Associations study of vitamin D receptor gene polymorphisms with diabetic microvascular complications: a meta-analysis

Background: Emerging evidence from preclinical and clinical studies has shown that vitamin D plays an important role in the pathogenesis of diabetic microvascular complications (DMI). Several potentially functional polymorphisms (ApaI, BsmI, FokI and TaqI) of vitamin D receptor (VDR) gene have been implicated in DMI risk, but individually published studies showed inconclusive results. The aim of this study was to quantitatively summarize the association between VDR polymorphisms and DMI risk. Methods: We searched all the publications about the associations mentioned as above from PubMed and ISI database updated in December 2013. Meta-analysis of the overall odds ratios (ORs) with 95% confidence intervals (Cls) was calculated with the fixed or random effect model. Results: Eight studies involving 2734 subjects were included. Allelic and genotypic comparisons between cases and controls were evaluated. Overall analysis suggests that no significant association was observed among the ApaI, Bsml, Fold and TaqI variants and DMI risk in diabetic patients (all P values >0.05). In the stratified analysis, significant association was observed with diabetic nephropathy (DN) for VDR gene Fold polymorphism under a dominant model (OR 135, 95% CI 1.05-1.74, P = 0.02) in Caucasians. Conclusions: This meta-analysis indicated that the FokI polymorphism in VDR gene might affect individual susceptibility to DN in Caucasians. Further investigations are needed to confirm our results. (C) 2014 Elsevier B.V. All rights reserved.