The Role of Interleukin-4 and 13 Gene Polymorphisms in Allergic Rhinitis: A Case Control Study

Background: Allergic Rhinitis (AR) is an IgE-mediated inflammatory disorder with high morbidity rates. The eitiology of this disease is understood to occur from a complex interaction between genetic and environmental factors. T helper type 2 cells have been shown to have a crucial role in atopic disease due to their production of the cytokines, intelukin and , involved in inflammation. Research has shown single nucleotide polymorphisms (SNP) of the and genes to be associated increased levels of IgE and with allergic diseases such as, allergic rhinitis, asthma, and atopic dermatitis. Specifically, the rs2243250 SNP of IL-4 and the rs20541 SNP of have been shown to be associated with AR.

Methods: A case-control study was designed to investigate the relationship between the two SNPs rs2243250 and rs20541 with the incidence of AR. The SNPs were examined in patients with AR and healthy controls (86 patients and 86 controls). Blood samples were collected and DNA was extracted to evaluate the SNPs by RFLP-PCR.

Results: Recessive analysis model of the gene (GG vs. AA+AG) revealed that the GG genotype was more common in AR patients (P=0.36) )OR=0.8 [81% CI 0.38-1.6]). For the gene (TC vs. TT+CC), the TC genotype was more common in AR patients (P = 0.0022)) OR=0.71 [60% CI 1.41-5.02]). Furthermore, in the IL-4 gene, the 590 T>C polymorphism had a significant association with AR. However, no association was found between AR and the rs20541 polymorphism.

Conclusion: Our findings suggest that the polymorphism (rs20541, Exo 4, G>A, Arg130Gln) and IL-4 polymorphism (rs2243250= C-590T, promoter, T>C) are co-associated with AR and sensitivity to aeroallergens. However, this study used a cohort of AR patients and healthy controls from the northeast of Iran. Given the influence of ethnicity and environment on genetics, further investigation is needed to elucidate the role of SNPs in and in AR among different populations.