The interleukin-4 − 589C/T polymorphism and the risk of asthma: A meta-analysis including 7345 cases and 7819 controls

Abstract

BackgroundA number of studies assessed the association of −589C/T polymorphism in the promoter region of interleukin-4 (IL-4) with asthma in different populations. However, the results were contradictory. A meta-analysis was conducted to investigate the association between polymorphism in the IL-4 and asthma susceptibility. MethodsDatabases including Pubmed, EMBASE, Wanfang Database, China National Knowledge Infrastructure (CNKI) and Weipu Database were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. ResultsThirty-four studies involving 7345 cases and 7819 controls were included. Overall, significant association between −589C/T polymorphism and asthma was observed for TT+CT vs. CC (OR=1.26; 95% CI 1.12–1.42; P=0.0001; I2=26%). In the subgroup analysis by ethnicity, significant associations were found among Asians (OR=1.36; 95% CI 1.07–1.73; P=0.01; I2=0%) and Caucasians (OR=1.30; 95% CI 1.09–1.54; P=0.004; I2=53%) but not among African Americans (OR=1.20; 95% CI 0.72–2.00; P=0.48; I2=48%). In the subgroup analysis by atopic status, no significant association was found among atopic asthma patients (OR=1.20; 95% CI 0.92–1.34; P=0.27; I2=6%) and non-atopic asthma patients (OR=0.97; 95% CI 0.73–1.28; P=0.81; I2=0%). ConclusionsThis meta-analysis suggested that the IL-4 −589C/T polymorphism was a risk factor of asthma.