IFN-γ +874 A>T (rs2430561) gene polymorphism and risk of pulmonary tuberculosis: A meta-analysis

Introduction: The role of interferon gamma (IFN-γ) +874 A>T (rs2430561) gene polymorphism has been evaluated in different ethnicities with pulmonary tuberculosis (PTB) infection, and inconsistent results have been reported. In this study, a meta-analysis was performed to determine the precise association between IFN-γ +874 A>T gene polymorphism and PTB susceptibility. Material and methods: A total of 21 studies comprising 4281 confirmed PTB cases and 5186 healthy controls were included in this meta-analysis by searching the PubMed (Medline), EMBASE, and Google Scholar web-databases. Results: We observed reduced risk of PTB in allelic contrast (T vs. A: P = 0.001; OR = 0.818, 95% CI: 0.723-0.926), homozygous (TT vs. AA: P = 0.017; OR = 0.715, 95% CI: 0.543-0.941), heterozygous (AT vs. AA: P = 0.002; OR = 0.782, 95% CI: 0.667-0.917), dominant (TT+AT vs. AA: P = 0.002; OR = 0.768, 95% CI: 0.652-0.906), and recessive (TT vs. AA+AT: P = 0.042; OR = 0.802, 95% CI: 0.649-0.992) genetic models. In ethnicity-wise subgroup analysis, reduced risk of PTB was found in the Caucasian population. However, we did not find an association with any of the genetic models in the Asian population. Conclusions: In conclusion, the IFN-γ +874 A>T gene polymorphism is significantly associated with reduced risk of PTB, showing a protective effect in the overall and in the Caucasian population. However, this polymorphism is not associated with PTB risk in the Asian population.