Associations of TNF-α -238G/A, TNF-α -308G/A, and IL-6 -174G/C polymorphisms with the risk of asthma: Evidence from a meta-analysis

Abstract

Background: Previously, many genetic epidemiological studies have investigated associations between Th1-related cytokine polymorphisms and the risk of asthma, with inconsistent results. Accordingly, we carried out a meta-analysis to more precisely estimate associations between Th1-related cytokine polymorphisms and the risk of asthma. Methods: Systematic literature searching of Medline, Embase, Wanfang, VIP, and CNKI was conducted by the authors to identify eligible publications, and 69 genetic epidemiological studies were finally found to be eligible for quantitative analyses. Results: We found that genotypic frequencies of TNF-α -238G/A (dominant comparison: odds ratio [OR] = 0.47, P =.006; overdominant comparison: OR = 1.87, P =.03; allele comparison: OR = 0.50, P =.004), TNF-α -308G/A (dominant comparison: OR = 0.76, P =.001; overdominant comparison: OR = 1.29, P =.002; allele comparison: OR = 0.81, P =.0009) and IL-6 -174G/C (dominant comparison: OR = 0.55, P =.0008) polymorphisms among patients with asthma and control subjects were significantly different. However, we did not detect such a genotypic distribution difference for the IL-1B−511C/T polymorphism. Conclusions: The present meta-analysis shows that TNF-α -238G/A, TNF-α -308G/A, and IL-6 -174G/C polymorphisms may influence the risk of asthma.