Fabry disease: recent advances in enzyme replacement therapy

Fabry disease is an X-linked inherited disorder of metabolism due to mutations in the gene encoding a-galactosidase A, a lysosomal enzyme. The enzymatic defect leads to the systemic accumulation of incompletely metabolised glycosphingolipids, primarily globotriaosylceramide, in plasma and lysosomes within various tissues. Inability to prevent the progression of glycosphingolipid deposition causes significant morbidity, associated with significant impact on quality of life and diminished lifespan from early onset strokes, heart attack and progressive renal failure. The disease manifests primarily in hemizygous males; however, there is increasing recognition that heterozygous (carrier) females may also develop disease-related complications. Indeed, most heterozygotes present with cardiac, renal or neurological symptoms, although with later-onset and to a lesser extent than is observed in hemizygotes. Until recently, medical management was symptomatic, consisting of partial pain relief with analgesic drugs (carbamazepin, gabapentin), kidney and vascular protection with angiotensin-converting enzyme inhibitors, statins and folic acid, whereas renal transplantation or dialysis is available for patients experiencing end stage renal failure. The ability to produce high doses of a-galactosidase A has opened the way to preclinical studies, and enzyme replacement therapy has recently been validated as a therapeutic agent in clinical trials. Long-term safety and efficacy of replacement therapy are currently being investigated. Increasing knowledge of the natural history of Fabry disease and greater experience with enzyme therapy should enable optimal patient care. The complexity and relative rarity of Fabry disease necessitates a multi-disciplinary team approach that may be facilitated by a disease registry.