Fabry's disease discovered with chance urinary mulberry cells: a case report

Fabry's disease (FD) is a rare X-linked lysosomal storage disorder. Novel enzyme replacement therapy (ERT) at an early stage can slow the progression of cardiovascular and renal dysfunction. Urinary mulberry cells are occasionally found in renal FD. We report a case of variant FD in which detection of urinary mulberry cells led to an early diagnosis. A 36-year-old Japanese man was referred to our hospital because mulberry cells had been detected during urinalysis. Proteinuria and renal dysfunction were not observed. His plasma alpha-galactosidase activity was very low. Renal biopsy revealed typical foamy changes in the glomerular podocytes and tubular epithelial cells that are found in renal FD. Based on the detection of urinary mulberry cells, we successfully started ERT before the patient's renal function deteriorated. Clinical nephrologists and laboratory technicians should recognize the importance of screening for mulberry cells during urinalysis as this is a simple, inexpensive, and non-invasive method for diagnosing FD.