Associations of genetic polymorphisms of the vitamin D pathway with blood pressure in a Han Chinese population

Vitamin D deficiency can lead to high blood pressure. Polymorphisms in the vitamin D hydroxylase gene have been associated with serum vitamin D levels in some Western countries. The aim of this study was to investigate whether polymorphisms of hydroxylase genes in the vitamin D metabolic pathway contribute to hypertension by affecting serum vitamin D status in a Han Chinese population. We selected four single nucleotide polymorphisms (SNPs; rs1993116 and rs10741657 of CYP2R1; rs4809957 and rs6068816 of CYP24A1) for genotyping in 525 control subjects and 324 hypertensive patients, and detected vitamin D levels in blood in subsets of these groups. The results showed that rs1993116 and rs10741657 were associated with a reduced risk of hypertension. The odds ratios, 95% confidence intervals, and p values from the adjusted additive and dominant models were 0.788 (0.644-0.963, p = 0.02) and 0.719 (0.545-0.949, p = 0.02) for rs1993116 and 0.805 (0.66-0.983, p = 0.033) and 0.733 (0.556-0.966, p = 0.028) for rs10741657. A protective effect of CYP2R1 with regard to hypertension was also found in males and non-smokers. The TT genotypes of rs1993116 and rs10741657 were associated with significantly lower systolic blood pressure in treated hypertensive patients (both p = 0.002). No association with hypertension was found for the two SNPs of CYP24A1, and no difference in vitamin D level was found among the three genotypes of the four SNPs. Our results suggest that CYP2R1 polymorphisms are associated with a reduced risk of hypertension independent of the vitamin D level in the Han Chinese population.