Objective: To determine if GC (group-specific component globulin) and CYP2R1 genetic variants have an association with serum 25-OHD3 levels, BMD or bone turnover markers in a population of Chinese postmenopausal women.
Design: We randomly selected 1494 postmenopausal women of the Han ethnic group from seven communities in Beijing. BMD was determined by dual energy X-ray absorptiometry; serum bone turnover markers and 25-OHD3 were measured by the automated Roche electrochemiluminescence system; genotypes of GC and CYP2R1 were detected by the TaqMan allelic discrimination assay. Multiple statistic methods were used to test the associations of SNP genotypes and vitamin D levels.
Results: In our sample, 89.6% women had vitamin D deficiency and another 9.8% had vitamin D insufficiency. The variants of rs2298849 (β=0.105, P<0.001) in GC were significantly associated with serum 25-OHD3 levels. Allele G of rs2298849 might be protective for serum 25-OHD3 level. Among the haplotypes of rs222020-rs2298849, CG (β=0.104, P=0.001) corresponded to increasing serum 25-OHD3 concentrations. CYP2R1 polymorphisms showed some significant association with serum β-CTX and P1NP levels.
Conclusions: We found that GC variants had a significant association with serum 25-OHD3 levels among postmenopausal women of the Han ethnic group in Beijing, while CYP2R1 variants were not found to be significant.