Associations of tumor necrosis factor-α polymorphisms with the risk of asthma: a meta-analysis

Objective: Recently, potential correlations between tumor necrosis factor-alpha (TNF-alpha) polymorphisms and asthma were investigated by some pilot studies, but the results of these studies were inconsistent. Therefore, we performed this meta-analysis to better evaluate the relationship between TNF-alpha polymorphisms and the risk of asthma. Methods: Eligible studies were searched in PubMed, Medline, Embase and CNKI. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess correlations between TNF-alpha polymorphisms and asthma. Results: A total of 50 studies were included for analyses. Significant associations with the risk of asthma were detected for TNF-alpha - 238 G/A, - 308 G/A and - 857C/T polymorphisms in overall analyses. Further subgroup analyses according to ethnicity of participants revealed that TNF-alpha - 238 G/A polymorphism was significantly correlated with the risk of asthma in Caucasians, TNF-alpha - 308 G/A polymorphism was significantly correlated with the risk of asthma in West Asians, TNF-alpha - 857C/T polymorphism was significantly correlated with the risk of asthma in Caucasians, TNF-alpha - 863C/A polymorphism was significantly correlated with the risk of asthma in East Asians, and TNF-alpha - 1031 T/C polymorphism was significantly correlated with the risk of asthma in Caucasians and East Asians. Conclusions: Our findings indicated that TNF-alpha - 238 G/A, - 308 G/A, - 857C/T, - 863C/A and - 1031 T/C polymorphisms may serve as potential biological markers for asthma in certain ethnicities.