Alun Evans

Synergistic effects of angiotensin-converting enzyme and angiotensin-II type 1 receptor gene polymorphisms on risk of myocardial infarction

We reported from our previous multicentre case-control study that the deletion (D) polymorphism of the gene encoding angiotensin-converting enzyme (ACE) was associated with increased risk of myocardial infarction. The main function of ACE is to convert angiotensin I into angiotensin II, which exerts its known cellular actions through the angiotensin II AT1 receptor subtype (AGT1R). We have now investigated the role of a common polymorphism of the AT1 receptor gene (an A-->C transversion at position 1166 of AGT1R) and looked for an interaction between ACE and AGT1R gene polymorphisms on the risk of myocardial infarction. We analysed DNA from 613 patients with myocardial infarction and 723 age-matched population controls. We found a significant interaction between ACE and AGT1R gene polymorphisms; the odds ratio for myocardial infarction associated with the ACE DD genotype was 1.05 (95% CI 0.75-1.49) for subjects without the AGT1R C allele, 1.52 (1.06-2.18) in AC heterozygotes, and 3.95 (1.26-12.4) in CC homozygotes (test for trend, p < 0.02). Among patients defined as low risk by traditional risk factors (serum apolipoprotein B < 1.25 g/L, body-mass index < 26 kg/m2) the interaction was even stronger (odds ratios 1.64 [0.68-3.92], 7.03 [2.61-19.0], and 13.3 [p = 0.05], respectively). These findings, if confirmed, could have clinical implications for the prevention and treatment of coronary heart disease.

Alcohol intake modulates the effect of a polymorphism of the cholesteryl ester transfer protein gene on plasma high density lipoprotein and the risk of myocardial infarction.

A polymorphism of the CETP gene (CETP/TaqIB) with two alleles B1 (60%) and B2 (40%) has been investigated in relation to lipid variables and the risk of myocardial infarction in a large case-control study (ECTIM) of men aged 25-64. No association was observed between the polymorphism and LDL or VLDL related lipid variables. Conversely, B2 carriers had reduced levels of plasma CETP (P < 0.0001) and increased levels of HDL cholesterol (P < 0.0001) and of other HDL related lipid variables. The effects of the polymorphism on plasma CETP and HDL cholesterol were independent, suggesting the presence of at least two functional variants linked to B2. A search for these variants on the coding sequence of the CETP gene failed to identify them. The effect of B2 on plasma HDL cholesterol was absent in subjects drinking < 25 grams/d of alcohol but increased commensurably, with higher values of alcohol consumption (interaction: P < 0.0001). A similar interaction was not observed for plasma CETP. The odds-ratio for myocardial infarction of B2 homozygotes decreased from 1.0 in nondrinkers to 0.34 in those drinking 75 grams/d or more. These results provide the first demonstration of a gene-environment interaction affecting HDL cholesterol levels and coronary heart disease risk.

Deletion polymorphism in angiotensin-converting enzyme gene associated with parental history of myocardial infarction

In a European study an insertion (I)/deletion (D) polymorphism in the angiotensin converting enzyme (ACE) gene has been shown to be associated with the risk of myocardial infarction (MI). In the same study, we investigated the association of the polymorphism with a parental history of fatal MI. There was an excess of both DD (odds ratio 2.6, p = 0.02) and ID (odds ratio = 1.9, p = 0.08) genotypes among those having a parental history of MI, confirming that genetic variation in the ACE locus could be involved in the risk of MI.

Association of hypertensive status and its drug treatment with lipid and haemostatic factors in middle-aged men: the PRIME study.

Aims: To assess the association of hypertensive status and antihypertensive drug treatment with lipid and haemostatic levels in middle-aged men.Methods and results: Hypertensive status, antihypertensive drug treatment, total and high-density lipoprotein (HDL) cholesterol, triglyceride, apoproteins A-I and B, lipoparticles LpA-I, LpE:B and Lp(a), fibrinogen, plasminogen activator inhibitor-1 (PAI-1) activity and factor VII were assessed in a sample of men 50–59 years living in France (n = 7050) and Northern Ireland (n = 2374). After adjustment for age, body mass index, smoking status, educational level, country, alcohol drinking and hypolipidaemic drug treatment, untreated hypertensive subjects had higher levels of total cholesterol, triglyceride, apoproteins A-I and B and PAI-I activity than normotensive subjects. On univariate analysis, diuretics decreased total and HDL-cholesterol and apoproteins A-I and B; those differences remained after multivariate adjustment. Treatment with beta-blockers decreased total and HDL-cholesterol, apoprotein A-I and LpA-I, and this effect remained after multivariate adjustment. Calcium channel blockers decreased total cholesterol and apoproteins A-I and B; those differences remained significant after multivariate adjustment. ACE inhibitors decreased total cholesterol, triglycerides, apoprotein B and LpE:B; and this effect remained after multivariate adjustment. Analysis of the subjects on monotherapy showed beta-blockers to decrease total cholesterol and HDL parameters and angiotersin-converting enzyme (ACE) inhibitors to decrease low-density lipoprotein (LDL)-related parameters, while no effect was found for the other antihypertensive drugs.Conclusions: Hypertensive status is associated with an unfavourable lipid and haemostatic profile in middle-aged men. Antihypertensive treatment with beta-blockers decreases HDL parameters, whereas treatment with ACE inhibitors appears to decrease total cholesterol and LDL-related parameters.

Influence of cholesteryl ester transfer protein, peroxisome proliferator–activated receptor α, apolipoprotein E, and apolipoprotein A-I polymorphisms on high-density lipoprotein cholesterol, apolipoprotein A-I, lipoprotein A-I, and lipoprotein A-I:A-II concentrations: the Prospective Epidemiological Study of Myocardial Infarction study

The plasma level of high-density lipoprotein cholesterol (HDL-C) is known to be inversely associated with cardiovascular risk. However, besides lifestyle, gene polymorphism may influence the HDL-C concentration. The aim of this study was to investigate the possibility of interactions between CETP, PPARA, APOE, and APOAI polymorphisms and HDL-C, apolipoprotein (apo) A-I, lipoprotein (Lp) A-I, and Lp A-I:A-II in a sample selected from the Prospective Epidemiological Study of Myocardial Infarction (PRIME) study population who remained free of cardiovascular events over 5 years of follow-up. Healthy individuals (857) were randomly selected for genotyping the PRIME study subjects. The population was selected so as to provide 25% of subjects in the lowest tertile of HDL-C (< or = 28 mg/dL) in the whole PRIME study sample, 25% of subjects in the highest tertile of HDL-C (> or = 73 mg/dL), and 50% of subjects in the medium tertile of HDL-C (28-73 mg/dL). Genotyping was performed by using a polymerase chain reaction system with predeveloped TaqMan allelic discrimination assay. The CETP A373P rare allele c was less frequent in the group of subjects with high HDL-C, apo A-I, Lp A-I, and Lp A-I:A-II concentrations. Apolipoprotein A-I and Lp A-I were also found to be higher in the presence of the epsilon2 allele coding for APOE. The effect of the CETP A373P rare allele c on HDL-C was independent of all tested parameters except triglycerides. The respective effect of these polymorphisms and triglycerides on cardiovascular risk should be evaluated prospectively.

Lack of association of genetic variants in the LRP8 gene with familial and sporadic myocardial infarction.

Coronary artery disease (CAD) and myocardial infarction (MI) have a genetic basis, but the precise genetic underpinning remains controversial. Recently, an association of the LRP8 R952Q polymorphism (rs5174) with familial premature CAD/MI was reported. We analysed rs5174 (or the perfect proxy rs5177) in 1,210 patients with familial MI and 1,015 controls from the German MI Family study, in 1,926 familial CAD (1,377 with MI) patients and 2,938 controls from the Wellcome Trust Case Control Consortium (WTCCC) MI/CAD cohort, in 346 CAD patients and 351 controls from the AtheroGene study and in 295 men with incident CAD and 301 controls from the Prospective Epidemiological Study of MI study and found no evidence for association in any of the populations studied. In the WTCCC and the German MI Family studies, additional single-nucleotide polymorphisms in the LRP8 gene were analysed and displayed no evidence for association either.

Ideal Cardiovascular Health and Incident Cardiovascular Disease: Heterogeneity Across Event Subtypes and Mediating Effect of Blood Biomarkers: The PRIME Study

Background The aim of this study was to investigate whether the association between baseline cardiovascular health (CVH) and incident cardiovascular disease differs according to coronary heart disease (CHD) and stroke subtypes, and to assess the mediating effect of inflammatory and hemostatic blood biomarkers. Methods and Results The association of ideal CVH with outcomes was derived in 9312 middle‐aged men from Northern Ireland and France (whole cohort) in multivariable Cox proportional hazards regression analysis. The mediating effect of baseline inflammatory and hemostatic blood biomarkers was evaluated in a case–control study nested within the cohort after 10 years of follow‐up. After a median follow‐up of 10 years, 614 first CHD events and 117 first stroke events were adjudicated. Compared with those with poor CVH, those with an ideal CVH profile at baseline had a 72% lower risk of CHD (hazard ratio=0.28; 95% confidence interval, 0.17; 0.46) and a 76% lower risk of stroke (hazard ratio =0.24; 95% confidence interval, 0.06; 0.98). The magnitude of the risk reductions was similar for incident angina and myocardial infarction, but was lower for ischemic stroke. In the controls, the mean concentrations of high‐sensitivity C‐reactive protein, IL‐6, and fibrinogen decreased with higher CVH status. Furthermore, the association of behavioral CVH with incident CHD was partly mediated by high‐sensitivity C‐reactive protein (16.69%), IL‐6 (8.52%), and fibrinogen (7.30%) Conclusions Our study shows no clear heterogeneity in the association of baseline CVH with the main subtypes of cardiovascular disease. This supports a universal promotion of ideal CVH for all cardiovascular disease subtypes. Furthermore, our mediation analysis suggests that the lower risk of CHD associated with ideal CVH is partly mediated by lower inflammatory and hemostatic blood biomarkers.

The genetic contribution to the onset of acute coronary heart disease

The genetic factors associated with a predisposition to acute coronary syndromes such as myocardial infarction (MI) and sudden death may act through chronic processes, mainly atherosclerosis, hypertension, vascular and cardiac hypertrophy and endothelial dysfunction; or acutely, by promoting plaque rupture, thrombosis or vasoconstriction. These pathological manifestations are tightly interconnected. Chronic processes modify the probability of the occurrence of acute manifestations and, conversely, plaque rupture and thrombosis may contribute to accelerated evolution of the atheromatous plaque. The interplay of these different factors may affect the risk of an individual developing an acute coronary event in response to a triggering factor.