IL-23R determines susceptibility in Crohn's disease in a Mediterranean area

Association of Interleukin-23 receptor gene polymorphisms with susceptibility to Crohn's disease: A meta-analysis

Studies investigating the association between Interleukin-23 receptor (IL-23R) gene polymorphisms and Crohn’s disease (CD) report conflicting results. Thus, a meta-analysis was carried out to assess the association between the IL-23R polymorphisms and CD. A systematic literature search was conducted to identify all relevant studies. Pooled odds ratio (ORs) with 95% confidence interval (CIs) was used to estimate the strength of association. Finally, a total of 60 case-control studies in 56 articles, involving 22,820 CD patients and 27,401 healthy controls, were included in the meta-analysis. Overall, a significant association was found between all CD and the rs7517847 polymorphism (OR = 0.699, 95% CI = 0.659 ~ 0.741, P < 0.001). Meta-analysis of the rs11209026, rs1343151, rs10489629 and rs11465804 polymorphisms indicated the same pattern as for rs7517847. Meta-analysis showed an association between the rs10889677A allele and CD (OR = 1.393, 95% CI = 1.328 ~ 1.461, P < 0.001). Similarly, meta-analysis of the rs2201840, rs1004819, rs1495965 and rs11209032 polymorphisms revealed the same pattern as that shown by meta-analysis of rs10889677. Stratification by ethnicity revealed that IL-23R gene polymorphisms were associated with CD in the Caucasian group, but not in Asians. In summary, the meta-analysis suggests a significant association between IL-23R polymorphisms and CD, especially in Caucasians.

ATG16L1 and IL23R variants and genetic susceptibility to crohn's disease: mode of inheritance based on meta-analysis of genetic association studies

BACKGROUND

Autophagy and regulation of IL-23 signaling pathways have been implicated in the pathogenesis of Crohn's disease (CD). We studied the mode of inheritance and reviewed the association of 2 polymorphic variants of ATG16L1 and IL23R with CD.

METHODS

We searched the PubMed and ISI Web of Science databases (up to May 2014) for pertinent articles. We included all studies that had a case-control design, with cases having CD and controls being healthy and reported full genotype frequencies for the ATG16L1 and/or IL23R variant of interest. We quantified the relative genetic risk using the model-free approach of the generalized odds ratio metric (ORG) and reported 95% precision estimates. Also, we explored the mode of inheritance using the degree of dominance h-index.

RESULTS

Fifty-one studies fulfilled these requirements and were included in the analysis. These studies involved 12,762 patients and 16,735 controls evaluating the association of ATG16L1 (rs2241880 p.Thr300Ala) and 8110 patients and 11,900 controls evaluating the association of IL23R (rs11209026 p.Arg381Gln) with CD. The ATG16L1 variant rs2241880 was associated with increased susceptibility to CD (combined ORG = 1.38; 95% confidence interval, 1.29-1.48) and a nondominant mode of inheritance (suggesting that the effect of heterozygosity lies exactly in the middle of extreme homozygotes, h = 0). The IL23R variant rs11209026 was associated with significant protection (ORG = 0.46; 95% confidence interval, 0.41-0.53) and a recessive mode of inheritance, indicating that the effect of a heterozygous genotype would lie close to the wild-type homozygous genotype. In subgroup analysis, the significant effects persisted across Caucasian ancestry studies and pediatric populations but were lacking across studies in Asian populations.

CONCLUSIONS

The ATG16L1 variant rs2241880 was associated with 38% increase in the risk for CD for higher mutational load, whereas IL23R variant rs11209026 decreased the risk by 54% for higher mutational load. The mode of inheritance for ATG16L1 variant demonstrated perfect additivity for genetic risk, whereas it showed recessiveness for the IL23R variant. This analysis permits risk stratification for CD based on the mutational status and highlight the need for additional studies in certain populations.

Interleukin-23 receptor genetic polymorphisms and Crohn's disease susceptibility: a meta-analysis

OBJECTIVE

This study was designed to evaluate whether interleukin-23 receptor (IL-23R) polymorphisms were associated with Crohn's disease (CD) susceptibility.

METHODS

PubMed, MEDLINE, and Embase were searched for studies that investigated the IL-23R variants and CD risk. Meta-analysis from all eligible case-control studies was performed to assess the purported associations.

RESULTS

Our analysis found that variant minor alleles for single nucleotide polymorphisms (SNPs) rs11209026 (Arg381Gln) (P < 0.00001, OR = 0.43, 95% CI (0.37-0.50)) and rs7517847 (G/G vs. T/T, P < 0.00001, OR = 0.49, 95% CI (0.38-0.64); G/G vs. T/G + T/T, (P < 0.00001, OR = 0.56, 95% CI (0.44-0.72); T/G + G/G vs. T/T, (P < 0.00001, OR = 0.71, 95% CI (0.64-0.79) of IL-23R were inversely associated with CD risk; sensitivity analysis also indicated that Caucasian population with a variant of Arg381Gln has a decreased risk for developing CD (P < 0.00001, OR = 0.43, 95% CI (0.36-0.50)).

CONCLUSION

Our meta-analysis supports that two polymorphisms (Arg381Gln and rs7517847) within the IL-23R gene may be considered to be protective factors against developing CD. Further large case-control studies especially concerning ethnicity differences and genotype-phenotype interaction should be performed to clarify possible roles of IL-23R in CD.