ABSTRACT. Colorectal cancer (CRC) is a multi-factorial disease, and genetic background may contribute to its etiology. Single nucleotide polymorphisms (SNPs) in microRNAs (miRNAs) may be used as specific markers of predisposition for CRC diagnosis and prevention. In this review, we summarize and discuss recent publications evaluating the roles of miRNA SNPs in CRC. A meta-analysis was also carried out to assess the association between the five most frequently studied miRNA SNPs and CRC risk. No relationship was established between this disease and the three SNPs rs11614913, rs2910164, and rs3746444 in miR-196a-2, miR-146a, and miR-499, respectively. However, polymorphisms of miR-149 (rs2292832; CT vs TT: odds ratio [OR] = 0.816, 95% confidence interval [CI] = 0.691-0.963; CC+CT vs TT: OR = 0.834, 95%CI = 0.715-0.972) and pre-miR-27a (rs895819; GG vs AA: OR = 1.534, 95%CI = 1.148-2.049; GG+AG vs AA: OR = 1.324, 95%CI = 1.066-1.645) were found to be associated with CRC in our analysis. In conclusion, the SNPs rs2292832 in miR-149 and rs895819 in pre-miR-27a were associated with CRC susceptibility, whereas rs11614913, rs2910164, and rs3746444 in miR-196a-2, miR-146a, and miR-499, respectively, were not. Further studies should be carried out to validate these findings.

ABSTRACT. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules of about 22 nucleotides in length. miRNAs are highly conserved in both plants and animals, and function as gene regulators by binding to the 3'-untranslated region of target mRNAs for cleavage and/ or translational repression. miRNA biogenesis, stability, and regulation of expression are strongly sequence dependent. Sequence variants, such as single nucleotide polymorphisms (SNPs) in pri-miRNA, pre-miRNA, promoter regions, or miRNA-target sites, can influence miRNA function, thereby contributing to the pathological features of human disease. In this review, we focus on miRNA-related SNPs in gastric cancer and comprehensively analyze some commonly studied SNPs.