Background: Fabry disease is a rare X-linked hereditary disorder (Xq22) caused by a deficiency in alpha-galactosidase (α-GAL) activity. This enzyme deficit results in the systemic accumulation of glycophospholipids, leading to multi-organ failure including the heart, kidneys, and brain. Enzyme replacement therapy (ERT) improves the prognosis of patients with Fabry disease. We describe a case showing progressive renal failure despite ERT. Case presentation: An 18-year-old obese male patient (body mass index (BMI) 29.9 kg/m2) was admitted for detailed examination of mild degree hypertension (150/65 mmHg) and proteinuria occurring for 2 years prior to admittance. Laboratory tests revealed mostly normal kidney function (serum creatinine 0.5 mg/dL, estimated glomerular filtration rate 181 mL/min/m2) with low α-GAL activity, a significant level of proteinuria (0.5-1.0 g/day), and the presence of mulberry cells in the urinary sediment. Renal biopsy demonstrated marked glomerulomegaly with diffuse vacuolization of the glomerular epithelial cells and focal segmental glomerulosclerosis. Electron microscopy revealed typical zebra bodies in the glomerular epithelial cells and effacement of foot processes of the epithelium. We could not find any cause of glomerulomegaly except for obesity. α-GAL gene analysis revealed a missense mutation in R301Q. Although ERT with agalsidase α was initiated, his renal function declined, and hemodialysis was initiated at 22 years of age. Conclusions: We present a case of rapid progression of Fabry nephropathy despite ERT. As with other renal diseases, obesity may aggravate the progression of Fabry nephropathy.
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