Evaluating the association between taqi variant of vitamin D receptor gene and susceptibility to tuberculosis: A meta-analysis

Objectives: Vitamin D has been shown to hamper the growth of Mycobacterium tuberculosis in macrophages. The actions of vitamin D are exerted through a vitamin D receptor (VDR). The genetic variant TaqI of VDR has been implicated in tuberculosis (TB) risk in several case-control studies. However, these studies have shown inconsistent results. Hence, a meta-analysis was conducted to investigate the potential relationship between VDR TaqI polymorphism and risk of developing TB. Materials and Methods: We performed a quantitative synthesis for published studies based upon the relationship between TaqI polymorphism and TB risk from PubMed (Medline) and Embase databases. The meta-analysis was performed and pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for all genetic models. Results: A total of 21 studies including 2,960 TB cases and 3,894 controls were included in this study. The pooled analysis demonstrated no evidence of association between VDR TaqI genotypes and risk of TB in any of the genetic models; variant (t vs T: P = 0.618; OR = 1.051, 95% CI = 0.864-1.278), homozygous (tt vs TT: P = 0.120; OR = 1.336, 95% CI = 0.927-1.924), heterozygous (Tt vs TT: P = 0.925; OR = 0.988, 95% CI = 0.774-1.262), dominant model (tt + Tt vs TT: P = 0.805; OR = 1.032, 95% CI = 0.805-1.322), and recessive model (tt vs TT + Tt: P = 0.180; OR = 1.229, 95% CI = 0.909-1.660). No publication bias was detected during the analysis. Conclusions: Overall findings of this meta-analysis suggest that genetic polymorphism TaqI of VDR gene may not contribute to the risk of TB. However, future larger studies with group of populations are warranted to analyze this relationship.