Verification of Single Nucleotide Polymorphisms rs34554140, rs6670279, and rs6874185 as Novel Molecular Genetic Markers of Sudden Cardiac Death

The aim of the study was to explore the association between sudden cardiac death (SCD) and single nucleotide polymorphisms (SNPs) rs34554140, rs6670279, and rs6874185 from the list of potential molecular genetic markers of SCD, obtained in our earlier genome-wide allelotyping on pooled DNA samples.

Materials and Methods

The study is based on the case-control principle. The SCD group included 438 deceased residents of Novosibirsk (average age - 53.2±9.1 years; men - 72.7%, women - 28.3%) with the main postmortem diagnoses of acute circulatory failure or acute coronary failure, which met the criteria of SCD established by the European Society of Cardiology. The control group included 435 live subjects enrolled in the international projects HAPIEE and MONICA (average age - 53.2±8.9 years; men - 70.0%, women - 30.0%). DNA was isolated by phenol-chloroform extraction from the myocardial tissue in the SCD group and from the venous blood in the control group. Genotyping was performed by polymerase chain reaction with subsequent analysis of restriction fragment length polymorphism in a polyacrylamide gel.

Results

The frequencies of the genotypes of SNPs rs34554140, rs6670279, and rs6874185 in the control group correspond to those predicted by the Hardy-Weinberg equilibrium (c²=0.98, 0.009, 3.39, respectively). The AA genotype of rs34554140 is associated with an increased risk of SCD (p=0.002; OR=1.85; 95% CI 1.26-2.71). The AT genotype has a protective effect against SCD (p=0.001; OR=0.53; 95% CI 0.36-0.78). In subgroups separated by gender and age, the differences persist in the subgroups of men, women, and individuals under 50 years old (p<0.05). The AA genotype of rs6670279 is associated with an increased risk of SCD (p=0.005; OR=1.54; 95% CI 1.15-2.06). The AT genotype has a protective effect against SCD (p=0.047; OR=0.73; 95% CI 0.54-0.98). When distributed by sex and age, the differences persist in the subgroups of men, individuals above 50 years old, and men above 50 years old (p<0.05). There were no significant differences in the frequencies of genotypes and alleles of rs6874185 between the SCD and control groups, even after the subgroups specified by gender and age were compared (p>0.05).

Conclusion

The association of single nucleotide polymorphisms rs34554140 and rs6670279 with SCD was confirmed. In contrast, no association of rs6874185 with SCD was detected.

Association of SCN5A gene polymorphism with dilated cardiomyopathy

Subjects and methods. The study included patients with IDC (group 1; n=111, 89.2% men, average age 51.7±9.7 years) and ICM (group 2; n=110, 91.5% men, average age 58.7±8.4 years). All patients (IDC and ICM) underwent coronary angiography. Based on the anamnesis data and instrumental studies, those patients who could be said to have no risk factors for the development of dilatation of the heart cavities were identified in the group 1. And those patients who were reliably diagnosed with coronary artery disease were in the group 2, that is, dilatation of the heart cavities is due to a previous myocardial infarction, existing angina pectoris. The control group (n=121, average age 53.6±4.8 years) included patients who had no manifestations of cardiovascular diseases. The patients underwent laboratory and instrumental studies, as well as molecular and genetic studies of the A/G polymorphism of the SCN5A gene (rs1805124).

Results. In the group with IDC 51.4% of patients were carriers of the common homozygous AA genotype, the heterozygous AG genotype-40.5%, and the rare homozygous GG genotype-8.1%. In the control group 63.3% of patients were identified as carriers of a homozygous genotype by a common allele, and 33.5% were carriers heterozygous genotype, and homozygous genotype for a rare allele – 3.2%. The analysis revealed a statistically significant decrease in the frequency of carrying the homozygous AA genotype in patients with IDC compared to the control group of the rs1805124 polymorphism of the SCN5A gene. In the group of patients with ICM, the А allele (69.5% vs. 80.1%, p=0.003) and the AA genotype (50.9% vs. 63.3%, p=0.030) were significantly less common than in the control group. The rare homozygous GG genotype was statically more common in patients with ICM compared to the control group (11.8% vs. 3.2%, p=0.004). Also, the G allele in the group of patients with ICM was detected statically significantly more often than in the control group (30.5% vs. 19.9%, p= 0.003).

Conclusion. The polymorphic locus rs1805124 of the SCN5A gene is associated with both IDC and ICM. Homozygous genotype AA and allele A are conditionally protective factors for the development of these conditions in men.

[Association of rs3025058 polymorphism with the development of stroke in patients with cardiovascular pathology]

AIM

To study the association of single-nucleotide polymorphismrs3025058(5а/6а) with the development of stroke in patients of the East Siberian population with cardiovascular pathology and risk factors for its development.

MATERIALS AND METHODS

The study involved 260 patients with stroke (age [57.0; 51.062.0]) and 272 patients of the control group (age [55.0; 51.062.0]). Among the patients who underwent stroke, 157 men and 103 women. The control group included 170 men and 102 women. The examination of the main group included: collection of complaints, anamnesis, clinical examination, computed tomography of the brain, electrocardiography, echocardioscopy, ultrasound duplex scanning of the extracranial brachiocephalic arteries, 24-hour monitoring of blood pressure and heart rate, analysis of the blood coagulation system. The patients of the main group had the following cardiovascular pathology and risk factors: arterial hypertension, paroxysmal supraventricular tachycardias, dyslipidemia, atherosclerosis of extracranial brachiocephalic arteries, disorders of the hemostasis system. The control group was examined within the framework of the international project HAPIEE. Molecular genetic research was carried out by real-time PCR. Statistical processing of the material was carried out using the Statistica for Windows 7.0, Excel and SPSS 22 application software.

RESULTS

The study established statistically significant associations between the 5a/5a genotype and the 5a allele and stroke in the general group of patients, as well as in the subgroup of men, subgroups of patients with extracranial brachiocephalic arteries atherosclerosis and dyslipidemia. In the subgroup of patients with cardiac arrhythmias, statistically significant results were obtained only for allele 5a, and in the subgroup of women with stroke, subgroups of patients with arterial hypertension and hypercoagulation, no significant associations ofrs3025058(5a/6a) polymorphism with stroke were found.

CONCLUSION

Genotype 5a/5a and allele 5a of the single-nucleotide polymorphismrs3025058(5а/6а) increase the risk of stroke in individuals from the East Siberian population, including those in the presence of such risk factors as extracranial brachiocephalic arteries atherosclerosis and dyslipidemia.

Association of rs556621 Polymorphism with Development of Stroke in Patients with Cardiovascular Pathology

Aim. To study the association of single nucleotide polymorphism rs556621 (G> T) with development of stroke in patients of the East Siberian population with cardiovascular pathology and risk factors.

Material and methods. The study involved 260 patients (157 men and 103 women) with stroke (mean age 57.0 [51.0-62.0]) and 272 patients (170 men and 102 women) of the control group (mean age 55.0 [51.0-62.0]). The examination of the main group included: collection of complaints, anamnesis, clinical examination, computed tomography of the brain, electrocardiography, echocardioscopy, ultrasound duplex scanning of extracranial brachiocephalic arteries, daily blood pressure and heart rate monitoring, analysis of the blood coagulation system. The patients of the main group have arterial hypertension, paroxysmal supraventricular tachycardias, dyslipidemia, atherosclerosis of the brachiocephalic arteries, disorders of the hemostatic system. The control group was studied in the framework of the HAPIEE international project. Molecular genetic research was performed by real-time polymerase chain reaction.

Results. There were no statistically significant differences in the frequencies of genotypes and single nucleotide polymorphism rs556621 alleles (G>T) in the subgroup of patients with stroke and those in the control group. The frequency of the rare TT genotype among patients with stroke was 13.3%±4.16, among healthy individuals – 8.8±3.37% (p=0.1). Gender differences when comparing the frequencies of genotypes and alleles were also not detected (p>0.05). The frequencies of the TT genotype were approximately the same in the subgroup of patients with arterial hypertension (13.1%±4.22) and in the control group (7.4±5.25%; p>0.05). No significant differences were observed in the frequencies of the rare genotype of the studied polymorphism in the subgroup of patients with supraventricular tachycardias (20.0±14.37%), hypercoagulability (15.9±7.64%) and the control group (8.8±3.37%), p>0.05. A statistically significant relationship was found between the rare genotype TT of single nucleotide polymorphism rs556621 (G>T) and the development of stroke in patients with dyslipidemia and atherosclerotic lesions of the coronary arteries (p=0.041; odds ratio 1.86, 95% confidence interval 1.02-3.41).

Conclusion. The genotype of TTs of single nucleotide polymorphism rs556621 (G> T) increases the risk of developing stroke in patients with dyslipidemia and atherosclerosis of the brachiocephalic arteries compared with carriers of the GG and GT genotypes. The obtained data are recommended to be considered when prescribing lipid-lowering and antithrombotic therapy.