During this 6 to 12-month study, participants will receive a 40-minute intravenous (IV) infusion of Replagal every other week, with close monitoring during and after the infusions. Before the first infusion, patients will be evaluated with a medical history, physical and neurological examinations, electrocardiogram (ECG), routine blood and urine tests, kidney test, and measurements of height, weight, and vital signs (blood pressure, pulse, breathing rate, temperature). In addition, they will have pharmacokinetic studies immediately before and following the first infusion of Replagal. For these studies, blood samples of less than a teaspoon each will be drawn to measure the level of Replagal enzyme activity. The samples will be collected at the following time points: immediately before the infusion; 20 minutes into the infusion; at the end of the infusion; after the infusion at 50, 60, and 90 minutes, and 2, 3, 4, and 8 hours.