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The status of DNA methylation in the human genome changes during the pathogenesis of common diseases and acts as a predictor of life expectancy. Therefore, it is of interest to investigate the methylation level of regulatory regions of genes responsible for general biological processes that are potentially significant for the development of age-associated diseases. Among them there are genes encoding proteins of DNA repair system, which are characterized by pleiotropic effects. Here, results of the targeted methylation analysis of two regions of the human genome (the promoter of the MLH1 gene and the enhancer near the ATM gene) in different tissues of patients with carotid atherosclerosis are present. Analysis of the methylation profiles of studied genes in various tissues of the same individuals demonstrated marked differences between leukocytes and tissues of the vascular wall. Differences in methylation levels between normal and atherosclerotic tissues of the carotid arteries were revealed only for two studied CpG sites (chr11:108089866 and chr11:108090020, GRCh37/hg19 assembly) in the ATM gene. Based on this, we can assume the involvement of ATM in the development of atherosclerosis. "Overload" of the studied regions with transcription factor binding sites (according to ReMapp2022 data) indicate that the tissue-specific nature of methylation of the regulatory regions of the MLH1 and ATM may be associated with expression levels of these genes in a particular tissue. It has been shown that inter-individual differences in the methylation levels of CpG sites are associated with sufficiently distant nucleotide substitutions.

The aim of the study was to identify the features of the genetic structure of myocardial infarction (MI) susceptibility depending on age ("early MI" denoting individuals who had the first MI before the age of 60 years, and "late MI" the group of patients with the first "MI after 60 years"). A total of 355 patients were examined (n = 121 early MI and n = 234 late MI) and 285 residents of the Siberian region (as a control group). Genotyping of 58 single nucleotide variants (SNPs) was performed using mass spectrometry using the Agena (ex Sequenom) MassARRAY® System. Statistical analysis was performed using Statistica 8.0 ("StatSoft Inc.", USA), as well as the "stats" and "genetics" packages in the R environment. The regulatory potential of SNPs was evaluated using the rSNPBase online service (http://rsnp.psych.ac.cn/). eQTL loci were identified using data from the Genotype-Tissue Expression (GTEx) project (http://www.gtexportal.org/) and the Blood eQTL online service (https://genenetwork.nl/bloodeqtlbrowser/). The GG genotype of ITGA4 rs1143674, the CC genotype of CDKN2B-AS1 rs1333049, and the CC genotype of KIAA1462 rs3739998, are generally associated with MI. The AA genotype of ADAMDEC1 rs3765124 (OR = 2.03; 95% CI 1.23-3.33; p = 0.004) and the GG genotype of AQP2 rs2878771 (OR = 2.24; 95% CI 1.23-4.09; p = 0.006) are associated with the development of MI at an early age, and the TT genotype of TAS2R38 rs1726866 (OR = 1.82; 95% CI 1.11-2.89; p = 0.009) was the high-risk genotype for the late MI. Genetic variants associated with MI are regulatory SNP (rSNP) and affect the affinity of DNA binding to transcription factors, carry out post-transcriptional control of gene activity and change the level of gene expression in various tissues. Thus, early and late MI are based on both common genetic variants of ITGA4, CDKN2B-AS1, KIAA1462 genes and specific ones (ADAMDEC1 and AQP2 for early MI and TAS2R38 for late MI).

A group of patients with ischemic heart disease and myocardial infarction (N = 156) and a reference population sample (N = 300) were genotyped for 58 single nucleotide polymorphisms (SNPs) in the genes involved in extracellular matrix function and collagen metabolism or associated with cardiovascular diseases and atherosclerotic plaque stability. Genotyping was performed by mass-spectrometry with two multiplex sets of 27 and 31 SNPs. The study revealed different genetic composition of predisposition to cardiovascular disease continuum (CVDC) syntropy (patients with concomitant conditions: hypercholesterolemia, hypertension, and type-II diabetes mellitus, N = 96) and to isolated myocardial infarction (without these conditions, N = 60). Only the KIAA1462 gene (rs3739998) showed associations with both CVDC syntropy (OR = 1.71; 95% CI 1.19-2.45; р = 0.003) and isolated infarction (OR = 1.58; 95% CI 1.05-2.40; р = 0.028). Isolated myocardial infarction was also associated with LIG1 (rs20579) (OR = 2.08; 95% CI 1.06-4.17; р = 0.028) and ADAMDEC1 (rs3765124) (OR = 1.63; 95% CI 1.07-2.50; р = 0.020). CVDC syntropy was associated with CDKN2BAS1 (rs1333049) (OR = 1.48; 95% CI 1.03-2.12; р = 0.029) and APOA2 (rs5082) (OR = 1.47; 95% CI 1.02-2.11; р = 0.035). So, genes involved in fibrogenesis contribute to predisposition to the myocardial infarction as well. Isolated myocardial infarction and CVDC syntropy can be considered as pathogenetically different cardiovascular conditions, with different genes that contribute to the susceptibility.

We have performed association analysis for mtDNA most common variants and haplogroups with myocardial infarction and some prognostic characteristics in patients. Comparison of patients (N=406) and controls (N=183) has shown higher frequency of HV0 haplogroup in patients (6.9% vs. 2.2%; p=0.033). Patients with early infarction (before age 55), comparing to patiens older than 55 and the first infarction, had higher frequency of 16189C variant (24.1 vs. 12.5%; p=0.008); also, haplogroup U2e was registered only in the subgroup with early infarction (4.4%; p=0.004). On the other side, haplogroup U5 was less frequent in the patients with early infarction (5.1% vs. 15.4%; p=0.002). The patients with recurring cardiovascular incidents during one year follow-up had higher frequency of haplogroup H1 (20% versus 4.5% in the patients without complications, p=0.002) and variant 16189C (30% versus 13.5%; p=0.018). Haplogroup U5 was more frequent in the group of patients with left ventricular ejection fraction less than 40%: 17.1% comparing to 8.2% in the group with ejection fraction>40%; p=0.034. The results suggest that mtDNA polymorphism contributes to coronary atherosclerosis. The associations could be explained by the polymorphism effect on oxidative phosphorylation and reactive oxygen production in mitochondria.

Calcineurin pathway plays the critical role in the cardiac remodeling of various origin, development of chambers dilatation and progression of heart failure. Components of calcineurin pathway are involved in myocardium hypertrophy regulation, angiogenesis and apoptosis. Results of quantitative expression profiling study of main calcineurin pathway genes PPP3CA, PPP3R1, PPP3CB, GATA4 and NFATC4 in myocardium of right atrium auricle of patients with a coronary heart disease, exposed to various types of surgical treatments depending on weight of a clinical finding (surgical reconstruction of the geometry of left ventricle (LV) (postinfarction aneurysm) or coronary artery bypass grafting in case of unaltered morphology of LV) are presented. In patients with sizable postinfarction LV dilatation (n = 21) expression level of calcineurin catalytic subunit genes PPP3CA and PPP3CB was 1.3 and 1.6 times lower (p = 0.018 and 0.023, accordingly) compared to patients with unaltered shape of the heart (n = 34). Expression level of PPP3R1 gene encoding calcineurin regulatory subunit B and GATA4 and NFATC4 genes for transcription factors did not differ in studied subgroups of patients. Thus, lower expression of PPP3CA and PPP3CB genes in atrium myocardium can be related to expressed postinfarction LV remodeling. Further studies of relation quantitative expression profiling of calcineurin pathway genes with the level of damage of myocardium is essential what may have important outcome for the prevention of adverse events of cardiosurgical treatments in patients with postinfarction remodeling.

Association of deletion polymorphism in GSTT1 and GSTM1 genes and polymorphic variant A313G of GSTP1 gene with cirrhosis diseases and 4-year survival rate for the Tomsk region (West Siberia) patients were tested. Homozygous deletion of GSTM1 gene (null genotype) was a protective factor for alcoholic and mixed (HCV, HBV and alcohol) liver cirrhosis development. The patients from the joint group (all etiology forms) as well as having alcoholic and mixed cirrhosis had lower frequency of GSTM1 null genotype (39.2, 39.0, and 34.2%, respectively) in comparison with the control group (64.6%). The GSTM1 null genotype and GSTP1 gene A313G polymorphic variant correlated with the patients' survival rate. The patients survived in comparison with the dead had higher frequency of a GSTM1 null genotype (46.6 vs. 30.2%) and GSTP1 AA genotype (63.1 vs. 40.5%), and lower frequency of GSTP1 AG (A313G) genotype (31.1 vs. 51.2%). A survival rate was 2.5 times higher for patients having GSTP1 AA genotype in comparison with the GG and AG genotype carriers and 2 times higher for patients having GSTM1 null genotype than the gene carriers. A 4-year fatal case probability was 2.3 times higher among the patients having heterozygous AG GSTP1 genotype in comparison with homozygous AA and GG genotype carriers.

Association study was performed for genetic polymorphisms IL4 C(-590)T, IL4RA Ile50Val, TNF G(-308)A, to estimate their effect on quantitative features which are pathogenetically important for chronic viral hepatitis course, i.e. levels of IL4, IL10, IL12, tumor necrosis factor alpha, fibronectin, collagenase, protease inhibitors, macroglobulines, elastases, free and protein-bound hydroxyproline. It has been shown that A allele of TNF G(-308)A polymorphism is associated with decreased TNF-alpha, increased IL4 and IL12, as well as with low level of protein-bound hydroxyproline. In addition, association of CT genotype of IL4 C(-590)T polymorphism and high level of protein-bound hydroxyproline has been identified.

Polymorphic variants of several genes IL4 C(-590)T, IL4RA Ile50Val, TNF G(-308)A were studied for their association with extent of the disease chronization which is marked by hepatic fibrosis stage. Gradual decrease in A allele frequency of polymorphic marker G(-308)A in TNF gene, from patients with weak fibrosis to patients with cirrhosis. Group of patients with weak fibrosis was characterized by higher frequency of A allele (24.5%) comparing with patients with moderate and pronounced fibrosis (13.4%) and cirrhosis (8.7%). Differences in heterozygous genotype frequencies of IL4 C(-590)T were found between patients with cirrhosis (68.2%) and groups of patients with moderate and marked fibrosis (39.1%).

The study was performed to estimate association of the Ile50Val polymorphism in IL4RA and clinical characteristics of chronic viral hepatitis including course of disease manifestation which is determined by degree of hepatic fibrosis. The group under investigation included 61 patient diagnosed with chronic viral hepatitis. Control group consisted of 128 randomly selected inhabitants of Tomsk city. Genotyping of Ile50Val polymorphism in the groups was performed by RFLP (restriction fragment length polymorphism) analysis. There was no significant differences in genotypes and alleles frequencies between cases and controls. However differences in genotype distribution depend on fibrosis stage were detected. Ile/Val heterozygote frequency in subgroup of patients without hepatic fibrosis was lower (7.1%) than in controls (51.6%) (p = 0.002) due to increase of both homozygote classes. Subgroup of patients without hepatic fibrosis differed by genotype frequencies both from patients with moderate and severe disease stage (p = 0.035; p = 0.004).