In addition to the IL2/IL21 locus, we observed association of the TT genotype of SNP rs1545620 in MYO9B with UC (P = 0.0169; OR = 0.29, 95% CI 0.11-0.78) and association of rs17375018 in IL23R with pancolitis in Chinese UC patients (P = 0.002; OR = 2.38, 95% CI 1.41-4.02).
The data show an association of both IL23R SNPs with overall IBD (statistically stronger, rs7517847; odds ratio [OR] = 0.79, 95% confidence interval [CI]: 0.67-0.94, minor allele frequencies: 0.355 in IBD patients versus 0.410 in controls; P = 0.005), somewhat stronger in Crohn's disease (OR = 0.74, 95% CI: 0.61-0.91) than in ulcerative colitis (OR = 0.84, 95% CI: 0.69-1.03).
Th17 T<sub>EM</sub> cells (expressing <i>IL17A, IL17F, RORC</i>, and <i>STAT3</i>) displayed a higher pathogenic/cytotoxic (<i>IL23R, IL18RAP</i>, and <i>GZMB, CD160, PRF1</i>) gene signature in CD relative to UC, while non-pathogenic/regulatory genes (<i>IL9, FOXP3, CTLA4</i>) were more elevated in UC.
IL23R was associated with CD and UC only in the absence of CARD15 mutations, whereas ATG16L1 was associated with CD in the presence and absence of CARD15 mutations.
We were able to replicate the association of the IL23R variants with CD as well as HLA-DRB1*0103 with UC; confirmation of TNFRSF1A association with UC needs additional studies.
The polymorphisms TLR2 (rs1816702), NFKB1 (rs28362491), TNFRSF1A (rs4149570), IL6R (rs4537545), IL23R (rs11209026) and PTPN22 (rs2476601) were associated with risk of CD and the polymorphisms TLR2 (rs1816702), TLR4 (rs1554973 and rs12377632), TLR9 (rs352139), LY96 (rs11465996), NFKBIA (rs696), TNFA (rs1800629), TNFRSF1A (rs4149570), IL10 (rs3024505), IL23R (rs11209026), PTPN22 (rs2476601) and PPARG (rs1801282) were associated with risk of UC.
Novel genetic risk markers for ulcerative colitis in the IL2/IL21 region are in epistasis with IL23R and suggest a common genetic background for ulcerative colitis and celiac disease.
One hundred and eighty unrelated IBD patients [57 Crohn's disease (CD) and 123 ulcerative colitis (UC)] and 186 healthy controls were genotyped for the following known genetic susceptibility variants: NOD2 - Arg702Trp (rs2066844), rs2066845" genes_norm="64127">Gly908Arg (rs2066845) and Leu1007insC (rs2066847), as well as IL23R - rs11209026;rs901312933" genes_norm="149233;55054">Arg381Gln (rs11209026) and ATG16L1 - rs2241880;s2241880;rs1384936174" genes_norm="55054;64127">Thr300Ala (rs2241880).
Given the association of IL23R with inflammatory bowel disease (IBD), we characterized the role of IL-17F in IBD including its intestinal gene expression and the effect of the IL17F p.His161Arg polymorphism on disease susceptibility and phenotype of Crohn's disease (CD) and ulcerative colitis (UC).
Genome-wide association studies (GWAS) in several populations have demonstrated significant association of the IL23R gene with IBD (Crohn's disease (CD) and ulcerative colitis (UC)) and psoriasis, suggesting that perturbation of the IL-23 signaling pathway is relevant to the pathophysiology of these diseases.
The aims of the study were to replicate the association with CD, examine subphenotype associations and statistical interactions with CARD15, IL23R, and the IBD5 risk haplotype, as well as explore the association with UC.
Eight single nucleotide polymorphism markers in IL23R tested in the North American study were genotyped in 1902 cases of Crohn's disease (CD), 975 cases of ulcerative colitis (UC), and 1345 controls using MassARRAY.
IL23R is an IBD susceptibility gene, but has no epistatic interaction with CARD15 and SLC22A4/5. rs1004819 is the major IL23R variant associated with CD in the German population, while the p.Arg381GlnIL23R variant is a protective marker for CD and UC.