The association between single nucleotide polymorphism in vitamin D receptor and calcium oxalate urolithiasis in dogs

Background Polymorphisms of the vitamin D receptor (VDR) are associated with calcium oxalate (CaOx) nephrolithiasis in humans. Objectives To investigate the association between VDR polymorphisms and susceptibility to CaOx urolithiasis in dogs. Animals Thirty-five dogs with CaOx urolithiasis were compared with 40 stone-free dogs. Methods This was a case-control study. Two VDR gene polymorphisms (rs851998024 and rs852900542) were detected by specific TaqMan real-time polymerase chain reaction assay, and their relationship with serum 1,25-dihydroxyvitamin D, serum and urinary electrolyte concentrations was evaluated. Results The distribution of the rs852900542 polymorphism was significantly different between the case and the control dogs (x(2) = 6.369, P = .04). Dogs with a CC or CT genotype had an increased risk of CaOx stones than those with the TT genotype (odds ratio = 3.82, 95% confidence interval 1.04-13.98). The CaOx dogs with the TT genotype had a significantly lower urinary calcium-to-creatinine ratio than the CT+CC genotypes. 1,25-(OH)2D concentrations did not differ between the cases and the controls (308.7 +/- 217.4 vs 286.7 +/- 185.1 pg/mL, P = .45). Conclusions and Clinical Importance This finding suggests that vitamin D metabolism might play a role in CaOx stone formation in dogs.