Haplotype-based analysis of ulcerative colitis risk loci identifies bothIL2andIL21as susceptibility genes in Han Chinese

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Abstract

Background:

The incidence of ulcerative colitis (UC) varies between Western and Eastern ethnicities. A distinct genetic background may play a role in the differences. Until now, very little was known of the UC genetics in Asian populations. Here we performed a haplotype-based analysis of six known UC susceptibility loci in Han Chinese patients.

Methods:

In all, 245 UC patients and 300 healthy controls of Han Chinese descent were genotyped for 27 single nucleotide polymorphisms (SNPs), which cover the major haplotypes of the chromosome regions containing IL10, IL2/IL21, MYO9B, ECM1, MST1, and IL23R in Han Chinese.

Results:

In contrast to the tight linkage disequilibrium (LD) block of the IL2/IL21 region in Caucasians, IL2 and IL21 reside in two independent LD blocks in Han Chinese. The IL2 SNP rs2069762 (P = 7.0 × 10−4, odds ratio [OR] = 1.54, 95% confidence interval [CI] 1.20–1.99) and the IL21 SNP rs2055979 (P = 1.2 × 10−4, OR = 1.50, 95% CI 1.17–1.92) were independently associated with UC. We identified one risk haplotype in IL2 and another independent risk haplotype in IL21. 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).

Conclusions:

Our study confirmed the association of the IL2/IL21 region with UC in Han Chinese patients, and further implied both IL2 and IL21 as genetic risk factors for UC. Han Chinese UC patients share part of their genetic susceptibility with Caucasian patients.

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