The CTLA-4 +49 A/G and -318 C/T polymorphisms and susceptibility to asthma: a meta-analysis

The aim of this study was to explore whether cytotoxic T lymphocyte antigen-4 (CTLA-4) +49 A/G, and -318 C/T polymorphisms confer susceptibility to asthma. A meta-analysis was conducted on the associations between the CTLA-4 +49 A/G, and -318 C/T polymorphisms and asthma using; (1) allele contrast, (2) the recessive model, (3) the dominant model, and (4) the additive model. Eight studies on the CTLA-4 polymorphisms and asthma involving 2,330 patients with asthma and 1,743 control subjects were included in this meta-analysis. The meta-analysis revealed an association between asthma and the CTLA-4 +49 A/G polymorphism under the dominant model in Asians (OR = 0.758, 95 % CI = 0.599-0.958, p = 0.020). Stratification by age indicated an association between the CTLA-4 +49 GG+GA genotype and asthma in children (OR = 0.690, 95 % CI = 0.497-0.957, p = 0.026), but not in adults (OR = 0.837, 95 % CI = 0.598-1.172, p = 0.300). Furthermore, stratification by atopy status indicated an association between the CTLA-4 +49 G allele and atopic asthma (OR = 0.639, 95 % CI = 0.464-0.881, p = 0.006), but not non-atopic asthma (OR = 0.706, 95 % CI = 0.385-1.294, p = 0.266). There was no association between asthma and the CTLA-4 -318 C/T polymorphism for the whole population, or when stratified by ethnicity, age, or atopy status. This meta-analysis demonstrates that the CTLA-4 +49 A/G polymorphism confers susceptibility to asthma in Asians, children, patients with atopy status, but there was no association between the CTLA-4 -318 C/T polymorphism and asthma susceptibility.