Association between the vitamin D receptor gene polymorphisms and diabetic nephropathy risk: A meta-analysis.

AIMS: Diabetic nephropathy (DN) is a severe microvascular complication frequently associated with type 1 and type 2 diabetes mellitus. The objective of this study was to estimate the effect between Apa I, Bsm I, Fok I and Taq I polymorphisms of the vitamin D receptor (VDR) gene and DN susceptibility.

METHODS: Eligible case-control studies published updated to March 2017 were searched. The odds ratio (OR) and 95% confident intervals (CI) were used to calculate the strength of effect.

RESULTS: Twelve articles were finally screened out, including 3954 diabetic patients and 1248 healthy controls. When compared with the diabetic patients without nephropathy, our results found that only the Bsm I polymorphism was associated with increased risk of DN under the allelic model (B vs. b: OR = 1.51, 95% CI = 1.03-2.20, P = 0.04) and dominant model (BB + Bb vs. bb: OR = 1.52, 95% CI = 1.00-2.31, P = 0.05). When compared with the healthy controls, our results showed that the Bsm I polymorphism was associated with the DN susceptibility under the allelic model (B vs. b: OR = 1.80, 95% CI = 1.12-2.91, P = 0.02), the homogeneous model (BB vs. bb: OR = 1.43, 95% CI = 1.03-1.98, P = 0.03), and the domain model (BB + Bb vs. bb: OR = 1.80, 95% CI = 1.06-3.05, P = 0.03); the Taq I variant was associated with increased risk of DN only under the heterogeneous model (Tt vs. tt: OR = 2.29, 95% CI = 1.04-5.03, P = 0.04).

CONCLUSION: Our results suggested that B allele, and BB + Bb genotypes of Bsm I variant, Tt genotype of Taq I variant might be risk factors for DN. Future researches are still needed to identify our results.