Association between FokI, ApaI of vitamin D receptor gene polymorphism and idiopathic hypocitraturia

Objective To investigate the association between FokⅠ (rs2228570), ApaⅠ (rs7975232) of vitamin D receptor (VDR) gene polymorphism and idiopathic hypocitraturia (IH) in the Yunnan Yi population and its clinical significance in the large screening. Methods 501 cases of IH and 378 controls with normal urinary citrate were selected from the Yunnan Yi population, and the association between rs2228570 and rs7975232 VDR gene polymorphism with IH in the Yunnan Yi population was analyzed by SNaPshot detection. Results There were significant diferences in the practical fequency and expected fequency between the two single nucleotide polymorphism (SNP) sites in the hard—weinberg equilibrium (rs2228570: χ2=2.111, P>0.05; rs7975232: χ2=3.320, P>0.05). The mean urinary citrate content of 501 cases was (243.26±38.63) mg/24 h and that of 378 controls was (591.58±125.89) mg/24 h with the differences being statistically significant (t=34.263, P<0.05). There was significant difference in the genotype frequency difference of the VDR gene SNP rs2228570, rs7975232 (rs2228570: χ2=9.247, P<0.05; rs7975232: χ2=9.997, P<0.05) between cases and controls. The frequency of TT genotype (0.267) in the rs2228570 was higher than that in the control group (0.188), while the CT and CC genotype frequencies in the rs2228570 group were lower than those in the control group (χ2=9.899, P<0.05). The frequency of AA genotype (0.192) in the rs7975232 case group was higher than that in the control group (0.095), and the frequency of AA and CC genotypes in the case group was lower than that in the control group (χ2=15.696, P<0.05). The urinary citrate content of cases with rs2228570 genotype TT was significantly lower than that in those with genotype CC and genotype CT [(506.47±198.02) mg/24 h, t=6.276, P<0.05; (485.95±190.95) mg/24 h, t=4.709, P<0.05]. The urinary citrate content of cases with rs7975232 genotype AA was significantly lower than that in those with genotype CC and genotype CA [(507.67±197.42) mg/24 h, t=4.366, P<0.05; (485.55±180.15) mg/24 h, t=3.963, P<0.05]. Conclusion IH in the Yunnan Yi population has the association with rs2228570, rs7975232 VDR gene polymorphisms. Key words: Yunnan Yi population; Vitamin D receptor; Single nucleotide polymorphism; Idiopathic hypocitraturia