Tumor necrosis factor alpha gene polymorphism contributes to pulmonary tuberculosis susceptibility: evidence from a meta-analysis

This study is to estimate the association between polymorphisms in the tumor necrosis factor alpha (TNF-alpha) gene and pulmonary tuberculosis susceptibility (pTB). Studies were identified by searching PubMed and ISI web of Knowledge. The strength of association between the TNF-alpha gene and pTB susceptibility was assessed by odds ratios. Totals of 18 studies including 2, 735 cases and 3, 177 controls were identified referring to four single-nucleotide polymorphisms:-308G> A,-863C> A,-857C> T and-238G> A. The significantly associations were found between-308G> A (Dominant model: OR 0.53, 95% CI 0.35-0.81, P= 0.004; Homozygote model: OR 0.51, 95% CI 0.33-0.78, P= 0.002),-238G> A (Dominant model: OR 0.33, 95% CI 0.18-0.57, P< 0.001) and pTB susceptibility. The results showed that the variant genotype of TNF-alpha-308G> A was protective in pooled groups of patients with pTB in the dominant genetic model (OR 0.16, 95% CI 0.06-0.39, P< 0.001), the homozygote comparison (OR 0.14, 95% CI 0.06-0.36, P< 0.001) in African, while that was with-238G> A in the dominant genetic model (OR 0.31, 95% CI 0.18-0.56, P< 0.001) in Asian. Our meta-analysis suggest TNF-alpha-308G> A and-238G> A polymorphisms increases the risk of pTB susceptibility regardless of ethnicity and HIV statue. In Asian population, the significantly association with pTB is TNF-alpha-238G> A, while TNF-alpha-308G> A is in African population.