Vitamin D receptor gene polymorphisms and the risk of multiple sclerosis: An updated meta-analysis.

Background The association between vitamin D receptor (VDR) gene polymorphisms and multiple sclerosis (MS) has been extensively studied, but results were controversial. Methods This meta-analysis aimed to confirm whether VDR gene polymorphisms were associated with MS. Meta-analysis on the association between MS and VDR Apa I, Bsm I, Taq I and Fok I polymorphisms were conducted using allelic contrast, recessive, homozygotes and dominant models. Data were extracted by standardized forms and odds ratios (OR) with 95% confidence intervals (CI) were calculated using the random effects model if the results were heterogeneous. Stratification analysis by the selected study characteristics were performed to detect potential source of heterogeneity. Results A total of 21 relevant studies involving 3593 MS patients and 3917 controls were included in the analysis. The association between Taq I polymorphism and MS risk was significant in the homozygous model (p = 0.006) indicated a significant protective effect of TT Taq I genotype. High latitude (40.1–50°N) was also found markedly influenced Taq I polymorphism and MS risk in the recessive and homozygous models (p = 0.045 and p = 0.015, respectively). Additionally, Asian or low latitude (20.1–30°N) people with Apa I homozygous genotype, ‘> 2013’ publication year people in the allele contrast and dominant models of Fok I, ‘> 40 years’ age people with Bsm I recessive model also indirectly significantly affected the association between VDR gene polymorphisms and MS risk. Conclusion Taq I polymorphism is a significant protective factor for MS. However, the associations between Apa I, Fok I and Bsm I polymorphisms and MS were found only by study characteristics. [ABSTRACT FROM AUTHOR]