The IL-22 levels in carriers of CD risk-increasing IL23R variants were significantly higher than in carriers of CD risk-decreasing IL23R variants (P = 0.008).
These observations suggest that IL23R makes a substantial contribution to CD susceptibility, larger than that estimated from the population frequency of the R381Q variant.
The aims of this study were to replicate the association of IL23R with Crohn's disease (CD), examine subphenotype relationships, and look for evidence of epistasis with the known CD susceptibility gene CARD15 and susceptibility haplotype IBD5 in a large collection of CD patients.
A total of 438 individuals (143 with pediatric-onset CD [age <18 years], 139 with adult-onset CD, and 157 control subjects) evaluated for age at onset and disease location were genotyped for the R381Q mutation in the IL-23 receptor gene by pyrosequencing.
We replicated the previously reported associations between CD and rs11209026 and rs2241880, confirming that IL23R and ATG16L1 are susceptibility loci for CD in the New Zealand population.