The IL1A genotype is associated with nasal polyposis in asthmatic adults

Background: Nasal polyposis (NP) is a chronic inflammatory disease often found coexisting with asthma. As this disorder tends to cluster in families, a genetic predisposition has been suggested. Interleukin-1 (IL-1) has been proposed to play a role in the pathogenesis of NP. Methods: We analysed the single G-to-T base exchange polymorphism in exon 5 at +4845 of the gene encoding IL-1alpha (IL1A ) and the C-to-T base exchange polymorphism at -511 of the gene encoding IL-1beta (IL1B ) in a population-based sample of adult asthma patients (n = 245). The data were assessed for correlation with data on history of NP and other phenotype-related characteristics. Results: The prevalence of NP in our study group was 14.3%. The distribution of the IL1A genotype differed significantly between asthmatics with and without NP (P = 0.005). The risk of NP was markedly increased in allele G homozygous subjects (OR = 2.73; 95%CI = 1.40-5.32). In the case of IL1B we found no significant associations. Asthmatics with NP had more symptoms than others, but lung function and blood eosinophil counts were similar. Conclusions: Our study demonstrates an association of IL1A with NP inasthmatic patients and addresses the role of IL-1alpha as an inflammatory modulator in the pathogenesis of this disease.