This study will determine the safety and effectiveness of the drug Replagal for treating people with Fabry disease, an inherited metabolic disorder. In this disease, an enzyme called alpha-galactosidase A, which normally breaks down a lipid (fatty substance) known as ceramidetrihexoside, is missing or does not function properly. As a result, the lipid accumulates in the body, causing problems with the kidneys, heart, nerves, and blood vessels. This study will examine whether replacing the missing alpha-galactosidase A with a genetically engineered form of the enzyme called Replagal can reverse the illness.

Patients with Fabry disease who are 18 years of age or older and have completed 10 weeks of Replagal therapy as participants in protocol TKT027 may be eligible for this 6-month study extension.

Participants undergo the following tests and procedures:

• Intravenous (IV) infusions of Replagal every other week over 25 weeks for a total of 13 infusions, with close monitoring during and after the infusions.
• Brief safety evaluations at the time of each infusion, including a check of vital signs (blood pressure, pulse, breathing rate, temperature), review of any side effects, and review of medications.
• Comprehensive evaluations at baseline (before starting Replagal therapy), after 13 and 25 weeks of therapy, and 30 days after completing therapy. These include a medical history and physical examination, symptoms and pain questionnaire, blood and urine tests, check of vital signs, electrocardiogram (EKG), 2-hour Holter monitor, and sweat test (QSART).

Objectives: To evaluate the safety of the current standard Replagal treatment regimen of 0.2 mg/kg given intravenously every two weeks over an additional 6 months in patients who have completed 10 weeks of Replagal therapy in the TKT027 study.

Study Population: Hemizygous males with Fabry disease who are 18 years of age or older who have completed 10 weeks of Replagal therapy in TKT027.

Design: This is an open-label, multi-center study that will assess the safety of 0.2 mg/kg every two weeks of enzyme replacement therapy with Replagal.

INCLUSION CRITERIA:

Subject must have completed 10 weeks of infusions in Study TKT027 with intent to complete participation in the study.

Subject must have adequate general health (as determined by the investigators) to undergo the specified phlebotomy regimen and protocol related procedures.

Subject must consent to participate in the protocol and must have voluntarily signed an Institutional Review Board/Independent Ethics Committee (IRB/IEC) approved informed consent form after all relevant aspects of the study have been explained and discussed with the patient.

EXCLUSION CRITERIA:

Subject is unable to understand the nature, scope, and possible consequences of the study.

Subject is unable to comply with the protocol, e.g., uncooperative with protocol schedule, refusal to agree to all of the study procedures, inability to return for safety evaluations, or is otherwise unlikely to complete the study, as determined by the investigator or the medical monitor.