Dent disease is an X-linked recessive proximal tubular disorder that affects mostly male patients in childhood or early adult life, caused by mutations in CLCN5 (Dent disease 1) or OCRL (Dent disease 2) genes, respectively. It presents mainly with hypercalciuria, low-molecular-weight proteinuria, nephrocalcinosis and progressive renal failure. We report here the same CLCN5 mutation but different phenotypes in two Chinese brothers, and speculate on the possible reasons for the variability of the genotype-phenotype correlations.