Identification of Functionally Significant Polymorphic Variants in miRNA Genes in Carotid Atherosclerosis

miRNAs are vital molecules of gene expression. They are involved in the pathogenesis of various common diseases, including atherosclerosis, its risk factors, and its complications. A detailed characterization of the spectrum of functionally significant polymorphisms of miRNA genes in patients with advanced carotid atherosclerosis is an important research task. We analyzed miRNA expression and exome sequencing data of carotid atherosclerotic plaques of male patients (n = 8, 66–71 years of age, 67–90% degree of carotid artery stenosis). For further study and analysis of the association between the rs2910164 polymorphism of the MIR146A gene and advanced carotid atherosclerosis, we recruited 112 patients and 72 relatively healthy Slavic residents of Western Siberia. A total of 321 and 97 single nucleotide variants (SNVs) were detected in the nucleotide sequences of pre- and mature miRNAs in carotid atherosclerotic plaques. These variants were located in 206 and 76 miRNA genes, respectively. Integration of the data of exome sequencing and miRNA expression revealed 24 SNVs of 18 miRNA genes that were processed to mature form in carotid atherosclerotic plaques. SNVs with the greatest potential functional significance for miRNA expression predicted in silico were rs2910164:C>G (MIR146A), rs2682818:A>C (MIR618), rs3746444:A>G (MIR499A), rs776722712:C>T (MIR186), rs199822597:G>A (MIR363). The expression of miR-618 was lower in carotid atherosclerotic plaques of patients with the AC rs2682818 genotype of the MIR618 gene compared with the CC genotype (log2 FC = 4.8; p = 0.012). We also found an association of rs2910164:C (MIR146A) with the risk of advanced carotid atherosclerosis (OR = 2.35; 95% CI: 1.43-3.85; p = 0.001). Integrative analysis of polymorphisms in miRNA genes and miRNA expression is informative for identifying functionally significant polymorphisms in miRNA genes. The rs2682818:A>C (MIR618) is a candidate for regulating miRNA expression in carotid atherosclerotic plaques. The rs2910164:C (MIR146A) is associated with the risk of advanced carotid atherosclerosis.