The association between the C-509T and T869C polymorphisms of TGF-β1 gene and the risk of asthma: A meta-analysis

Asthma is a complex multigenic disease in which gene–environment interactions play a critical role in disease onset and progression. Transforming growth factor-β1 (TGF-β1) is one of several candidate locus for the pathogenesis of asthma, and is highly polymorphic. To derive a more precise estimation of the relationship between the T869C and C-509T polymorphisms of the TGF-β1 gene and asthma, a meta-analysis of 24 published case–control studies was conducted. 20 studies for C-509T polymorphism and 8 studies for T869C polymorphism were included. The pooled odds ratios were calculated respectively for allele contrasts, additive genetic model, dominant genetic model and recessive genetic model. Subgroup analyses were also performed by ethnicity, age, atopic status and asthma severity for two gene polymorphisms. In regard to T869C polymorphism, significant associations with asthma were observed in recessive (OR 1.23, 95%CI 1.00–1.51 and P = 0.047), additive and allele models. In the subgroup analysis by age, significant risks were also found in the recessive model for adults (OR 1.31, 95%CI 1.02–1.69 and P = 0.032), atopic asthma (OR 1.63, 95%CI 1.07–2.49 and P = 0.023). With respect to C-509T polymorphism, significant associations with asthma were demonstrated in the overall analysis and subgroup analyses in the dominant model for Asian (OR 1.37, 95%CI 1.04–1.81 and P = 0.025), Adults (OR 1.26, 95%CI 1.02–1.56 and P = 0.035), Children (OR 1.19, 95%CI 1.01–1.40 and P = 0.034). Potentially functional TGF-β1 C-509T and T869C polymorphisms may be risk factors for asthma susceptibility.