[Identification of mutations in the arginine vasopressin receptor 2 gene in congenital nephrogenic diabetes insipidus patients].

Objective: To investigate the mutations of arginine vasopressin receptor 2 (AVPR2) gene in congenital nephrogenic diabetes insipidus (NDI) patients.
Methods: Genomic DNA was extracted from the blood samples of 7 congenital NDI patients, all males, and 24 of their family members. The 6 fragments of AVPR2 gene were amplified by PCR. The gene mutations were preliminarily screened by SSCP and further confirmed by DNA sequencing.
Results: 5 types of mutation and 8 mutant sites of AVPR2 gene were found in 6 of the 7 patients. Two cases were found to have 2 different sites of mutation in the AVPR2 gene. In 4 cases new mutation sites not reported previously in the literature, i.e., g.469-493del 24, g.541insT, g.462delC and g.935T > C, were identified, resulting in the change of AVPR2 proteins, including A37-L44del (deletion mutation), A61G 190X (insertion frame-shift and nonsense mutation), P34R 36X (deletion frame-shift and nonsense mutation) and C192R (missense mutation). Among the 24 family members examined only one, a mother, was found to have an AVPR2 gene mutation with the same mutation site as the proband.
Conclusion: Four novel mutation sites have been identified in the AVPR2 gene among the congenital NDI patients. PCR-SSCP and DNA sequencing can be used to preliminarily screen and diagnose gene mutation among congenital NDI patients.