OUTCOME MEASURES: The pharmacodynamic parameter to be assessed is plasma globotriaosylceramide (Gb3). The hypothesis to be tested is the role that frequency (weekly) and/or dose (0.1 to 0.4 mg/kg) of Replagal will play in pharmacodynamics as measured by reductions in plasma Gb3 compared to the current dose and frequency of 0.2 mg/kg given every two weeks. Clinical parameters including sweating, heart rate variability, proteinuria, severity of neuropathic pain, pain and anti-diarrheal medication usage, frequency and severity of abdominal pain, and frequency of diarrhea also will be assessed.