CLONING AND CHARACTERIZATION OF CLCN5, THE HUMAN KIDNEY CHLORIDE CHANNEL GENE IMPLICATED IN DENT DISEASE (AN X-LINKED HEREDITARY NEPHROLITHIASIS)

Dent disease, an X-linked familial renal tubular disorder, is a form o f Fanconi syndrome associated with proteinuria, hypercalciuria, nephro calcinosis, kidney stones, and eventual renal failure. We have previou sly used positional cloning to identify the 3' part of a novel kidney- specific gene (initially termed hClC-K2, but now referred to as CLCN5) , which is deleted in patients from one pedigree segregating Dent dise ase. Mutations that disrupt this gene have been identified in other pa tients with this disorder. Here we describe the isolation and characte rization of the complete open reading frame of the human CLCN5 gene, w hich is predicted to encode a protein of 746 amino acids, with signifi cant homology to all known members of the ClC family of voltage-gated chloride channels. CLCN5 belongs to a distinct branch of this family, which also includes the recently identified genes CLCN3 and CLCN4. We have shown that the coding region of CLCN5 is organized into 12 exons, spanning 25-30 kb of genomic DNA, and have determined the sequence of each exon-intron boundary. The elucidation of the coding sequence and exon-intron organization of CLCN5 will both expedite the evaluation o f structure/function relationships of these ion channels and facilitat e the screening of other patients with renal tubular dysfunction for m utations at this locus. (C) 1995 Academic Press, Inc.