Polymorphisms in the IL2RA and IL2RB genes in inflammatory bowel disease risk.

Associations with different autoimmune diseases of polymorphisms in genes encoding the IL2RA and IL2RB subunits (located in 10p15 and 22q13, respectively), were identified through genome-wide studies. Polymorphisms in these two genes were studied in 107 inflammatory bowel disease (IBD) patients (39 Crohn's disease [CD] and 68 ulcerative colitis [UC]) and in 162 ethnically healthy controls from Tunisia (Sfax). Two of the 15 IL2RA single-nucleotide polymorphisms (SNPs) genotyped (rs4749924 and rs706778) were significantly associated with UC (pcorr=0.018 and 0.048, respectively), but no evidence of association with CD was observed. The IL2RA GTCT haplotype was also more frequent in UC patients compared to controls (2.6% vs. 0%; p=0.002). One of the 6 IL2RB SNPs genotyped (rs743776) was significantly associated with CD (pcorr= 0.039), but no evidence of association with UC was observed. No significant association between IL2RB haplotypes was observed among investigated groups. Our study identified markers in the IL2RA and IL2RB genes that are significantly associated with UC and CD, respectively. Our results supporting IL2RA and IL2RB as promising candidate genes for IBD and suggesting a potential role of IL2R in the pathogenesis of IBD, likely involves regulatory T cells.