title: Association of interleukin-13 C-1112T and G+2044A polymorphisms with asthma: a meta-analysis.
abstract: OBJECTIVE
  Polymorphisms in the IL13 gene have been reported to be associated with susceptibility to asthma. However, a number of studies have shown inconsistent results. A meta-analysis was performed to investigate whether polymorphisms in the IL13 gene were associated with the risk of asthma.
  
  
  METHODS
  Searches were performed of the Medline and Chinese National Knowledge Infrastructure (CNKI) databases, covering all papers published up to 31 August 2010. A recently proposed logistic regression-based method for meta-analysis of case-control genetic association studies was used to analyse pooled data. All statistical analyses were performed using stata version 10.0 software.
  
  
  RESULTS
  The IL13 C-1112T and G+2044A polymorphisms were investigated in 10 and 14 studies, respectively. The summary estimates suggested that both these polymorphisms were associated with susceptibility to asthma. Carriers of the IL13 -1112T allele had a 38.9% increased risk of asthma compared with homozygotes (-1112CC) (odds ratio (OR) 1.389, 95% confidence interval (CI): 1.103-1.749). Carriers of the IL13+2044A allele had a 40.0% increased risk of asthma compared with homozygotes (+2044GG) (OR 1.400, 95% CI: 1.137-1.724). In a subgroup analysis by ethnicity, the IL13 -1112T allele was associated with an increased risk of asthma among Caucasians (OR 1.629, 95% CI: 1.255-2.113) but not among Asians, and the IL13+2044A allele was associated with an increased risk of asthma among Asians (OR 1.436, 95% CI: 1.101-1.873) but not among Caucasians.
  
  
  CONCLUSIONS
  This meta-analysis indicated that the IL13 C-1112T and G+2044A polymorphisms predispose to asthma. Further studies, including pooling of individual data to facilitate evaluation of gene-gene and gene-environment interactions between these IL13 gene polymorphisms and asthma susceptibility, are recommended.
authors.affiliation: National Institute for Occupational Health and Poison Control, Key Laboratory of Chemical Safety and Health, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Yang
authors.forename: Haiyan
authors.initials: H
authors.lastname: Dong
authors.forename: Yufei
authors.initials: Y
authors.lastname: Dai
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D001249:Asthma / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics*; D002681:China / Q000453:epidemiology; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D018793:Interleukin-13 / Q000235:genetics*; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
chemical_list: D018793:Interleukin-13