Helsinki Sudden Death Study Research Articles

Prevalence of arrhythmia-associated gene mutations and risk of sudden cardiac death in the Finnish population

Background. Sudden cardiac death (SCD) remains a major cause of death in Western countries. It has a heritable component, but previous molecular studies have mainly focused on common genetic variants. We studied the prevalence, clinical phenotypes, and risk of SCD presented by ten rare mutations previously associated with arrhythmogenic right ventricular cardiomyopathy, long QT syndrome, or catecholaminergic polymorphic ventricular tachycardia.Methods. The occurrence of ten arrhythmia-associated mutations was determined in four large prospective population cohorts (FINRISK 1992, 1997, 2002, and Health 2000, n = 28,465) and two series of forensic autopsies (The Helsinki Sudden Death Study and The Tampere Autopsy Study, n = 825). Follow-up data were collected from national registries.Results. The ten mutations showed a combined prevalence of 79 per 10,000 individuals in Finland, and six of them showed remarkable geographic clustering. Of a total of 715 SCD cases, seven (1.0%) carried one of the ten mutations assayed: three carried KCNH2 R176W, one KCNH2 L552S, two PKP2 Q59L, and one RYR2 R3570W.Conclusions. Arrhythmia-associated mutations are prevalent in the general Finnish population but do not seem to present a major risk factor for SCD, at least during a mean of 10-year follow-up of a random adult population sample.

Age-dependent interaction of apolipoprotein E gene with eastern birthplace in Finland affects severity of coronary atherosclerosis and risk of fatal myocardial infarction—Helsinki Sudden Death Study

Background. Mortality from coronary heart disease (CHD) has been constantly higher in eastern late settlement regions compared to western early settlements in Finland, unrelated to classical risk factors. In line with this, eastern birthplace was an age-dependent predictor of severe coronary atherosclerosis and pre-hospital sudden coronary death among male residents of Helsinki. We investigated a possible interaction of apolipoprotein E (APOE) gene with birthplace on the risk of myocardial infarction (MI) and coronary atherosclerosis.Method. APOE genotypes were analyzed in the Helsinki Sudden Death Study series comprising out-of-hospital deaths among males aged 33–70 years (n = 577), who were born in high (east, n = 273) or low (west, n = 304) CHD mortality area.Results. Eastern-born men ≤ 55 years carried 30% more often (P = 0.017) and older men 40% less often (P = 0.022) the APOE ϵ4 allele compared to western-born men (P = 0.003 for birthplace-by-age interaction). In multivariate analysis, the ϵ4 allele associated with the risk of out-of-hospital MI (odds ratio 2.58; 95% CI 1.20–5.55; P = 0.016) only in eastern-born men and with advanced atherosclerosis in both regions of origin, respectively.Conclusions. Birthplace-bound risk of CHD was age-dependently modified by APOE ϵ4 allele, suggesting genetic differences in CHD susceptibility between early and late settlement regions in Finland and providing one explanation for the eastern high mortality.

Common Genetic Variants Associated with Sudden Cardiac Death: The FinSCDgen Study

BackgroundSudden cardiac death (SCD) accounts for up to half of cardiac mortality. The risk of SCD is heritable but the underlying genetic variants are largely unknown. We investigated whether common genetic variants predisposing to arrhythmia or related electrocardiographic phenotypes, including QT-interval prolongation, are associated with increased risk of SCD.Methodology/Principal FindingsWe studied the association between 28 candidate SNPs and SCD in a meta-analysis of four population cohorts (FINRISK 1992, 1997, 2002 and Health 2000, n = 27,629) and two forensic autopsy series (The Helsinki Sudden Death Study and The Tampere Autopsy Study, n = 694). We also studied the association between established cardiovascular risk factors and SCD. Causes of death were reviewed using registry-based health and autopsy data. Cox regression and logistic regression models were adjusted for age, sex, and geographic region. The total number of SCDs was 716. Two novel SNPs were associated with SCD: SCN5A rs41312391 (relative risk [RR] 1.27 per minor T allele, 95% CI 1.11–1.45, P = 3.4×10−4) and rs2200733 in 4q25 (RR 1.28 per minor T allele, 95% CI 1.11–1.48, P = 7.9×10−4). We also replicated the associations for 9p21 (rs2383207, RR 1.13 per G allele, 95% CI 1.01–1.26, P = 0.036), as well as for male sex, systolic blood pressure, diabetes, cigarette smoking, low physical activity, coronary heart disease, and digoxin use (P<0.05).Conclusions/SignificanceTwo novel genetic variants, one in the cardiac sodium channel gene SCN5A and another at 4q25 previously associated with atrial fibrillation, are associated with SCD.

Bβ-Fibrinogen Gene Promoter –455 G/A Polymorphism Associates with Severity of Coronary Artery Stenosis in Male Victims of Sudden Pre-Hospital Death

Background and Purpose: Elevated fibrinogen levels are associated with the risk of atherosclerotic disease and affected by smoking. In haplotype analyses, the A-allele of the -455 G/A promoter polymorphism of the Bβ-fibrinogen gene (FGB) was most strongly associated with elevated fibrinogen levels. The association of the FGB –455 G/A polymorphism with coronary artery disease (CAD) and its complications have not been studied at the vessel-wall level. Methods: We measured coronary stenosis as well as coronary and aortic atherosclerotic areas in a prospective autopsy series of 300 middle-aged (33-69 years) men (the Helsinki Sudden Death Study). FGB -455 G/A genotype was determined by PCR. Results: Genotype distributions were 69.9%, 24.9%, and 5.2% for GG, GA and AA, respectively. In a logistic regression model with age, hypertension, diabetes, body mass index (BMI) and smoking as confounders, there was a significant association between the A-allele of FGB -455 G/A and >50.0% stenosis in coronary arteries (44.0% vs. 25.3 %, OR=2.37, 95% CI 1.25 − 4.48, p=0.008), compared to GG homozygotes. There was no significant genotype- by-smoking interaction on the severity of coronary artery stenosis although the FGB -455 G/A A-allele had a more pronounced effect on stenosis severity. The FGB -455 G/A genotype was not linked with the extent of coronary or aortic atherosclerosis or with myocardial infarction (MI). Conclusion: Carriers of the A-allele of the FGB –455 G/A polymorphism had more severe coronary artery stenosis but this genotype did not affect the extent of coronary or aortic atherosclerotic lesion areas.

Birthplace in area with high coronary heart disease mortality predicts the severity of coronary atherosclerosis among middle-aged Finnish men who had migrated to capital area: The Helsinki Sudden Death Study

Background. Reasons why eastern-born male Finns have higher coronary heart disease (CHD) mortality than do western-born men are still unsettled. Recently, eastern birthplace was found to be an independent predictor of pre-hospital sudden cardiac death (SCD) in the new low-mortality area of residence.Aim. To investigate the association of birthplace with high CHD mortality attributes to more severe coronary atherosclerosis among men migrated to the low-mortality capital area.Method. Coronary atherosclerosis was measured in 373 western-born and 314 eastern-born out-of-hospital male deaths aged 33–70 years in Helsinki (The Helsinki Sudden Death Study), covering 24.6% of male deaths within this age-group. CHD risk factors were obtained from an interview of a next of kin.Results. In multivariate analysis there was a strong birthplace-by-age interaction with atherosclerosis (P = 0.0005). Eastern-born men <54 years had larger areas of fatty streaks (P = 0.0195), fibrotic plaque (P = 0.0133), calcification (P = 0.0009), total plaque area (P = 0.0011), and greater stenosis (P = 0.0004) in the left coronary compared to western-born men, independent of CHD risk factors. Amongst older men (≥54 years) such an association no longer appeared.Conclusion. Higher CHD mortality among eastern-born men may be due to more severe coronary atherosclerosis independently of CHD risk factors, reflecting Finns' two-phase settlement history.

Interleukin 18 gene promoter polymorphism: a link between hypertension and pre-hospital sudden cardiac death: the Helsinki Sudden Death Study

The interleukin 18 (IL-18) gene has a single nucleotide promoter region (-137) G-to-C polymorphism (rs187238) which leads to attenuated transcriptional activity of the gene and to lower production of pro-atherogenic IL-18. The C allele of this polymorphism is associated with a lower risk of sudden cardiac death (SCD). We examined the process by which this polymorphism alters the risk of SCD and coronary artery disease (CAD) by analysing the interactions between this polymorphism and environmental factors. TaqMan 5' nuclease assay was used to genotype the study population of the Helsinki Sudden Death Study, comprising medicolegal autopsies of 700 men. According to adjusted logistic regression analysis, there was a significant interaction between IL-18 genotype and hypertension impacting on the risk of SCD due to coronary heart disease (CHD) (P = 0.011) and the severity of autopsy-verified CAD (P = 0.026). Among GG homozygotes, hypertension was a major risk factor for SCD due to CHD [adjusted odds ratio (OR) 3.75 with 95% CI 1.78-7.91, P < 0.001] and hypertension also associated with larger coronary atherosclerotic plaque areas (P = 0.002) and the occurrence of complicated plaques (adjusted OR 8.38 with 95% CI 2.39-29.33, P < 0.001). Among C allele carriers, hypertension was not a significant risk factor for CHD-related SCD or CAD and did not associate with the development of coronary atherosclerotic plaques. According to gene expression analysis of atherosclerotic tissue samples obtained from live patients, hypertension also interacted significantly with IL-18 genotype affecting the expression of IL-18 (P = 0.030) mRNA and interferon-gamma mRNA (P = 0.004). Hypertension interacts with IL-18 gene promoter -137 G/C polymorphism, affecting the risk of SCD and the development of coronary atherosclerosis.

Birthplace predicts risk for prehospital sudden cardiac death in middle-aged men who migrated to metropolitan area: The Helsinki Sudden Death Study

Background. Eastern-born male Finns, irrespective of their place of residence, have high mortality from coronary heart disease (CHD), and half of such deaths are sudden.Aim. To study whether eastern birthplace alone or combined with life-style factors predicts risk for prehospital sudden cardiac death (SCD) in the new (west) low-mortality area of residence.Method. Prospective case-control autopsy study of all (700) out-of-hospital deaths of men aged 35–69 years in metropolitan Helsinki during 1981–82 and 1991–92. Data on CHD risk factors were obtained for 405, of whom 149 died of SCD (cases) and 256 of other causes (controls).Results. A birthplace-by-age interaction with SCD (P=0.024) and with myocardial infarction (P=0.005) appeared. Men ≤54 years born in the east were more often victims of SCD (odds ratio 2.99, 95% confidence interval 1.38–6.49, P=0.006) than were men born in the west, independently of CHD risk factors. SCD was predicted also by alcohol consumption, age, smoking, and hypertension. Amongst older (>54 years) men no association with birthplace was any longer evident, but alcohol and socio-economic status predicted SCD.Conclusions. Birthplace-based risk for SCD suggests the contribution of early life environment or genetic east-west differences, reflecting Finns’ two-phase settlement history.

Interactions of Functional Apolipoprotein E Gene Promoter Polymorphisms With Smoking on Aortic Atherosclerosis

Apolipoprotein E gene (APOE) interacts with environmental factors in defining risk for atherosclerosis. We studied whether the APOE epsilon2/epsilon3/epsilon4 genotype or APOE promoter polymorphisms -219G/T and +113G/C might interact with smoking on the development of fatty streaks. We also studied the previously unknown effects of +113G/C on transcriptional activity. The fatty streak areas of aorta were measured morphometrically in subjects of the Helsinki Sudden Death Study. Within APOE epsilon3/epsilon3 subjects, there was a strong interaction between smoking and both -219G/T (P=0.009) and +113G/C (P=0.003) promoter polymorphisms on abdominal aorta fatty streak area: the -219T- and +113C-allele carriers had larger lesion areas compared with G/G (12.7% versus 5.9%, P=0.007; 12.9% versus 6.3%, P=0.010, respectively) within nonsmokers. Within smokers, the associations were inverse. Moreover, smoking increased the fatty streak area within -219G/G or +113G/G genotypes and -219G/+113G/epsilon3 haplotype carriers. Functional studies in reporter assay showed that in comparison with the +113G allele, the +113C allele had higher transcriptional activity and bound transcription factors from liver cell nuclear extract with significantly lower affinity. In middle-aged Finnish men with APOE epsilon3/epsilon3 genotype, the APOE promoter polymorphisms -219G/T and +113G/C interact with smoking in modulating aortic atherosclerosis. The +113G/C polymorphism has an effect on transcriptional activity.

COX-2 GENE PROMOTER POLYMORPHISM AND CORONARY ARTERY DISEASE IN MIDDLE-AGED MEN: THE HELSINKI SUDDEN DEATH STUDY

Cyclooxygenase (COX) catalyzes formation of prostaglandins that contribute to the inflammation in atherosclerosis. Our objective was to study whether the functional C variant of the −765G→C polymorphism in the human COX-2 gene associates with the severity of coronary atherosclerosis measured at the coronary artery level. The Helsinki sudden death study autopsy material (n = 300) comprised of Finnish men who died suddenly. The area of atherosclerotic lesions in the coronary arteries was quantitated, and coronary narrowing was measured. The occurrence of myocardial infarction (MI) was assessed. Genotyping was by restriction endonuclease analysis. Men carrying the minor C allele had larger areas of complicated lesions (P = .024) and a higher number of coronary arteries that had over 50% stenosis (P = .036) compared to men representing the common GG genotype. The COX-2 polymorphism was not associated with MI. Our data suggest that COX-2 may be involved in plaque growth.

Association Analysis of Allelic Variants of USF1 in Coronary Atherosclerosis

USF1 regulates the transcription of more than 40 cardiovascular related genes and is well established as a gene associated with familial combined hyperlipidemia, a condition increasing the risk for coronary heart disease. No detailed data, however, exists on the impact of this gene to the critical outcome at the tissue level: different types of atherosclerotic lesions. We analyzed the USF1 in 2 autopsy series of altogether 700 middle-aged men (the Helsinki Sudden Death Study) with quantitative morphometric measurements of coronary atherosclerosis. SNP rs2516839, tagging common USF1 haplotypes, associated with the presence of several types of atherosclerotic lesions, particularly with the proportion of advanced atherosclerotic plaques (P=0.02) and area of calcified lesions (P<0.001) of the coronary arteries. Importantly, carriers of risk alleles of rs2516839 also showed a 2-fold risk for sudden cardiac death (genotype TT versus CC; OR 2.10, 95% CI 1.17 to 3.75, P=0.04). The risk effect of rs2516839 was present also in aorta samples of the men. Our findings in this unique study sample suggest that USF1 contributes to atherosclerosis, the pathological arterial wall phenotype resulting in coronary heart disease and in its most dramatic consequence-sudden cardiac death.

Expression of sterol regulatory element-binding transcription factor (SREBF) 2 and SREBF cleavage-activating protein (SCAP) in human atheroma and the association of their allelic variants with sudden cardiac death

BackgroundDisturbed cellular cholesterol homeostasis may lead to accumulation of cholesterol in human atheroma plaques. Cellular cholesterol homeostasis is controlled by the sterol regulatory element-binding transcription factor 2 (SREBF-2) and the SREBF cleavage-activating protein (SCAP). We investigated whole genome expression in a series of human atherosclerotic samples from different vascular territories and studied whether the non-synonymous coding variants in the interacting domains of two genes, SREBF-2 1784G>C (rs2228314) and SCAP 2386A>G, are related to the progression of coronary atherosclerosis and the risk of pre-hospital sudden cardiac death (SCD).MethodsWhole genome expression profiling was completed in twenty vascular samples from carotid, aortic and femoral atherosclerotic plaques and six control samples from internal mammary arteries. Three hundred sudden pre-hospital deaths of middle-aged (33–69 years) Caucasian Finnish men were subjected to detailed autopsy in the Helsinki Sudden Death Study. Coronary narrowing and areas of coronary wall covered with fatty streaks or fibrotic, calcified or complicated lesions were measured and related to the SREBF-2 and SCAP genotypes.ResultsWhole genome expression profiling showed a significant (p = 0.02) down-regulation of SREBF-2 in atherosclerotic carotid plaques (types IV-V), but not in the aorta or femoral arteries (p = NS for both), as compared with the histologically confirmed non-atherosclerotic tissues. In logistic regression analysis, a significant interaction between the SREBF-2 1784G>C and the SCAP 2386A>G genotype was observed on the risk of SCD (p = 0.046). Men with the SREBF-2 C allele and the SCAP G allele had a significantly increased risk of SCD (OR 2.68, 95% CI 1.07–6.71), compared to SCAP AA homologous subjects carrying the SREBF-2 C allele. Furthermore, similar trends for having complicated lesions and for the occurrence of thrombosis were found, although the results were not statistically significant.ConclusionThe results suggest that the allelic variants (SREBF-2 1784G>C and SCAP 2386A>G) in the cholesterol homeostasis regulating SREBF-SCAP pathway may contribute to SCD in early middle-aged men.

COX‐2 Gene Promoter Polymorphism and Coronary Artery Disease in Middle‐Aged Men: The Helsinki Sudden Death Study

Cyclooxygenase (COX) catalyzes formation of prostaglandins that contribute to the inflammation in atherosclerosis. Our objective was to study whether the functional C variant of the −765G→C polymorphism in the human COX-2 gene associates with the severity of coronary atherosclerosis measured at the coronary artery level. The Helsinki sudden death study autopsy material (n = 300) comprised of Finnish men who died suddenly. The area of atherosclerotic lesions in the coronary arteries was quantitated, and coronary narrowing was measured. The occurrence of myocardial infarction (MI) was assessed. Genotyping was by restriction endonuclease analysis. Men carrying the minor C allele had larger areas of complicated lesions (P = .024) and a higher number of coronary arteries that had over 50% stenosis (P = .036) compared to men representing the common GG genotype. The COX-2 polymorphism was not associated with MI. Our data suggest that COX-2 may be involved in plaque growth.

Neuropeptide Y signal peptide Pro7 substitution protects against coronary artery atherosclerosis: The Helsinki Sudden Death Study

Objective Neuropeptide Y (NPY) has a single nucleotide polymorphism at T1128C, leading to change of Leucine7 to Proline7. The Leu7Pro substitution has been linked to cardiovascular disease, but it is unknown whether the Pro7 allele is associated with increased or decreased risk of coronary heart disease (CHD). The aim of the present study was to investigate the association of the Leu7Pro polymorphism with coronary atherosclerosis and its consequences. Methods We studied two autopsy series comprising 700 unselected middle-aged Caucasian men (Helsinki Sudden Death Study) who had died suddenly out of hospital. Areas of coronary artery atherosclerosis, narrowings of coronary arteries, and presence of myocardial infarction and/or coronary thrombosis were analyzed. All information including CHD risk factor data was obtained from 410 men. Results NPY genotype distribution was Leu7/Leu7 = 89.8%, Leu7/Pro7 = 10.0% and Pro7/Pro7 = 0.2%). Although the Pro7 allele was associated with reported hypertension ( p = 0.03), the men carrying Pro7 allele had lower area of fatty streaks ( p = 0.04), fibrotic lesions ( p = 0.07) and complicated lesions ( p = 0.004) in the left anterior descending (LAD) coronary artery and also less severe LAD narrowings ( p = 0.04) than men with the Leu7/Leu7 genotype. Supporting a protective role for the Pro7 allele against atherosclerosis, only 1 out of 46 men (2%) with coronary thrombosis carried the Pro7 allele ( p = 0.08 compared to men dying of other causes). This association weakened (OR 0.18 for Pro7 versus Leu7/Leu7, p = 0.16) when adjusted for all available CHD risk factors. Conclusions NPY Pro7 substitution protects middle-aged men from coronary artery atherosclerosis and might decrease the risk of acute coronary events.

Interleukin-18 promoter polymorphism associates with the occurrence of sudden cardiac death among Caucasian males: The Helsinki Sudden Death Study

Objective The increased plasma concentrations of pro-atherogenic and cardiomyocyte hypertrophic cytokine interleukin 18 (IL-18) predict mortality in patients with coronary heart disease (CHD) in addition to predicting the outcome of heart failure. The IL-18 gene has a functional −137 G/C polymorphism (rs187238) in the promoter region. The C allele carriage is associated with attenuated IL-18 production. The effect of IL-18 genotype on SCD is unknown. We studied the association of the IL-18 gene −137 G/C polymorphism with the occurrence of sudden cardiac death (SCD). Methods Using the TaqMan 5′ nuclease assay, we genotyped two independent consecutive and prospective autopsy series which were included in the Helsinki Sudden Death Study. Results Of the 663 men, 359 (54.1%) had the wild-type GG-genotype, 261 (39.4%) were heterozygotes (CG) and 43 (6.5%) were CC homozygotes. Compared to the GG homozygotes, the C allele carriers (i.e. subjects having CC or CG genotypes) had a lower adjusted risk for SCD from any cause (odds ratio [OR] 0.49; 95% confidence interval [CI], 0.31–0.77, p = 0.002), for SCD due to CHD (OR 0.51; 95% CI, 0.32–0.82, p = 0.005), and for SCD caused by non-coronary heart diseases (OR 0.34; 95% CI 0.13–0.90, p = 0.030). Conclusion IL-18 promoter −137 G/C polymorphism, which regulates the expression of IL-18, is an important predictor of SCD from any cause as well as SCD in patients with and without underlying CHD.

Age-dependent association between hepatic lipase gene C-480T polymorphism and the risk of pre-hospital sudden cardiac death: The Helsinki Sudden Death Study

Objective We investigated the association between hepatic lipase (HL) C-480T polymorphism and the risk of acute myocardial infarction (AMI) as well as pre-hospital sudden cardiac death (SCD). Methods Seven hundred sudden or unnatural pre-hospital deaths of middle-aged (33–70 years, mean 53 years) Caucasian Finnish men were subjected to detailed autopsy (Helsinki Sudden Death Study). Genotype data were obtained for 682 men. Results In logistic regression analysis with age, body mass index, hypertension, diabetes, smoking and alcohol consumption as covariates, men with the TT genotype had an increased risk for SCD and AMI compared to CC carriers (OR = 3.0, P = 0.011; and OR = 3.7, P = 0.003). There was a significant age-by-genotype interaction ( P < 0.05) on the risk of SCD. Compared to CC genotype carriers, the association between the TT genotype and SCD was particularly strong ( P = 0.001) among men <53 years of age, but this association was non-significant among older men. This was mainly due to a strong association between the TT genotype and AMI due to severe coronary disease in the absence of thrombosis. Carriers of the TT genotype were more likely to have severe coronary stenoses (≥50%) than men with the CT or CC genotype ( P = 0.019). Conclusions The results suggest that HL C-480T polymorphism is a strong age-dependent risk factor of SCD in early middle-aged men.

Toll‐like receptor 4 polymorphism is associated with coronary stenosis but not with the occurrence of acute or old myocardial infarctions

Objective. Atherosclerosis is considered to be a chronic inflammatory disease. Toll‐like receptor 4 (TLR‐4), a key mediator in activating inflammatory cascade, has an A‐to‐G functional polymorphism that changes aspartic acid to glycine at position 299. TLR‐4 is activated by, for example, lipopolysaccharides. The purpose of this study was to investigate the role of a common Asp299Gly polymorphism of the TLR‐4 gene in atherosclerosis. Material and methods. The study comprised autopsy material from 657 men (the Helsinki Sudden Death Study; mean age 53, range 33–70 years). Results. Fewer G‐allele carriers had 3‐vessel coronary artery disease compared with AA homozygotes (OR 0.32; 95 % CI, 0.12–0.88, p = 0.027), and they also had a lower mean value for maximal coronary stenosis (p = 0.019). TLR‐4 polymorphism was not significantly associated with the occurrence of acute or old myocardial infarction (MI). Conclusions. The G allele of the TLR‐4 gene, which is associated with a lower inflammation response, was associated with a lower risk of coronary stenosis but not with the occurrence of MI and hence is not a major factor in the development of coronary atherosclerosis.

Radiographic Assessment of Dental Health in Middle-aged Men Following Sudden Cardiac Death

Poor oral health has been suggested to be a risk factor for myocardial infarction. To study if dental pathology might predispose to pre-hospital sudden cardiac death, and using a sum index of panoramic tomography findings, we compared the oral health of middle-aged (33-69 yrs) male victims (Helsinki Sudden Death Study) of sudden cardiac death (n = 117) with that of controls, who died of non-cardiac diseases (n = 63) or suffered unnatural sudden death (n = 120). The mean number of teeth was 15.2, and 17.4% of the men were edentulous. Frequent age-associated findings in dentate victims were fillings (79.9%), horizontal bone loss (72.1%), periapical lesions (45.6%), residual roots (38.2%), and vertical pockets (30.9%). In multivariate analysis with coronary heart disease risk factors and number of teeth as covariates, poor oral health was associated (p = 0.053) with the risk of sudden cardiac death along with age, smoking, and body mass index. This association was especially strong (p = 0.009) among victims < 50 yrs.

Matrix metalloproteinase3 and 9 gene promoter polymorphisms: joint action of two loci as a risk factor for coronary artery complicated plaques

Objective: Matrix metalloproteinases 3 and 9 (MMP3 and MMP9) are present in atherosclerotic plaques and co-operate in the degradation of the fibrous cap of the atheroma, leading to fissuring and ultimately to acute coronary thrombosis. The functional genetic polymorphisms in the promoters of MMP3 and MMP9, which lead to low- and high-transcription activity genotypes, have been shown to be associated with myocardial infarction and angiographically measured atherosclerosis individually, whereas their effects in combination are not yet known. In order to assess the two disease loci simultaneously, we investigated the association of combined low and high promoter activity genotypes with different types of coronary lesions in an autopsy cohort of 300 Caucasian males aged 33–69 years (Helsinki Sudden Death Study). Methods: Genotyping at these loci was performed by PCR, restriction enzyme digestion and minisequencing, and areas of the coronary wall covered with atherosclerotic lesions were measured using computer-assisted morphometry. Results: In analysis of covariance (ANCOVA) with age, body mass index, hypertension, diabetes, smoking and alcohol consumption as covariates, a significant interaction between the MMP3 and MMP9 genotypes was observed on area of complicated lesions ( P = 0.012). Men with high promoter activity genotypes for both loci had, on average, more than two times larger area of complicated lesions (250%) compared with those men who had low promoter activity genotypes ( P = 0.008), but these loci showed no association with myocardial infarction. Conclusions: The joint action of two susceptibility loci, rather than single MMP genes alone, and the particular combination of MMP3 and MMP9 genotypes present at these loci may contribute to heterogeneity in the presentation of atherosclerosis.

Association of paraoxonase-1 M55L genotype and alcohol consumption with coronary atherosclerosis: the Helsinki Sudden Death Study.

High-density lipoprotein (HDL) level is inversely correlated with coronary heart disease risk. Paraoxonase-1 (PON1) is an HDL-associated anti-atherogenic enzyme. The activity of PON1 is affected by the methionine for leucine substitution at position 55 (M55L) and increased during regular moderate alcohol consumption, consistent with increased HDL cholesterol concentration. We related the PON1 M55L genotypes to the extent of atherosclerosis in left anterior descending coronary artery (LAD) in alcohol abstainers (0-1 g of alcohol/day), moderate consumers (1-36 g of alcohol/day) and drinkers (> 36 g of alcohol/day). The study subjects included an autopsy series of total of 700 middle-aged Finnish men from the Helsinki Sudden Death Study. The LAD was stained for fat and the areas covered with fatty streaks and fibrotic and complicated plaques were measured. Data on coronary artery disease risk factors were obtained from relatives or close friends of the deceased. Compared to the LL homozygotes, carriers of the M55 allele tended to have larger areas of atherosclerotic lesions, the size of which decreased dose-dependently by reported alcohol consumption. Moderate consumers carrying the M55 allele had significantly larger complicated plaques compared to the LL homozygotes drinking as much (P = 0.009). Among the M55 allele carriers, drinkers showed significantly smaller areas of fatty streaks compared to abstainers (P = 0.042) and moderate consumers (P < 0.001) (for the PON1 genotype by alcohol interaction, P = 0.078). Similarly, drinkers with the M55 allele also had statistically significantly smaller areas of complicated lesions than moderate consumers with the M55 allele (P < 0.0001) (for the PON1 genotype by alcohol interaction, P = 0.009). The areas of atherosclerotic lesions in LAD appear to be dependent on the amount of alcohol consumption, especially in men carrying the PON1 M55 allele.

Platelet membrane collagen receptor glycoprotein VI polymorphism is associated with coronary thrombosis and fatal myocardial infarction in middle-aged men

Glycoprotein VI is a platelet collagen receptor binding to subendothelial collagen after a rupture of an atherosclerotic plaque. The GPVI gene is polymorphic with several SNPs and the T13254C polymorphism predicting amino acid substitution (serine to proline) has been associated with the risk of MI in a preliminary study. We studied the association of the GPVI T13254C with fatal myocardial infarction (MI) and coronary artery disease among the 300 men of the Helsinki Sudden Death Study (HSDS). Genotype frequencies were 77.9% for TT, 20.7% for CT and 1.4% for CC. We found a significant association ( P = 0.02) between the C-allele carriers (CT or CC) and coronary thrombosis (OR 2.5, 95% CI: 1.05–6.2). There was also a tendency ( P = 0.07) for an association between the C-allele and acute myocardial infarction (AMI) (OR 2.2). The average area of complicated coronary lesions was also significantly ( P = 0.01) larger in carriers compared to non-carriers of the C-allele. Our findings support previous results on the role of this GPVI polymorphism, or another linked polymorphism, as a possible predictor of the risk of coronary thrombosis.