Interleukin 13 and interleukin 4 receptor-α polymorphisms in rhinitis and asthma.

BACKGROUND Asthma and rhinitis may represent two manifestations of the same airway disease. Genetic research can increase our understanding of their common or distinct pathogenesis. IL13 and IL4R polymorphisms are associated with asthma and show gene-gene interaction in asthma. Their role in rhinitis has not been extensively studied. METHODS Association of IL13 and IL4R polymorphisms in relation to rhinitis, asthma, serum IgE and skin test response was studied in: (1) 188 trios ascertained through a proband with rhinitis who were clinically not affected by asthma; (2) 407 trios with an asthmatic proband, and (3) 118 asthma cases and 102 unrelated healthy controls using family-based association testing, logistic regression, and analysis of variance as appropriate. Gene-gene interaction was evaluated using logistic regression analysis. RESULTS IL13 C-1111T (rs1800925) was significantly associated with rhinitis and atopic phenotypes in rhinitis trios that were not affected by clinical asthma. IL13 Arg130Gln (rs20541) and G870A (rs1295685) were consistently associated with asthma and serum IgE in both asthma populations. IL4R Glu375Ala (rs1805011) and Ser411Leu (rs1805013) were associated with asthma in the asthma case-control population. Combining risk genotypes of IL13 Arg130Gln with IL4R Glu375Ala, and IL13 C-1111T with IL4R Ser478Pro yielded increased risks for asthma compared to their separate effects. CONCLUSION IL13 polymorphisms were associated with asthma and rhinitis without clinical asthma; thus, these polymorphisms may constitute a common etiologic pathway for their development. In addition, the study replicates a previously reported interaction of IL13 and IL4R polymorphisms in asthma.