Genetic variant in vitamin D binding protein is associated with serum 25-hydroxyvitamin D and vitamin D insufficiency in southern Chinese

Previous large-scale genome-wide meta-analysis identified four loci affecting 25-hydroxyvitamin D (25(OH)D) concentrations. However, whether these loci are associated with 25(OH)D concentration in southern Chinese remain unknown. Our primary aim was to examine whether the four top hits (rs2282679, rs10741657, rs12785878 and rs6013897) could be replicated in 712 southern Chinese women. The associations between these single-nucleotide polymorphisms (SNPs), serum 25(OH)D concentration (continuous variable) and vitamin D insufficiency (dichotomized variable) were examined using multivariable linear regression and logistic regression, respectively. Age, body mass index and season were adjusted in the model. Among these four SNPs, rs2282679 was associated with serum 25(OH)D levels (beta = -0.066; P = 9 x 10(-5)) and vitamin D insufficiency (odds ratio (OR) = 1.51, 95% confidence interval (CI) 1.19-1.93; P = 8.6 x 10(-4)), whereas rs12785878 was nominally associated with vitamin D insufficiency only (OR = 0.79, 95% CI 0.63-0.99; P = 0.042). Genotype risk score (GRS), by summing risk variants of these two SNPs, had more significant association with vitamin D insufficiency (OR = 1.38; 95% CI 1.17-1.64; P-trend = 1.76 x 10(-4)) than the model that included only either SNP. The areas under receiver operating characteristic curves of rs2282679 and GRS were 0.561 (P = 0.005) and 0.576 (P = 5 x 10(-4)), respectively. Our study provides an independent evidence of the associations of rs2282679 and probably rs12785878 with 25(OH)D and vitamin D insufficiency in southern Chinese.