Serum 25(OH)D and vitamin D status in relation to VDR, GC and CYP2R1 variants in Chinese.

Previous studies have identified several common genetic variants in VDR, GC and CYP2R1 to be associated with circulating levels of 25-hydroxyvitamin D [25(OH)D] and vitamin D deficiency in Western populations. We aimed to investigate the associations of these variants with serum levels of 25(OH)D and vitamin D status in 1,199 Chinese. Nine common variants of VDR, GC and CYP2R1 were genotyped using multiple SNaPshot assay, and serum 25(OH)D was detected by radioimmunoassay. The prevalence of vitamin D deficiency (<50 nmol/L) was 38.8%, which is higher in women (46.2%) than in men (34.3%, P<0.0001). The risk alleles of three common variants of GC (rs7041, rs4588, and rs2282679) were significantly associated with a lower serum levels of 25(OH)D (-1.789 <=beta <=-3.549, P <= 0.006), while common variants in VDR and CYP2R1 were not associated with serum levels of 25(OH)D after adjusted for covariates (P >= 0.30). None of the nine common variants were associated with the presence of vitamin D deficiency in multivariable adjusted logistic regression analyses (P >= 0.17). Haplotype-based analyses of GC-rs7041 and rs4588 showed that the haplotype Gc2-2 (rs7041 AA and rs4588 TT) had the lowest levels Of 25(OH)D compared with other haplotypes that contained at least one copy of Gc1 allele (Ptrend<0.0001). Our results suggest that the common variants of GC are genetic determinants of serum 25(OH)D in Chinese.