OCRL1 mutations in patients with Dent disease phenotype in Japan.

Three distinct OCRL1 mutations in three patients with the Dent disease phenotype are described. All the patients manifested an extremely high degree of low-molecular-weight proteinuria and showed no ocular abnormalities or apparent mental retardation. Urinalysis and blood chemistry showed no findings suggestive of Fanconi syndrome with renal tubular acidosis. Mutations in CLCN5 were ruled out. The mutations identified in OCRL1 are one frame-shift mutation (I127stop) and two missense mutations (R301C and R476W). R301C and R476W mutations might be hot spots in OCRL1, which develop very similar phenotypes as Dent-2.