Significant improvement in Fabry disease podocytopathy after 3 years of treatment with agalsidase beta

Background Fabry disease is an X-linked lysosomal disorder caused by decreased activity of alpha-galactosidase A (GLA). Consequent accumulation of globotriaosylceramide (GL-3) in lysosomes results in damage to a variety of organs, including the kidneys. Enzyme replacement therapy (ERT) is an effective treatment, but whether it should be started before organ damage is evident is a matter of debate. A 10-year-old boy who complained of severe sole pain for 3 years had been misdiagnosed with juvenile idiopathic arthritis. Further investigations revealed decreased GLA activity and a M1T mutation in the GLA gene causing protein truncation, suggestive of Fabry disease. Despite normal renal function and urinalysis, renal biopsy showed abnormal structure, with marked accumulation of GL-3 in podocytes, partial effacement of foot processes and irregularly reduced expression of nephrin in the slit diaphragm. After 1 year of ERT with 1 mg/kg agalsidase beta once every 2 weeks, his pain had resolved with ERT combined with carbamazepine and pregabalin. After 3 years of the ERT, repeat biopsy showed little renal GL-3 deposition, resolution of foot process effacement, and a dramatic improvement in nephrin expression. There may be a window of opportunity in which pain and renal injury can be addressed in the early stages of Fabry disease. Early initiation of ERT should therefore be considered for children with Fabry disease.