Association of Single Nucleotide Polymorphisms of IL23R and IL17 with Ulcerative Colitis Risk in a Chinese Han Population

BACKGROUND: Previous studies implicated that IL23R and IL17 genes play an important role in autoimmune inflammation. Genome-wide association studies have also identified multiple single nucleotide polymorphisms (SNPs) in the IL23R gene region associated with inflammatory bowel diseases. This study examined the association of IL23R and IL17A gene SNPs with ulcerative colitis susceptibility in a population in China. METHODOLOGY: A total of 270 ulcerative colitis and 268 healthy controls were recruited for the analyses of 23 SNPs in the IL23R and IL17A regions. Genomic DNA was extracted and analysis of these 23 SNPs using ligase detection reaction allelic (LDR) technology. Genotype and allele associations were calculated using SPSS 13.0 software package. PRINCIPAL FINDINGS: Compared to the healthy controls, the variant alleles IL23R rs7530511, and rs11805303 showed a statistically significant difference for ulcerative colitis susceptibility (0.7% vs 3.3%, P = 0.002; 60.4% vs 53.2%, P = 0.0017, respectively). The linkage disequilibrium (LD) patterns of these SNPs were measured and three LD blocks from the SNPs of IL23R and one block from those of IL17A were identified. A novel association with ulcerative colitis susceptibility occurred in haplotypes of IL23R (Block1 H3 P = 0.02; Block2 H2 P = 0.019; Block3 H4 P = 0.029) and IL17A (H4 P = 0.034). Pair-wise analyses showed an interaction between the risk haplotypes in IL23R and IL17A (P = 0.014). CONCLUSIONS: Our study demonstrated that rs7530511, and rs11805303 of IL23R were significantly associated with ulcerative colitis susceptibility in the Chinese population. The most noticeable finding was the linkage of IL23R and IL17A gene region to ulcerative colitis risk due to the gene-gene interaction.