Phenotype and genotype of Dent's disease in three Chinese boys.

AIM: Dent's disease represents a group of hereditary renal tubular disorders mainly characterized by hypercalciuria, nephrocalcinosis and low molecular weight proteinuria. The majority of patients with Dent's disease were found to carry CLCN5 gene mutations, whereas a small fraction of patients carry OCRL1 gene mutations. Up to date, over 100 patients with Dent's disease have been reported to carry CLCN5 gene mutations, but none in Chinese patients. The purpose of this study was to investigate the phenotypes and genotypes of three Chinese boys with Dent's disease.

METHODS: Three patients from three unrelated families were studied. Genomic DNA was extracted from peripheral white blood cells using a simple salting out procedure after informed consent. Thirteen pairs of primers were used to amplify all coding exons and exon-intron boundaries of the CLCN5 gene by polymerase chain reaction (PCR). All PCR products were sequenced directly on an autosequencer.

RESULTS: Low molecular weight proteinuria and hypercalciuria were found in all patients, nephrocalcinosis in two patients and hypophosphataemia in two patients. Three mutations of the CLCN5 gene were revealed, including R467X, L594fsX595 and R637X. Each mutation was inherited from maternal DNA, respectively. The mutation L594fsX595 was never reported before.

CONCLUSION: Low molecular weight proteinuria and hypercalciuria were the main clinical features of the three Chinese boys with Dent's disease. Our study was the first to demonstrate CLCN5 gene mutations in Chinese patients with Dent's disease and we reported a novel mutation.