Influence of BsmІ polymorphism in vitamin D receptor gene on the risk of fracture in Caucasian populations: a meta analysis

Objective: To gain combined risk estimates for the BsmІ polymorphism in vitamin D receptor (VDR) gene associated with the risk of fractures in Caucasian population. Methods: We performed a meta-analysis and extracted 15 eligible publications by searching the databases of Medline, EMBASE and CNKI. Summary odds ratio (OR) with 95% confidence interval (CI) was estimated by using fixed-effects model. The inconsistency index (I2) was performed to evaluate heterogeneity. Begg’s funnel plots and Egger’s test were used to assess publication bias. Results: A total of 15 available studies including 5,570 subjects (1,912 cases and 3,658 controls) were included in the meta-analysis. No overall association was observed between the BsmI polymorphism in VDR gene and the susceptibility to fracture under all genetic models. When stratifying by fracture type, we did not find any significant risk, either. But in the subgroup analysis by source of control, the results from population-based groups suggested the BsmI polymorphism was associated with the increased fracture susceptibility (ORBB vs. bb = 1.22, 95% CI = 1.011.48, Pheterogeneity = 0.912; ORB vs. b = 1.10, 95% CI = 1.00-1.20, Pheterogeneity = 0.921). Conclusions: Our meta-analysis provides evidence that the BsmI polymorphism in VDR gene may not be associated with the susceptibility to fracture in Caucasian populations. Our findings need to be further confirmed in future larger and well-designed studies.