Replication of an Association Between IL23R Gene Polymorphism With Inflammatory Bowel Disease

Abstract

Background & Aims: Recently, the interleukin 23 receptor (IL23R) gene encoding a subunit of the receptor of the inflammatory cytokine IL-23 has been identified as a novel genetic factor strongly associated with inflammatory bowel disease (IBD). We aimed to replicate the IBD association of IL23R genetic markers in an IBD independent Spanish cohort. Methods: Four hundred sixty IBD patients of Spanish white origin (238 CD and 222 UC) and 342 ethnically matched healthy controls comprised the study population. Eight single nucleotide polymorphisms (SNPs) spanning the IL23R gene and its downstream intergenic region were selected as genetic markers and genotyped by using Taqman 5′ allelic discrimination assay. Results: All genetic variants located within the IL23R gene were observed to confer a strong protective effect against IBD susceptibility in our population. The Arg381Gln (rs11209026) non-synonymous SNP was most significantly associated with IBD protection (odds ratio, 0.4; 95% confidence interval, 0.3-0.7). In addition to the single SNP analysis, we performed a haplotype analysis identifying 2 haplotypes significantly associated with IBD protection. Conclusions: In this study we replicate the association of IL23R genetic variants with IBD in a Spanish population. These findings, together with the previous results, suggest that the IL23R gene is one of the genetic factors implicated in the genetics of IBD in the general population. © 2007 AGA Institute.