[Association of Polymorphic Genome Variants in the 2q32.1 Locus with the Development of Vasovagal Syncope].

The vasovagal syncope (VVS) is the most common form of syncope. The mechanisms of VVS development are not entirely clear. It is known that there is a genetic predisposition to this disease, but the data on the roles of individual genes are quite contradictory. Recently, a genome-wide association study identified a locus at chromosome 2q32.1 associated with a united group of diseases, that is, syncope and collapse; among the single nucleotide polymorphisms (SNPs) of this locus, the most significant association was observed for rs12465214. In a homogeneous sample of patients diagnosed with VVS, we analyzed the association of rs12465214, rs12621296, rs17582219 and rs1344706 located on chromosome 2q32.1 with this form of syncope. In the enrolled set, only rs12621296 was associated with VVS by itself, whereas associations of other SNPs were observed only in biallelic combinations. An epistatic interaction between the components of the combination rs12621296*A + rs17582219*A was revealed. The possible involvement of individual genes on the 2q32.1 locus in the genetic architecture of the VVS is discussed.

[MiRNA miR-375 as a Multifunctional Regulator of the Cardiovascular System].

MicroRNA (miRNA) miR-375 acts as a multifunctional regulator of the activity of many physiological and pathological cellular processes by interacting with a large number of target genes. MiR-375 is involved in the regulation of the differentiation and functioning of cells of the nervous and immune systems, bone and adipose tissue, and even the life cycle of a number of viruses. Changes in miR-375 expression have been found in carcinogenesis, inflammation, and autoimmune and cardiovascular diseases. Every year, new studies appear that expand our understanding of the range of processes regulated by this miRNA. According to the latest data, miR-375 can be used as a biomarker and therapeutic target in some diseases. This review discusses the role of miR-375 in the functioning of the cardiovascular system in health and disease.

[The Myocardial Infarction Associated Variant in the MIR196A2 Gene and Presumable Signaling Pathways to Involve miR-196a2 in the Pathological Phenotype].

The heritable component of susceptibility to myocardial infraction (MI) remains unexplained, possibly due to the minor effects of genes, which are not obviously associated with the disease. These genes may be integrated in miRNA regulated networks associated with myocardial infarction. A systematic review of the literature led us to selecting rs2910164 (MIR146A), rs11614913 (MIR196A2), and rs3746444 (MIR499А) variants to study the association with the MI phenotype. In ethnic Russians, variant rs11614913*C (MIR196A2) was found to be associated with the risk of myocardial infraction (p = 0.023, OR = 1.74) for the first time; this association was validated in an independent cohort. The gene-gene interaction network for experimentally validated miR-196a2 target genes was built and analyzed. One of its four topological clusters contained the majority of miR-196a2 target genes associated with atherosclerosis, coronary artery disease or myocardial infarction and was enriched with the genes regulating the TGFß and class I MHC signaling pathways, platelet activation/aggregation, and the cell cycle control. This analysis points towards the role of miR-196a2 in the pathological coronary phenotypes and opens up an avenue for further investigations.

Multilocus Analysis of Genetic Susceptibility to Myocardial Infarction in Russians: Replication Study.

In search of genetic markers of myocardial infarction (MI) risk, which have prognostic significance for Russians, we performed a replication study of MI association with genetic variants of PCSK9 (rs562556), APOE (epsilon polymorphism, rs7412 and rs429358), LPL (rs320), MTHFR (rs1801133), eNOS (rs2070744), and the 9p21 region (rs1333049) in 405 patients with MI and 198 controls. Significant MI association was observed with variants of the lipid metabolism genes (PCSK9, APOE and LPL), and of eNOS. The SNPs in the MTHFR gene and the 9p21 region were not significantly associated with MI one by one but were included in several different MI-associated allelic combinations identified by multilocus analysis. Since we have not revealed nonlinear epistatic interactions between the components of the identified combinations, we postulate that the cumulative effect of genes that form a combination arises from the summation of their small independent contributions. The prognostic significance of the additive composite model built from the PCSK9, APOE, LPL, and eNOS genes as genetic markers was assessed using ROC analysis. After we included these markers in the previously published composite model of individual genetic risk of MI, the prognostic efficacy in our sample reached AUC = 0.676. However, the results obtained in this study certainly need to be replicated in an independent sample of Russians.

[Multilocus analysis of the association of polymorphic variants of inflammation genes with ischemic stroke in Russians].

Carriage frequencies of alleles and genotypes of polymorphic loci of inflammation genes (49A>G CTLA4, 41G>A and 87C>T PDE4D, -590C>T IL4, -308A>G TNF, 252G>A LTA, 874A>T IFNG, -509С>Т, 869T>C and 915G>C TGFB1) were determined in a sample of 200 patients diagnosed with ischemic stroke and in the control group similar in gender and age (146 individuals), all ethnic Russians. The positive association of the allele PDE4D*87C (р = 0.028) and genotype TGFB1*-509Т/Т (р = 0.02) carriage with ischemic stroke was shown. The association of the disease with the carriage of the allele PDE4D*41А (р = 0.009) in individuals under the age of 60 and with carriage of the allele IFNG*874Т (р = 0.02) in individuals older than 60 was observed among the subgroups of patients stratified by age when they suffered the stroke compared to a control group of the same age. In subgroups stratified by gender, carriage of the genotype TGFB1*915G/G (р = 0.0015) was identified as a risk factor in male patients, while no significant differences between female patients and healthy women were observed. Multilocus analysis was undertaken to search for the association of several combinations of studied gene variants with ischemic stroke. The polymorphic locus-174G>C of the IL6 gene, for which an association with the disease was previously demonstrated, was also included in this analysis. The disease-predisposing biallelic combinations include the IL6*-174G, PDE4D*87C, TGFB1*-509Т and TGFB1*915G alleles. In the subgroups stratified by gender, the allelic combinations mainly include the similar risk alleles as in the total group, while between the subgroups stratified by age (patients who suffered the first stroke at the age of 18 and no older than 60 years and older than 60 years), greater differences were observed. However, a new risk allele, LTA*252G, was identified in combination with PDE4D*41А in women. These findings demonstrate the important role of inflammation in ischemic stroke. The identified single and combined markers may be used further to determine an individual risk for ischemic stroke.

[Combined Effect of Genetic Factors, Age, and Smoking on the Risk of Developing Myocardial Infarction].

OBJECTIVE: to elaborate a complex model for myocardial infarction (MI) risk assessment considering the combined effect of genetic predisposition, age and smoking. MATERIALS AND METHODS: The study included two independent samples of ethnic Russians: 325 patients with MI and 185 individuals without history of cardiovascular diseases (controls) from the Moscow region, and 220 patients and 197 controls from the Republic of Bashkortostan. Genotyping of polymorphic loci of genes CRP (rs1130864), IFNG (rs2430561), TGFB1 (rs1982073), FGB (rs1800788) and PTGS1 (rs3842787) was performed. To construct the predictive models, we used logistic regression with stepwise inclusion of variables. The predictive value was evaluated by the area under the curve (AUC) in a ROC-analysis. The factor was considered as a marker at pAUC <0.05 calculated by the method of DeLong. The marker was considered effective at AUC >0.60. RESULTS: Three separate genetic variants FGB rs1800788*T, TGFB1 rs1982073*TT, CRP rs1130864*TT, and biallelic combination IFNG rs2430561*A + PTGS1 rs3842787*T whose association with MI we described earlier, were used to construct the composite genetic marker (AUC=0.66 in the training and test samples) by the logistic regression method. Adding to the obtained composite genetic marker such parameters as age and smoking allowed to create a complex MI risk marker, which was characterized by the predictive value stability (AUC=0.77 in the training sample and 0.82 in the test sample). CONCLUSION: The obtained complex model for MI risk assessment was reproduced in two independent samples of Russian ethnicity individuals from different regions of Russia with different gender identities, and allowed to have a reasonable chance (about 80%) of distinguishing patients and healthy individuals.

[Ischemic stroke as a complex polygenic disease].

In the modern world acute cerebrovascular accidents (strokes) are one of the most important sociomedical problems due to their high share in the structure of morbidity, invalidization and mortality of the population. The main part of strokes is ischemic stroke (IS). IS is a complex (multifactorial) polygenic disease, i.e. develops as a result of interactions between risk factors and genetic components that determine a joint contribution of the sets of independently acting or interacting polymorphic genes. Currently, the search for a genetic predisposition to IS uses two main methods that are based on the analysis of the association between the polymorphic regions of the genome and disease: a candidate gene approach and genome-wide association studies, followed by a meta-analysis of the received results. In this work we reviewed the literature on genetic susceptibility to IS. It showed progress in this direction, which can be the starting point for the study of the molecular mechanisms determining the pathophysiology of IS. However to a full solution of the problem of identification of the genetic risk factors applicable for the individual prognosis of predisposition to IS, still very far, mainly due to the low replication of results. The way to solve this problem lies through the study of ethnically homogeneous populations and clinically different forms of IS.

Contribution of the TGFB1 Gene to Myocardial Infarction Susceptibility.

Carriage frequencies of alleles and genotypes of theTGFB1 gene polymorphous loci -509C>T (rs1800469), 869T>C (rs1982073), 915G>C (rs1800471), which affect the level of cytokine TGF-ß1 production, were analyzed in the patients of Russian ethnic descent with myocardial infarction (MI) (406 cases) and in the control group of the same ethnic descent (198 controls). Significant association with MI was observed in carriage frequencies of the alleleTGFB1*-509T (p=0.046, OR =1.45, 95% CI: 1.02-2.06), genotypes TGFB1*869T/T (p=0.0024, OR =1.75, 95% CI: 1.22-2.51), andTGFB1*915G/G (p=0.048, OR=1.76, 95% CI: 1.05-2.97). Linkage disequilibrium analysis for these SNPs has shown that the associations revealed can be considered to be independent. A complex analysis of MI association with combinations of alleles/genotypes of said SNPs indicates their cumulative effect. An analysis of susceptibility to early-onset MI (≤ 50 years old) revealed a positive association of the alleleTGFB1*-509T (p=0.002, OR=2.24, 95% CI: 1.35-3.71) and genotypeTGFB1*869T/T (p=0.008, OR=1.93, 95% CI: 1.18-3.15), as well as their additivity. An analysis of susceptibility to recurrent MI revealed an association of the genotypeTGFB1*-509T/T (p=0.0078, OR=2.60, 95% CI: 1.28-5.28). The results obtained indicate the important role of theTGFB1gene in susceptibility to MI, including early-onset and recurrent MI, in Russians.

[Value of allele gene polymorphism of the inflammation system for prognosis of patients with myocardial infarction].

In recent years levels of a number of inflammatory markers namely C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor (TNF) etc. are measured for the purpose of postinfarction risk evaluation. Dynamics of inflammatory markers concentrations can reflect processes occurring in atherosclerotic plaque and coronary arteries. Concentrations of inflammatory markers depend particularly on genetic factors affecting transcription levels of individual genes. This data suggest that genotypes which determine increased inflammatory markers levels in blood can increase risk of unfavorable events after myocardial infarction. STUDY PURPOSES: Analysis of influence of allelic polymorphisms C1444T of CRP gene (rs1130864), G(-174)A of IL6 gene (rs1800795), A(-308)G of TNF gene (rs1800629), G252A of LTA gene (rs909253), (-509) of TGFB1 gene (rsl800469) and delta32 (w/d) of CCR5 gene (rs333) on development of cardiac unfavorable events in Russian patients with MI during two years follow-up. 211 Russian patients were included (52.3+/-10.3 years), 160 men (50.1+/-10.6 years) and 51 women (55.2+/-10.1 years). After two years of follow-up patients were examined in hospital, or telephon call occurred for determination of patient's condition or end point assessment. The end points were cardiac death, recurrent MI, recurrent hospitalization with unstable angina or stroke, CABG or PTCA performing. The genotyping was performed by methods based on polymerase chain reaction (PCR): PCR-SSP and PCR-RFLP. Analysis revealed association of allele T (p=0.036, OR=1.6, 95%CI: 1.052.6) and of allele T carriage (genotypes CT+TT) (p=0.046, OR=1.9, 95%CI: 1.053.6) of polymorphism C1444T of CRP gene with unfavorable events development. Analysis of survival rate by Kaplan-Meier estimation showed that cumulative part of patients without unfavorable events was significantly lower among allele T carriers than among carriers of genotype C/C of polymorphism C1444T CRP. Allele A of polymorphism A252G of LTA gene was also associated with unfavorable events risk (p=0.034, OR=1.96, 95%CI: 1.073.06). There was no association of polymorphisms delta 32 (w/d) of CCR5 gene, A(-308)G of TNF gene, G(-174)C of IL-6 gene, C(-509)T of TGFB1 gene with unfavorable events development.

[Polymorphic variants of genes encoding interleukin-6 and fibrinogen, the risk of ischemic stroke and fibrinogen levels].

Carriage frequencies of alleles and genotypes of polymorphous locus of -174G>C IL6 (rs1800795) were analyzed in the patients with ischemic stroke (IS) of Russian ethnic descent (200 cases) and in the control group of the same ethnic descent with similar sex and age (140 controls). Significant differences were identified in frequencies of carriage (in homo- or heterozygous form) of allele IL6*-174G (p = 0.0029, OR = 2.9, 95% CI: 1.4-5.8), which can be considered as risk factor for IS and in frequencies of IL6*-174C/C genotype carriage, correspondingly (p = 0.0029, OR = 0.35, 95% CI: 0.17-0.69). After sex stratification of patients and controls similar significant differences were observed only between female patients and controls, after age stratification the difference was observed only for the age group older 60 years. Complex analysis of association of SNP -174G>C IL6 alleles and genotypes carriage in combination with SNP 4266A>G (Thr312Ala) FGA (rs6050) (see symbol) -249C>T FGB (rs1800788) with IS revealed protective combinations IL6*-174C/C + FGA* 4266A (see symbol) IL6*-174C/C + FGB*-249C, which were slightly more significant than single protective genotype IL6*-174C/C associated with IS and their ORs didn't differ substantially from the single genotypes's OR value. At the same time the combinations of alternative allele IL6*-174G with the same FGB*-249C or FGA* 4266A alleles were revealed and their association significance levels as well as OR values were lower than the values for the single risk allele IL6*-174G. In case of the mutual carriage of IL6*-174G allele with FGA*4266A/A, FGB*-249C/C genotypes or with combinations of these alleles/genotypes the "neutralized" effect became stronger. In other words, we observed association of IS with allele/genotype combinations of genes IL6, FGA and FGB, in which IL6 plays key role and FGA and FGB have modulating function. In analysis of association of fibrinogen plasma levels with three analyzed polymorphous loci significant differences were not revealed.

Family Analysis of Linkage and Association of HLA-DRB1, CTLA4, TGFB1, IL4, CCR5, RANTES, MMP9 and TIMP1 Gene Polymorphisms with Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS). Proteins of the immune system, as well as proteins that are involved in the infiltration of activated immune cells in the CNS, play an important role in the pathogenesis of MS. We investigated the association and linkage with MS of the following immune-system genes polymorphisms: HLA-DRB1,CTLA4,TGFB1,IL4,CCR5 andRANTES, as well as of the matrix metalloproteinase 9 (MMP9) and tissue inhibitor of metalloproteinase  1 (TIMP1) genes polymorphisms. For this purpose we used the transmission disequilibrium test (TDT). The group investigated was comprised of 100 nuclear families of Russian ethnicity, each consisting of an affected offspring and his nonaffected parents. It was found that HLA-DRB1*15alleleandMMP9*-1562C allele were transmitted from healthy heterozygous parents to affected children more frequently than alternative alleles (p  =  0.02 andp  =  0.04, respectively). Another family-based method, AFBAC (affected family-based control), showed MS association with HLA-DRB1*15, but not with theMMP9*-1562C allele.

[Complex analsis of association of inflammation genes with myocardial infarction].

Carriage frequencies of alleles and genotypes of functionally important polymorphous loci of some inflammation genes: proinflammatory cytokines genes IL-6, LTA and TNF, anti-inflammatory cytokine gene TGFB1 and CC chemokine receptor 5 gene CCR5 were analyzed in the patients with myocardial infarction (MI) of Russian ethnic descent (199 cases) and in the control group of the same ethnic descent (142 controls). Complex analysis using APSampler algorithm revealed MI association with carriage of all polymorphous variants studied, as individual risk factors (insertion/deletion polymorphism of CCR5 and SNP G252A LTA) or only in combination with other alleles/genotypes. Carriage of bi- or triallelic combinations was associated with MI more significantly than carriage of any their subsets: single alleles or allele pairs. Protective triallelic combination d*CCR5 + 252G*LTA(+) -174C*Ll-6 was found to be most significant (p = 0.0006, OR = 0.23, CI = 0.090-0.56). Separate analysis of genetic susceptibility to MI for men and women displayed sexual dimorphism for CCR5 gene.

[Complex analysis of genetic predisposition to ischemic stroke in Russians].

Carriage frequencies of alleles and genotypes of 10 functionally important single nucleotide polymorphisms that are located in genes FGA, FGB, APOE, LPL, ACE and CMA1 were analyzed in the ischemic stroke (IS) patients of Russian ethnic descent and in the control group of the same ethnic descent and of similar gender and age. Comparison between patients and control group revealed no significant differences in frequencies of individual alleles and genotypes for all the polymorphic loci studied. However, complex analysis of genetic predisposition using APSampler algorithm revealed carriage of allele (-491A) APOE as a predisposing factor for IS (p = 0.044, OR 3.8, 95% CI 1.0-15.1). Accordingly, carriage of genotype (-491T/T) APOE was associated with resistance to IS (p = 0.044, OR 0.26, 95% CI 0.07-1.0). The allele -249C FGB carriage addition to this genotype enhances its protective properties, p-value of the combination is 2-fold lower than that of the genotype (-491T/T) APOE (OR 0.17, 95% CI 0.04-0.8). Two more protective combinations were identified: biallelic (-427C) APOE + (1595G) LPL and triallelic (-491C) APOE + (1595G) LPL + (-1903G) CMAI (in both cases p = 0.0052, OR 0.18, 95% CI 0.05-0.66). Overall, involvement in formation of the risk of IS development in Russians was evidenced for alleles of four genes: APOE, FGB, LPL and CMA1, where APOE gene involvement was evidenced for alleles of two polymorphic loci, -491T and -427C. Linkage analysis suggested that involvement of these loci in insusceptibility to IS is mutually independent.