”

Results from HER2 testing help an oncologist determine the appropriate treatment for patients with breast cancer, including specific drugs that target the HER2 protein. The new guidelines are intended to help physicians provide more accurate HER2 testing results. More accurate results are critical to ensuring that patients who may benefit from the anti-HER2 antibody therapy are identified, and that patients not expected to benefit are not unnecessarily exposed to potential toxicities.

Genzyme has had industry-leading quality control and proficiency procedures in place for many years and, with the implementation of the new ASCO/CAP guidelines, its HER2 testing services remain among the best in class.

About Genzyme Genetics

Genzyme Genetics is a leading, nationwide provider of high-quality, complex testing services for physicians and their patients. With CLIA-certified laboratories and counseling facilities located across the U.S., Genzyme Genetics offers extensive diagnostic testing services, supported by innovative technology and a commitment to quality service and trusted information. Genzyme Genetics is a business unit of Genzyme Corporation.

About Genzyme Corporation

One of the world's leading biotechnology companies, Genzyme is dedicated to making a major positive impact on the lives of people with serious diseases. Since 1981, the company has grown from a small start-up to a diversified enterprise with more than 9,000 employees in locations spanning the globe and 2006 revenues of $3.2 billion. Genzyme has been selected by FORTUNE as one of the “100 Best Companies to Work for” in the United States.

With many established products and services helping patients in nearly 90 countries, Genzyme is a leader in the effort to develop and apply the most advanced technologies in the life sciences. The company's products and services are focused on rare inherited disorders, kidney disease, orthopaedics, cancer, transplant and immune diseases, and diagnostic testing. Genzyme's commitment to innovation continues today with a substantial development program focused on these fields, as well as heart disease and other areas of unmet medical need.

This press release contains forward-looking statements, including the statements regarding the ability of the ASCO/CAP guidelines to help physicians provide more accurate HER2 testing results and the ability of HER2 testing to identify patients who may or may not benefit from the anti-HER2 antibody therapy. These statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected in these forward-looking statements. These risks and uncertainties include, among others, the failure of HER2 testing under the ASCO/CAP guidelines to produce diagnostic results as anticipated, the inability for physicians to improve cancer treatment as expected notwithstanding physicians’ access to HER2 testing, the continued availability of HER2 testing resulting from the lack of commercial acceptance of this test, including the acceptance of the test at price levels that are economically viable for Genzyme Genetics, and the risks and uncertainties described in reports filed by Genzyme with the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended, including without limitation the information under the heading "Factors Affecting Future Operating Results" in the Management's Discussion and Analysis of Financial Condition and Results of Operations section of the Genzyme Annual Report on Form 10-K for the year ending December 31, 2006. Genzyme cautions investors not to place substantial reliance on the forward-looking statements contained in this press release. These statements speak only as of the date of this press release, and Genzyme undertakes no obligation to update or revise the statements.

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