Untitled

Abstract

Oculo-cerebro-renal syndrome of Lowe (Lowe syndrome), caused by mutation of OCRL1, is a rare, multisystem disorder characterized by bilateral cataracts, mental retardation, hypotonia and renal tubular abnormalities, whereas Dent disease, mainly caused by mutations in the chloride channel gene (CLCN5), is distinguished by exclusive renal tubular dysfunction resulting in low-molecular-weight proteinuria, hypercalciuria, nephrocalcinosis and urolithiasis. We encountered a 3 year-old-boy with asymptomatic tubular proteinuria and hypercalciuria. He was initially diagnosed as having Dent disease because there were no clinical and laboratory findings indicating Lowe syndrome, mitochondrial encephalopathy, interstitial nephritis or Fanconi syndrome. However, short stature, mental retardation and cataract, all of which were not observed at first visit, have developed since 6 years of age. Genomic DNA analysis for OCRL1 disclosed nonsense mutation while that for CLCN5 did not. In summary, mutation of OCRL1 should be considered and sought in children having asymptomatic tubular proteinuria who do not demonstrate extra-renal manifestations featuring Lowe syndrome.