Association between microRNA polymorphisms and the risk of inflammatory bowel disease.

Common single nucleotide polymorphisms (SNPs) in precursor microRNAs may change their properties via altering the expression of miRNAs, resulting in diverse functional consequences. The present study evaluated the effects of four common SNPs in pro-miRNAs on the risk of inflammatory bowel disease (IBD) and IBD‑associated colorectal cancer (IBD-CRC). In a hospital based case‑control investigation in a Chinese population, 468 patients with IBD and 450 age- and gender-matched healthy subjects were enrolled in the present study. The SNPs were genotyped using a polymerase chain reaction (PCR)-restriction fragment length polymorphism technique. The expression levels of the miRNAs were detected by reverse transcription‑PCR. For rs2910164, the risk of IBD was significantly increased in the GC and CC genotypes. The mean expression levels of mir‑146a in the CC and GC genotypes were lower, compared with that of the GG genotype. For rs2292832, an increased risk of IBD was detected in the recessive model of the TT genotype, compared with the combination of the CT and CC genotypes. The [T] allele was found to be at increased significantly, with a 1.268‑fold increased risk of IBD, compared with the [C] allele. The mean expression levele of mir‑149 expression level in the TT genotype was lower, compared with that of the CC genotype. For rs11614913, the risk of IBD‑CRC was significantly increased in the CC genotype, compared with the TT genotype. In the dominant model, the CC genotype had a high risk of IBD‑CRC, compared with the combination of the CT and TT genotypes. These findings suggested that mir-146a rs2910164 and mir‑149 rs2292832 may be associated with the increased risk of IBD via alterations in the expression levels of miRNAs. Therefore, mir‑196a rs11614913 may contribute to the progression of IBD-CRC.