To investigate the mutations of arginine vasopressin receptor 2 (AVPR2) gene in congenital nephrogenic diabetes insipidus (NDI) patients.
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.
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.
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.