A number of studies have reported that the interleukin 13 (IL-13) gene is associated with asthma susceptibility. However, the reported relationships between the +2044G/A and +1923C/T polymorphisms and asthma susceptibility are inconsistent, especially in Asian adults and children with atopic status. Meta-analysis was used to analyze combined data.
The +2044G/A and +1923C/T polymorphisms were investigated using data from 18 and 11 studies, respectively. The results suggested that there was an association between asthma and the IL-13 +2044G/A polymorphisms: odds ratio (OR) 1.34, 95% confidence interval (CI) 1.03–1.75 for AA versus GG + GA and +1923C/T; OR 1.50, 95% CI 1.26–1.78 for TT versus CC; and OR 1.15, 95% CI 1.10–1.21 for TC versus CC. The subgroup meta-analysis demonstrated that IL-13 +2044G/A polymorphisms are associated with asthma: OR 1.47, 95% CI 1.06–2.04 for AA versus GG + GA and +1923C/T; OR 1.70, 95% CI 1.26–2.30 for TT versus CC; and OR 1.27, 95% CI 1.03–1.56 for TC versus CC. In particular, IL-13 +2044G/A polymorphisms are specifically associated with Asian ethnicity in both adults and children with atopic status. However, the 1923C/T polymorphisms were not significantly associated with age group or atopic status within the Asian subgroups. Further investigation using larger samples and meta-analysis is required. No publication bias was detected.
This meta-analysis indicates that the IL13 +2044G/A and +1923C/T polymorphisms are risk factors for asthma, especially among Asians.