NEPHROGENIC DIABETES-INSIPIDUS - AN X-CHROMOSOME-LINKED DOMINANT INHERITANCE PATTERN WITH A VASOPRESSIN TYPE-2 RECEPTOR GENE THAT IS STRUCTURALLY NORMAL

Nephrogenic diabetes insipidus is a rare hereditary disorder, most commonly transmitted in an X chromosome-linked recessive manner and characterized by the lack of renal response to the action of antidiuretic hormone [Arg(8)]vasopressin. The vasopressin type 2 receptor (V(2)R) has been suggested to be the gene that causes the disease, and its role in disease pathogenesis is supported by mutations within this gene in affected individuals. Using the PCR, denaturing gradient gel electrophoresis, and direct DNA sequencing, we examined the V(2)R gene in four unrelated kindreds. In addition, linkage analysis with chromosome Xq28 markers was done in one large Brazilian kindred with an apparent unusual X chromosome-linked dominant inheritance pattern. In one family, a mutation in codon 280, causing a Tyr --> Cys substitution in the sixth transmembrane domain of the receptor, was found. In the other three additional families with nephrogenic diabetes insipidus, the V(2)R-coding region was normal in sequence. In one large Brazilian kindred displaying an unusual X chromosome-linked dominant mode of inheritance, the disease-related gene was localized to the same region of the X chromosome as the V(2)R, but no mutations were found, thus raising the possibility that this disease is caused by a gene other than V(2)R.