Genzyme Update on the LOTS Trial- January 2007

In an effort to complete the AGLU02704 study (Late-Onset Treatment Study,
LOTS) as responsibly as possible, Genzyme has amended the study protocol to
incorporate the use of an adaptive design. Genzyme utilized this method to
help ensure a conclusive trial outcome in this small group of participants,
and worked with regulatory agencies and study investigators to implement it.
Under this adaptive design, an independent statistical center (ISC) and the
Pompe Data Safety Monitoring Board (DSMB) examined study data to recommend a
study end date that would ensure the most robust study outcome. Genzyme,
study investigators, and study participants remain blinded to the treatment
assignments and to the ISC data analyses.

The statistical analysis occurred in late December, 2006 and the ISC and
DSMB recommended that each study participant should complete 18 months (78
weeks) of double blind treatment. Genzyme has accepted this recommendation
to end the study in September of 2007, which will allow for the collection
of sufficient data to discern a conclusive trial outcome with the greatest
statistical confidence. Based on the current enrollment, the last study
visit will be completed in September, 2007; however, some participants will
begin to reach their 18 month visit as early as March of 2007.

Study investigators and participants have been notified of these changes to
the trial design and the new timeframes. In order to complete the LOTS
trial under the adaptive design, all study participants will need to remain
in the LOTS trial for 18 months (6 months longer than the original
protocol). Investigators discussed this possibility with study participants
when the adaptive design was implemented. Genzyme is aware of the impact
this change has on participants and the clinical team has been working to
establish local infusion sites for the majority of participants.

Now that Myozyme® (alglucosidase alfa) is commercially available, there may
not be another opportunity to collect data in a controlled way to adequately
demonstrate safety and efficacy to the appropriate regulatory authorities in
order to support the full patient population. Therefore, the completion of
the study is of paramount importance for the Pompe community.

Furthermore, as a Post Marketing Commitment to the FDA, Genzyme has agreed
to complete an open-label Extension Study (AGLU03206), where all
participants will receive treatment with Myozyme, to follow the LOTS study.
Study participants who successfully complete LOTS will be eligible to roll
over into the AGLU03206 extension study as per the protocol’s
inclusion/exclusion criteria. The minimum total duration of study
participation in both LOTS and the open-label Extension Study combined is 24
months.

As with all clinical trials, when a study is completed, the final data
collection, analysis, and presentation of the results can take several
months. Data from the LOTS trial will be submitted to the appropriate
regulatory agencies worldwide. Those authorities will determine if the
safety and efficacy data can be used to update their respective prescribing
labels as appropriate.

Genzyme would like to acknowledge and thank the patient community and study
investigators for their ongoing commitment to successfully complete the LOTS
trial and their continued support of obtaining this critically important
information for the Pompe community.