Association of IFN-γ and IFN regulatory factor 1 polymorphisms with childhood atopic asthma

Background: IFN-gamma and related molecules play important roles in the differentiation and function of T(H)2 cells. Objective: We sought to determine whether IFNG and related genes contribute to any susceptibility to atopic asthma, a representative T(H)2-dominant disorder. Methods: We investigated the association of IFNG (CA repeat polymorphism within the first intron), IRF1 (GT repeat polymorphism within the intron 7), IFNGR1 (Val 14 Met), and IFNGR2 (Gln 64 Arg) gene polymorphisms with atopic asthma in the Japanese child population. Results: A significant association (P = .0018) was observed between IFNG gene polymorphism and atopic asthma. The tendency was more prominent in patients with age of onset of 3 years or younger (P = .0004) or patients with a family history of allergic diseases (P = .0038). Furthermore, there was a significant association between IRF1 gene whole-allele distribution and atopic asthma (P = .014). The tendency was more prominent in patients with onset at 3 years of age or less (P = .0058). On the other hand, IFNGR1 and IFNGR2 gene polymorphisms showed no association with atopic asthma. Conclusion: These results suggested that among IFNG and related genes, IFNG and IRF1 genes confer genetic susceptibility to atopic asthma in Japanese children.