Insertion/deletion (I/D) polymorphism at the locus for angiotensin I-converting enzyme and myocardial infarction

Distribution of allele frequencies for genes associated with physical activity and/or physical capacity in a homogenous Norwegian cohort- a cross-sectional study

BACKGROUND

There are large individual differences in physical activity (PA) behavior as well as trainability of physical capacity. Heritability studies have shown that genes may have as much impact on exercise participation behavior as environmental factors. Genes that favor both trainability and participation may increase the levels of PA. The present study aimed to assess the allele frequencies in genes associated with PA and/or physical capacity, and to see if there is any association between these polymorphisms and self-reported PA levels in a cohort of middle-aged Norwegians of Scandinavian descent (n = 831; mean age mean age (± SD) 55.5 ± 3.8 years).

RESULTS

The genotype distributions of the ACTN3 R577X, ACE I/D and MAOA uVNTR polymorphisms were similar to other populations of European descent. When comparing the genotype distribution between the low/medium level PA group (LMPA) and high level PA groups (HPA), a significant difference in ACTN3 577X allele distribution was found. The X allele frequency was 10% lower in the HPA level group (P = 0.006). There were no differences in the genotype distribution of the ACE I/D or MAOA uVNTR polymorphism. Education and previous participation in sports or outdoor activities was positively associated with the self-reported PA levels (P ≤ 0.001).

CONCLUSIONS

To the best of our knowledge, this is the first study to report association between ACTN3 R577X genotype and PA level in middle-aged Scandinavians. Nevertheless, the contribution of a single polymorphism to a complex trait, like PA level, is likely small. Socioeconomic variables, as education and previous participation in sports or outdoor activities, are positively associated with the self-reported PA levels.

Renin-Angiotensin System Polymorphisms and Coronary Artery Surgery Patients

The frequencies of angiotensin-converting enzyme gene insertion/deletion, angiotensinogen-M253T, and angiotensin II type 1 receptor-A1166C polymorphisms were analyzed in 105 patients undergoing coronary artery bypass grafting (group 1) and a control group of 105 non-cardiac patients (group 2). Blood samples were obtained for biochemical analyses and DNA extraction. Genotyping was performed by polymerase-chain-reaction-based restriction analysis. According to the angiotensin-converting enzyme gene insertion/deletion polymorphism, 36.3% of patients in group 1 and 30.7% in group 2 were homozygous for the DD allele. This difference was not statistically significant. Angiotensin II type 1 receptor-A1166C genotype polymorphism was also not significantly different between the groups. The results showed the angiotensinogen-M235T polymorphism to be heterogenous. The MM homozygote frequency was significantly higher in controls (72.3%), whereas 80% of the TT homozygote frequency was in the surgical group ( p = 0.001). These results show that although there were no significant differences in angiotensin-converting enzyme gene insertion/deletion and angiotensin II type 1 receptor-A1166C genotype polymorphisms between the groups, angiotensinogen-M235T polymorphism of TT homozygote frequency was significantly associated with patients undergoing coronary artery bypass surgery.

Fast high-throughput screening of angiotensin-converting enzyme insertion/deletion polymorphism by variable programmed electric field strength-based microchip electrophoresis

An insertion (I)/deletion (D) polymorphism in angiotensin-converting enzyme (ACE) has been associated with susceptibility to various diseases in numerous studies. Traditionally, slab gel electrophoresis (SGE) after polymerase chain reaction (PCR) has been used to genotype this ACE I/D polymorphism. In this study, single- and multi-channel microchip electrophoresis (ME) methods based on variable programmed electric field strength (PEFS) (i.e., low constant, high constant, (+)/(-) staircase, and random electric field strengths) were developed for fast high-throughput screening of this specific polymorphism. The optimum PEFS conditions were set as 470V/cm for 0-9s, 129V/cm for 9-13s, 470V/cm for 13-13.9s, 294V/cm for 13.9-16s, and 470V/cm for 16-20s for single-channel ME, and 615V/cm for 0-22.5s, 231V/cm for 22.5-28.5s, and 615V/cm for 28.5-40s for multi-channel ME, respectively. In the multi-channel PEFS-ME, target ACE I/D polymorphism DNA fragments (D=190bp and I=490bp) were identified within 25s without loss of resolving power, which was ∼300 times faster than conventional SGE. In addition, PCR products of the ACE gene from human blood samples were detected after only 10 cycles by multi-channel PEFS-ME, but not by SGE. This parallel detection multichannel-based PEFS-ME method offers a powerful tool for fast high-throughput ACE I/D polymorphism screening with high sensitivity.

Frequency of APOE, MTHFR and ACE polymorphisms in the Zambian population

Background

Polymorphisms within the apolipoprotein-E (APOE), Methylenetetrahydrofolate reductase (MTHFR) and Angiotensin I-converting enzyme (ACE) genes has been associated with cardiovascular and cerebrovascular disorders, Alzheimer’s disease and other complex diseases in various populations. The aim of the study was to analyze the allelic and genotypic frequencies of APOE, MTHFR C677T and ACE I/D gene polymorphisms in the Zambian population.

Results

The allele frequencies of APOE polymorphism in the Zambian populations were 13.8%, 59.5% and 26.7% for the ε2, ε3 and ε4 alleles respectively. MTHFR C677T and ACE I/D allele frequencies were 8.6% and 13.8% for the T and D minor alleles respectively. The ε2ε2 genotype and TT genotype were absent in the Zambian population. The genetic distances between Zambian and other African and non-African major populations revealed an independent variability of these polymorphisms.

Conclusion

We found that the APOE ε3 allele and the I allele of the ACE were significantly high in our study population while there were low frequencies observed for the MTHFR 677 T and ACE D alleles. Our analysis of the APOE, MTHFR and ACE polymorphisms may provide valuable insight into the understanding of the disease risk in the Zambian population.

Angiotensin-converting enzyme insertion/deletion polymorphism and risk of myocardial infarction in an updated meta-analysis based on 34993 participants

The association between angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism and risk of myocardial infarction (MI) has been extensively studied. However, the results were in controversy. This study aimed to explore the association between ACE I/D polymorphism and risk of MI by using a meta-analysis. We retrieved the following databases to indentify eligible studies: Medline, Embase, ISI, VIP, CBM and Wan Fang database. The latest update was 10th May, 2012. Odds ratio and 95% confidence interval (95% CI) were used to present the strength of the association. A total of 40 case-control studies with 34993 participants were included. Overall, D allele of ACE I/D polymorphism was significantly associated with an increased risk of MI in genetic comparison models (OR (95% CI): 1.41 (1.22-1.64) for DD vs. II; 1.11 (1.01-1.21) for ID vs. II; 1.23 (1.10-1.37) for D carriers vs. II; 1.28 (1.15-1.43) for DD vs. I carriers and 1.06 (1.02-1.10) for D carriers vs. I carriers). Subgroup analyses, according to ethnicities and countries of participants also indicated that D allele was significantly associated with an increased risk of MI in Asians (especially for Chinese) and Caucasians (especially for English, French, Germans and Italians) (OR (95% CI) of DD vs. ID+II: 2.11 (1.65-2.70) for Asians and 1.15 (1.05-1.27) for Caucasians). In conclusion, this meta-analysis indicated that D allele of ACE I/D polymorphism was a possible risk factor for MI incidence for both Asians and Caucasians.

Do genetic variations alter the effects of exercise training on cardiovascular disease and can we identify the candidate variants now or in the future?

Cardiovascular disease (CVD) and CVD risk factors are highly heritable, and numerous lines of evidence indicate they have a strong genetic basis. While there is nothing known about the interactive effects of genetics and exercise training on CVD itself, there is at least some literature addressing their interactive effect on CVD risk factors. There is some evidence indicating that CVD risk factor responses to exercise training are also heritable and, thus, may have a genetic basis. While roughly 100 studies have reported significant effects of genetic variants on CVD risk factor responses to exercise training, no definitive conclusions can be generated at the present time, because of the lack of consistent and replicated results and the small sample sizes evident in most studies. There is some evidence supporting “possible” candidate genes that may affect these responses to exercise training: APO E and CETP for plasma lipoprotein-lipid profiles; eNOS, ACE, EDN1, and GNB3 for blood pressure; PPARG for type 2 diabetes phenotypes; and FTO and BAR genes for obesity-related phenotypes. However, while genotyping technologies and statistical methods are advancing rapidly, the primary limitation in this field is the need to generate what in terms of exercise intervention studies would be almost incomprehensible sample sizes. Most recent diabetes, obesity, and blood pressure genetic studies have utilized populations of 10,000–250,000 subjects, which result in the necessary statistical power to detect the magnitude of effects that would probably be expected for the impact of an individual gene on CVD risk factor responses to exercise training. Thus at this time it is difficult to see how this field will advance in the future to the point where robust, consistent, and replicated data are available to address these issues. However, the results of recent large-scale genomewide association studies for baseline CVD risk factors may drive future hypothesis-driven exercise training intervention studies in smaller populations addressing the impact of specific genetic variants on well-defined physiological phenotypes.

Association of genetic polymorphisms in the ACE, ApoE, and TGF beta genes with early onset ischemic heart disease

BACKGROUND

The genetic factors that contribute to ischemic heart disease (IHD) are poorly understood, and it is likely that multiple genes acting independently or synergistically contribute to the risk of IHD and outcome. The genes for angiotensin-converting enzyme (ACE) and apolipoprotein E (ApoE) have been implicated independently in the risk of IHD.

HYPOTHESIS

This study examined whether genetic polymorphisms in the ACE and ApoE genes are associated with early onset IHD. Polymorphisms in a third gene, transforming growth factor beta 2 (TGF beta 2), with a known role in wound repair and cardiac development, are also examined with respect to early onset IHD.

METHODS

In all, 101 patients with IHD and onset of disease before 55 years for men and 60 years for women, and 100 controls with angiographically confirmed normal coronary arteries were recruited for this study. The ACE, ApoE, and TGF beta 2 genotypes were determined by polymerase chain reaction amplification or Southern blotting and were compared with the patient's clinical and family histories.

RESULTS AND CONCLUSION

The frequency of the ACE D allele was significantly lower in the patient group (0.475) than in the control group (0.59, p = 0.03), which was attributed to a reduction in the number of patients with the DD genotype (patients: 24% DD, controls: 33% DD). Sudden cardiac death was also associated with the DD genotype. These data are consistent with the ACE D allele contributing to a fatal outcome. No association between the DD genotype and risk of myocardial infarction, presenting age, extent of vessel disease, family history, hypertension, or hypercholesterolemia was seen. Analysis of the ApoE genotype showed no association with early onset IHD. There was no evidence for a synergistic effect between the ACE and ApoE genotypes on the risk of early onset IHD. A polymorphism in the TGF beta 2 gene was rare and not associated with early onset IHD.

Quantitative phenotype analysis for localization and identification of disease-related genes in a complex genetic background

Results from genetic investigations of blood pressure and other variables in inbred rodent models are reviewed here to illustrate the power of quantitative approaches for the detection of linkage and the ultimate identification of the underlying genes. Different studies-involving angiotensinogen and hypertension, angiotensin I-converting enzyme and cardiovascular diseases, and other traits-are used to illustrate the possibility of similar approaches to multifactorial disorders in humans.

The association between angiotensin-converting enzyme gene polymorphism and coronary calcification. The Rotterdam Coronary Calcification Study

BACKGROUND

An insertion/deletion (I/D) polymorphism in the gene encoding angiotensin-converting enzyme (ACE) has been associated with serum ACE levels. The association between the ACE I/D polymorphism and coronary heart disease is unclear. Electron-beam-computed tomography (EBT) is a technique to non-invasively quantify the amount of coronary calcification. We investigated the association between the ACE I/D polymorphism and coronary calcification.

METHODS AND RESULTS

The Rotterdam Coronary Calcification Study is a population-based study in subjects aged 55 years and over. EBT scanning was performed in 2013 participants. Coronary calcification was quantified according to the Agatston score. The ACE I/D polymorphism was available for 1976 subjects. Geometric mean calcium scores in men with the II, ID and DD genotype were 167, 207 and 219, respectively. However, the difference in calcium score (p=0.19 for ID versus II; p=0.15 for DD versus II) and the trend (ptrend=0.17) were not significant. Calcium scores in women with the II, ID and DD genotype were 44, 42 and 36, respectively. There were no significant differences in calcium score (p=0.78 for ID versus II; p=0.29 for DD versus II), neither was the trend (ptrend=0.27). After we stratified on cardiovascular risk factors, no associations were present.

CONCLUSION

The present study failed to show an association between the ACE I/D polymorphism and coronary calcification in the general population. Also, no significant associations were present between the ACE I/D polymorphism and coronary calcification in strata of cardiovascular risk factors.

Association of the angiotensin-converting enzyme (ACE) gene G2350A dimorphism with essential hypertension

Although the angiotensin converting enzyme (ACE) is a strong candidate gene for hypertension, the extensively studied insertion-deletion dimorphism in intron 16 was not found to be associated with it. Several new polymorphisms in the ACE gene were identified, among which a dimorphism in exon 17, ACE G2350A, has a significant effect on plasma ACE concentrations. To assess the value of genotyping the ACE G2350A dimorphism in a genetically homogeneous population, we carried out a retrospective, case-control study of dimorphism G2350A for a putative association with essential hypertension (EH) in a Gulf population (Emirati)--an ethnic group characterized by no alcohol intake and no cigarette smoking. We investigated a sample population of 254 Emirati, comprising 136 normotensive controls, and 118 patients with clinical diagnoses of EH. ACE G2350A alleles were visualized by assays based on polymerase chain reaction and restriction endonuclease analysis. The ACE G2350A dimorphism showed an association with EH (chi2=6.71, 2 df, P=0.05). Further analysis revealed that the ACE G/G 2350 genotype was positively associated (OR=1.06-3.07, P=0.02) with EH. This is the first association study of the ACE G2350A dimorphism with EH, and the positive result might indicate that ACE could be a QTL for EH as originally thought.

Overestimation of genetic risks owing to small sample sizes in cardiovascular studies

We sought evidence of publication bias to explain conflicting findings in studies of angiotensin-converting enzyme deletion polymorphism (ACE D) and glycoprotein IIIa PlA2 (PLA2) polymorphism and the risk of myocardial infarction. Factor 5 Leiden (F5L), a well-established thrombotic risk factor, served as an internal comparison. We conducted systematic reviews of published studies involving ACE D, PLA2, F5L and relevant outcomes, searching medline (January 1990 through February, 2001), bibliographies, and meta-analyses. Random effects pooled odds ratios (95% confidence interval) for cardiovascular outcomes were as follows: PLA2 (n = 13,167 subjects): 1.13 (1.02, 1.26); ACE D (n = 42,140 subjects): 1.22 (1.11, 1.35); and F5L (n = 27,277 subjects): 4.43 (3.65, 5.38). However, funnel plots of ACE D and PLA2, but not F5L, showed an inverse relationship between sample size and odds ratios for ACE D (p = 0.02) and PLA2 (p = 0.04) but not F5L (p = 0.65) by Egger's test for potential publication bias. Despite research-based genotyping of over 50,000 subjects, the overall risk for myocardial infarction as a result of PLA2 and ACE D remains doubtful. Our study provides a clear example of how publication of underpowered studies can spuriously implicate polymorphisms as genetic risk factors.

Polymorphisms in the RAS and cardiac function

Since the discovery of the polymorphism in the angiotensin converting enzyme (ACE) and the consequences of this polymorphism on the activity levels of the enzyme, numerous association studies have been performed. However, these investigations do not often adhere to the most stringent criteria for such studies. The initial study reporting a positive association of the ACE polymorphism and myocardial infarction showed an increased risk of the DD genotype. This initial association was eventually refuted by a large, well conducted association study, which found a risk ratio of 1.02 after combining their own data with all published data. Although such large, well conducted association studies have not been performed in left ventricular (LV) hypertrophy, the association between DD genotype and hypertrophy is more convincing with a 192% excess risk of LV hypertrophy in untreated hypertensives. The role of ACE genotype in LV growth is well established, especially in athletes. In heart failure, large studies or meta-analyses have not been performed, because most studies have selected different end-points. This hampers a proper meta-analysis of the results obtained in associations with heart failure. As most association studies do not fulfill the criteria for good association studies and use too small sample sizes, it remains important to perform a meta-analysis to add meaning to the results of such studies. Above all, it is important to obey the rules set for association studies, large sample size, small P values, report associations that make biological sense and alleles that affect the gene product in a physiologically meaningful way.

Plasma total homocysteine levels and prognosis in patients with previous premature myocardial infarction: a 10-year follow-up study

OBJECTIVES

To explore plasma total homocysteine (tHcy) as a predictor of long-term prognosis after premature myocardial infarction (MI).

DESIGN

Prospective cohort study.

SETTINGS

Akershus University Hospital.

SUBJECTS

A total of 247 patients (193 men and 54 women) in stable clinical phase after premature MI (males: first MI at age < or =55; females < or =60).

MAIN OUTCOME MEASURES

The primary end-point was total mortality and the secondary end-point was cardiac death. The third end-point was major cardiac events: a combination of cardiac death, MI and cardiac arrest.

RESULTS

After 10 years, 44 patients had died, 36 from cardiac causes. Major cardiac event occurred in 70 patients. The relative risk for death of all causes increased 1.43 (95% CI, 1.08-1.88) per tHcy quartile (P for trend = 0.01), and was only modestly reduced after adjustment for age, ejection fraction, total cholesterol, C-reactive protein, fibrinogen, smoking and hypertension to 1.37 (95% CI, 1.04-1.80) (P for trend = 0.03). Similar results were observed when cardiac death was used as the end-point, but we observed no association between tHcy and the end-point major cardiac event.

CONCLUSIONS

Total homocysteine was an independent predictor of total and cardiac mortality in stable patients following premature MI. tHcy had no effect on major cardiac event in contrast to most other risk factors in this study. Thus, the mechanism(s) underlying the effects of homocysteine on coronary heart disease may differ from other risk factors.

Effects of oestrogen-only and oestrogen-progestogen replacement therapy upon circulating angiotensin I-converting enzyme activity in postmenopausal women

OBJECTIVE

Levels of angiotensin I-converting enzyme (ACE) in blood are associated with variation in cardiovascular disease risk. Serum ACE activity in women may be reduced by combined oestrogen-progestogen hormone replacement therapy (HRT). However, the relative contribution of each hormonal component to this observation is uncertain. We investigated ACE activity in two groups of healthy postmenopausal women receiving HRT regimens.

DESIGN

The first group received placebo or oestrogen-only HRT randomly (oral conjugated equine oestrogens or transdermal 17 beta-oestradiol). The second group was treated with oestrogen-only HRT (oral 17 beta-oestradiol) followed by sequential oestrogen-progestogen HRT (17 beta-oestradiol and dydrogesterone).

MEASUREMENTS

Assay of blood for soluble ACE activity before and whilst receiving HRT.

RESULTS

In the first group, oral conjugated equine oestrogens significantly reduced (P < 0.01) ACE activity by 18% on average relative to pretreatment whereas non-significant changes of -9% and +7% were seen with transdermal 17 beta-oestradiol or placebo treatment, respectively. In the second group oestrogen-only HRT significantly reduced (P < 0.001) ACE activity by 15% on average. The reduction during both the oestrogen-only and combined phases of sequential treatment was 12% and 19%, respectively, compared with pretreatment values (P < 0.01 and P < 0.001). ACE activity also differed significantly (P < 0.05) between the two phases of sequential treatment.

CONCLUSIONS

Both oestrogen-only and oestrogen-progestogen HRT may reduce ACE activity in blood. Oestrogen and progestogen may exhibit additive effects on blood ACE activity.

C-reactive protein predicts death in patients with previous premature myocardial infarction--a 10 year follow-up study

Atherosclerosis is an inflammatory disease. C-reactive protein (CRP), a marker of inflammation, is associated with coronary heart disease (CHD). We measured CRP in a cohort of 247 patients (193 males and 54 females) who had had their first myocardial infarction (MI) at age < or = 55 (males) or < or = 60 (females). The cut-off values of the 25th, 50th and 75th centiles of CRP were 1.20, 2.37 and 4.20 mg/l. After 10 years, a total of 44 patients (17.8%) had died, 36 (81.8%) of cardiac causes. Unadjusted and adjusted (i.e. for age, ejection fraction (EF), serum total cholesterol (TC), fibrinogen, smoking and hypertension) relative risks (RRs) for total and cardiac mortality were generated. CRP was a strong predictor of death of all causes due to its strength as predictor of cardiac death. The RR of cardiac death was doubled with increasing CRP quartiles, and patients in the top quartile had six times as high risk of cardiac death as patients in the lowest quartile. The RRs were moderately attenuated after adjustment, but still significant. We conclude that CRP is a strong predictor of mortality in patients with premature MI. Thus, inflammation appears to be a critical prognostic factor in patients with previous premature MI.

Aspects of gene polymorphisms in cardiovascular disease: the renin-angiotensin system

The renin-angiotensin system (RAS) plays a central role in cardiovascular homeostasis. Angiotensin is the key peptide of the RAS, and exerts its influence on the heart and blood vessels both through its haemodynamic effects (via its influence on after-load and pre-load and determining coronary vasoconstriction) and through its direct cellular effects (via its actions on cell proliferation). Numerous studies in the past 10 years have demonstrated that the pharmacological inhibition of angiotensin converting enzyme (ACE), one of the two critical enzymes of the RAS, improves the outcome in patients with several cardiovascular disorders (hypertension, heart failure, ischaemic heart disease). These studies suggest a role of the RAS as a major determinant of cardiovascular risk. Recent data suggest that genetics may in turn contribute to modulating the effects of angiotensin on coronary vascular biology and ischaemia. This paper reviews the physiologic characteristics of the RAS and recent research developments related to angiotensin cell biology and pathobiology in heart disease. In particular, this review will cover the genetic aspects of RAS and their implications in cardiovascular disease.

Genes of renin angiotensin system and coronary heart disease

Coronary constriction, proliferation of smooth muscle cells and arrhythmia are involved in the pathophysiology of coronary heart disease and its complications such as myocardial infarction and sudden death. All these effects are favoured by high angiotensin II levels. Angiotensin II is the main effector molecule of the renin angiotensin system and it acts through angiotensin II type receptors. Genetically determined differences in the expression of the components of this system could adversely affect angiotensin II concentration and subsequently heart. Consequently each component of this system represents a potential candidate in the etiology of cardiovascular disease. In this article we review the variation of the angiotensin I converting enzyme, angiotensin II type I receptor and angiotensinogen genes and their association with cardiovascular disease.

The DD-ACE genotype and cardiovascular disease

The renin-angiotensin-aldosterone system (RAS) plays a pivotal role in the cardiovascular system, and the therapeutic agents which interact with this pathway have a significant impact in both heart failure and following myocardial infarction (MI). Polymorphisms within the genes controlling this enzyme system may also contribute to the pathogenesis of cardiovascular disease. Over the last decade an association between a polymorphism of the angiotensin converting enzyme (ACE) gene (called the DD-ACE polymorphism) and phenotypic expression of cardiovascular disease, namely MI, has been reported. Since then, several small case-controlled studies have confirmed an association with manifestations of ischaemic heart disease or various other cardiac end points. However, in a large prospective study the ACE gene was found to confer no appreciable risk. This review article considers the evidence that links polymorphisms of the ACE gene with cardiovascular disease. The Medline database (1990 - 2000) was searched using the keywords myocardial infarction, ischaemic heart disease, angiotensin converting enzyme, polymorphisms (a search of the reference citations of relevant articles was also performed), and clinical studies on cardiovascular disease related to the ACE genotype were selected. Taken together, the available evidence supports the notion that the DD-ACE genotype adversely influences specific cardiovascular diseases, but appears to do so in specific geographical areas and in particular patient subgroups. It is not yet known whether it does this through an interaction with other genes or by as yet unexplained biochemical mechanisms. However, the impact of the DD-ACE genotype appears to be small and its clinical manifestations rather heterogeneous. This finding is not in contrast to the overall impact of the renin-angiotensin system in cardiovascular disease, given the fact that the ACE enzyme is only one component in the renin-angiotensin cascade and that one genetic variant cannot be expected to contribute more than a minor individual impact in genetically complex multifactorial cardiovascular disease.

Angiotensin-converting enzyme polymorphism and the risk of coronary heart disease in the Saudi male population

OBJECTIVE

To determine the relevance of angiotensin I-converting enzyme (ACE) gene polymorphism for coronary artery disease (CAD) in the Saudi population.

METHODS AND RESULTS

DNA of 84 male Saudi patients with established CAD, 36 male controls who underwent angiography, and 327 healthy Saudi male blood donors was amplified by polymerase chain reaction, using oligonucleotide primers flanking the insertion (I)/deletion (D) sites in the polymorphic region of intron 16 of the ACE gene. Polymerase chain reaction amplification resulted in 490-bp (II), 190-bp (DD), or 490- and 190-bp (ID) fragments. The genotype II distribution was 16.7% in the control group, 7.3% in the blood donor group, and 7.2% in the patients with CAD, and the distribution for DD was 58.3%, 47.1%, and 41.0%, respectively. Notably, 61.9% (P <.0001) of CAD patients presented with angina on admission, and 52.4% had diabetes mellitus.

CONCLUSIONS

The results show no increased risk of CAD in association with either the II or DD genotypes in the Saudi population. However, further investigation of genotype II as a predictor for atherosclerosis rather than increased risk of coronary heart disease may be indicated.

Large-scale test of hypothesised associations between the angiotensin-converting-enzyme insertion/deletion polymorphism and myocardial infarction in about 5000 cases and 6000 controls. International Studies of Infarct Survival (ISIS) Collaborators

BACKGROUND

The original report of a possible association between myocardial infarction and the insertion/deletion (I/D) polymorphism of the gene for the angiotensin-1-converting enzyme (ACE) indicated a risk ratio for myocardial infarction with the DD genotype of 1.34 (95% CI 1.05-1.70), and the association was claimed to be particularly strong in a retrospectively defined low-risk subgroup (3.2 [95% CI 1.7-5.9). Subsequent investigations reached varying conclusions, but all were small, and much larger studies were needed.

METHODS

4629 myocardial infarction cases and 5934 controls were compared. Cases were UK men aged 30-54 years and women aged 30-64 years recruited on presentation to hospital with confirmed myocardial infarction. Controls were aged 30-64 years with no history of cardiovascular disease, but were siblings or children of myocardial infarction survivors, or spouses of such relatives. All risk-ratio calculations allow for this relatedness of some of the controls. An updated meta-analysis of previous studies was also conducted.

FINDINGS

The ACE DD genotype was found in 1359 (29.4%) of the myocardial infarction cases and in 1637 (27.6%) of the controls (risk ratio 1.10 [95% CI 1.00-1.21]). The association between myocardial infarction and the DD genotype did not seem to be stronger in the subgroup defined as low risk by previously used criteria (234 [28%] of 836 cases and 911 [28%] of 3253 controls: risk ratio 1.04 [95% CI 0.87-1.24]), or in any other subgroup. Nor was the ACE I/D genotype predictive of subsequent survival.

INTERPRETATION

This study involved many more cases than any previously reported study of this question, but did not confirm the existence of any substantial association. In an updated meta-analysis of these results with those of previously published studies, the risk ratio for myocardial infarction with the DD genotype seems to lie in the range 1.0 to about 1.1. Although an increase in risk of up to about 10-15% cannot be ruled out, substantially more extreme risks can be. Moreover, there are not especially strong associations in the subgroups previously selected for emphasis. These findings illustrate the need for some studies of candidate genes to involve much larger populations than is customary, without undue emphasis on retrospectively defined subgroups.

Genetic risk factors and restenosis after percutaneous coronary interventions

Restenosis is the major limitation of percutaneous coronary interventions. Depending on the form of intervention and patients' characteristics, 20 to 50% of the treated patients incur significant restenosis. Restenosis is caused by a complex and only partially understood cascade of events. Thrombus formation at the injury site, formation of the neointima as a result of the migration and proliferation of smooth muscle cells (SMC) and extracellular matrix production, as well as constrictive remodeling of the vessel wall contribute by a variable degree to restenosis. Restenosis is not a random event but it affects selectively a certain subset of patients. These patients have some peculiar characteristics that help to identify the presence of a higher risk for restenosis. Conventional patient-related factors account only for a relatively small portion of the predictive power, much more contribution comes from lesion and procedural characteristics. There is increasing evidence that inherited factors may explain at least part of the excessive risk for restenosis observed in certain patients. Evidence exists that gene polymorphisms may lead to quantitative or functional alterations of the respective gene products. Recent studies have also found significant associations between several polymorphic alleles encoding for proteins with a relevant role in the process of lumen renarrowing and restenosis after percutaneous coronary interventions. The best studied polymorphisms in this regard are those of the genes encoding for angiotensin-converting enzyme and platelet glycoprotein-IIIa. Completed or ongoing studies have focused on polymorphisms of genes encoding for proteins interfering with lipid metabolism, hemostasis, nitric oxide production, inflammatory mechanisms, SMC proliferation and matrix production. The results of this research will have considerable pathophysiological and therapeutical implications for the battle against restenosis.

Angiotensin-converting enzyme and cardiovascular disease risk

The published studies of the association of the angiotensin-converting enzyme (ACE) genotype with cardiovascular disease have used many different diagnostic criteria for cardiovascular disease and have drawn their samples from different patient groups and different populations. This review examines the association of the ACE DD genotype with cardiovascular disease risk in studies grouped by their case criterion, the geographical region of the population samples, and by the cardiovascular risk level of the patient sample. In studies where the underlying odds ratios are determined to be homogeneous, the overall odds ratios for myocardial infarction and coronary artery disease with regard to the ACE DD genotype are estimated using the Mantel-Haenszel method.

Angiotensin I-converting enzyme and plasminogen activator inhibitor-1 gene variants: risk of mortality and fatal cardiovascular disease in an elderly population-based cohort

OBJECTIVES

We studied the contribution of putative risk genotypes at the angiotensin I-converting enzyme inhibitor (ACE D/D) and plasminogen activator inhibitor-1 (PAI-1 4G/4G) loci to all-cause and cardiovascular mortality in a population-based cohort.

BACKGROUND

The ACE D/D and PAI-1 4G/4G genotypes have been consistently associated with elevated plasma activities of the gene products. Their role in cardiovascular disease, although explored intensively, is still equivocal.

METHODS

The ACE and PAI-1 genotypes were determined in 648 subjects > or =85 years old. In a cross-sectional analysis, the genotype distributions in a subset of 356 elderly subjects who were born in Leiden, The Netherlands, were compared with those in 250 young subjects whose families originated from the same geographic region. In addition, the complete cohort of elderly subjects was followed over 10 years for all-cause and cardiovascular mortality and was stratified according to genotype.

RESULTS

In the cross-sectional analysis, the ACE and PAI-1 genotype distributions were similar in elderly and young subjects. In the prospective follow-up study, however, the age-adjusted risk of fatal ischemic heart disease was increased threefold (95% confidence interval [CI] 1.2 to 7.6) in elderly men carrying the PAI-1 4G/4G genotype. The risk of all-cause mortality was not increased among elderly subjects carrying the PAI-1 4G/4G (relative risk [RR] 0.9, 95% CI 0.7 to 1.1) or the ACE D/D genotype (RR 0.9, 95% CI 0.7 to 1.1), nor did we observe elevated risks of death from all cardiovascular diseases combined. There was no interaction between the genotypes.

CONCLUSIONS

The PAI 4G/4G genotype may be a risk factor for fatal ischemic heart disease in elderly men. The impact of moderately increased ACE and PAI-1 activities associated with the ACE D/D and PAI-1 4G/4G genotypes is too small to affect mortality in the general population.

Angiotensin I-converting enzyme gene polymorphism, coronary artery disease and myocardial infarction. An angiographically controlled study

OBJECTIVES

We investigated the association between insertion/deletion polymorphism of the angiotensin I-converting enzyme (ACE) gene, the presence and extent of coronary artery disease, and myocardial infarction.

BACKGROUND

The D allele of the ACE gene has been associated with coronary artery disease and myocardial infarction, but this association has been challenged in epidemiological studies.

METHODS

Nine hundred and sixty-nine men and 341 women undergoing coronary angiography were studied. The ACE genotypes were assessed by polymerase chain reaction from genomic deoxyribonucleic acid, homozygosity for the D allele was controlled using an insertion-specific primer. Coronary artery disease was defined by angiographic criteria, the extent of coronary artery disease by the number of coronary arteries with >/=50% lumen narrowing.

RESULTS

The ACE genotypes did not differ in terms of age, sex, body mass index, blood pressure, plasma lipids or lipoproteins. We found no association between the ACE genotypes and coronary artery disease (odds ratio, 95% confidence interval in DD genotypes for coronary artery disease in men 0.97, 0.70-1.36; in women 1.56, 0.95-2.57), extent of coronary artery disease (men 1.17, 0.85-1.61; women 1.24, 0.65-2.34), or myocardial infarction among the patients with coronary artery disease (men 1.07, 0.78-1.48; women 0.95, 0.50-1.76). The ACE genotype was not associated with coronary artery disease or myocardial infarction in hypertensives (n=771; odds ratio for coronary artery disease 0.93, 0.65-1.34; odds ratio for myocardial infarction 0.94, 0.66-1.33), or in patients </=60 years (n=649; odds ratio for coronary artery disease 1.05, 0.72-1.52; odds ratio for myocardial infarction 0.96, 0.63-1.47).

CONCLUSION

ACE insertion/deletion gene polymorphism is associated neither with the prevalence nor the extent of coronary artery disease, nor with myocardial infarction in this relatively large sample of Caucasian men and women. Genotyping for ACE insertion/deletion polymorphism is not useful in assessing the individual risk of coronary artery disease or myocardial infarction.

D allele of the angiotensin-converting enzyme gene is a risk factor for secondary cardiac events after myocardial infarction

We retrospectively examined the relationship between the genotype of the angiotensin-converting enzyme (ACE) gene or the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, and the secondary cardiac events after myocardial infarction. The study population consisted of 176 patients (ACE genotype: deletion homozygote (DD)=20, insertion/deletion heterozygote (ID)=91, insertion homozygote (II)=65; MTHFR genotype: valine homozygote (VV)=37, valine/alanine heterozygote (VA)=71, alanine homozygote (AA)=68) with acute or recent myocardial infarction at the start of the follow-up. We defined the occurrence of cardiac death, recurrent myocardial infarction, or admission due to unstable angina as the endpoint. Cardiac events related coronary intervention were excluded from the endpoints. During the follow-up (1903+/-1414 days), four patients had cardiac death, 12 patients had recurrent myocardial infarction and 13 patients had admission due to unstable angina. A Cox analysis revealed that the endpoints were significantly associated with diabetes mellitus (RR=4.423), total cholesterol level (RR=1.025) and the genotype of the ACE gene (RR=4.490). The ID or DD genotype of the ACE gene was associated with higher occurrence of the endopoints. The MTFHR gene was not associated with the endopoint. The present results suggest that the presence of the deletion allele of the ACE gene may be a risk factor for secondary cardiac events after myocardial infarction.

Angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists in the treatment of heart failure caused by left ventricular systolic dysfunction

Activation of the renin-angiotensin-aldosterone system (RAAS) in left ventricular systolic dysfunction is a critically important determinant in the pathophysiologic processes that lead to progression of heart failure and sudden death. Angiotensin II, acting at the specific angiotensin receptor (AT1-R), activates a series of intracellular signaling sequences which are ultimately expressed within the cardiovascular system as vasoconstriction and associated vascular hypertrophy and remodeling. Angiotensin converting enzyme (ACE) inhibition leads to increases in the vasodilatory peptides bradykinin and substance P and at least an initial reduction in angiotensin II concentrations. AT1-R blocking drugs prevent access of angiotensin II to the AT1-R and thus prevent cellular activation. ACE inhibitors have clearly been demonstrated through a large number of clinical trials to increase survival in congestive heart failure, primarily by reducing the rate of progression of left ventricular dilatation and decompensation. However, this beneficial effect diminishes over time. Preliminary short-term clinical studies evaluating the efficacy of AT1-R blocking drugs in the treatment of heart failure have suggested that they elicit similar hemodynamic and neuroendocrine effects as do the ACE inhibitors. The combination ACE inhibitors and AT1-R blocking drugs offer the theoretical advantage of increasing bradykinin while blocking the actions of angiotensin II, and thus possibly show a synergistic effect. Again, preliminary studies have yielded encouraging results that are difficult to interpret because neither ACE inhibitor nor the AT1-R blocking drug doses were titrated to tolerance. Pharmacological manipulation of the RAAS has led to better understanding of its role in heart failure and improved clinical outcomes.

Decrease with age in frequency of the homozygous deletional angiotensin-converting enzyme genotype in hypertensive patients

1. Angiotensin-converting enzyme (ACE) genotypes in hypertensive patients were studied in order to delineate their cardiovascular risk due to the ACE gene. We hypothesized that the distribution of ACE genotypes may change with age because of the risk of myocardial infarction associated with the homozygous deletional (DD) genotype. 2. A total of 223 subjects were recruited from the Hypertension Outpatient Clinic of the Sai Ying Pun Hospital with consent. They consisted of 75 patients with newly diagnosed or documented hypertension, 46 patients with ischaemic heart disease and 102 normal controls. Genomic DNA was extracted from peripheral leucocytes and amplified by polymerase chain reaction. Insertion (I) or deletion (D) alleles were identified after electrophoresis. The frequencies of ACE genotypes and alleles were measured in three age groups: < 50 years, 50-59 years and > or = 60 years. 3. A significant correlation between ACE genotype and age was found (P = 0.03). The relative frequency of the D allele in those under 50 years of age was similar in controls and hypertensive patients (0.40 vs 0.41; P = 0.94), but was significantly lower in patients > or = 50 years compared with those patients < 50 years of age (0.22 vs 0.41; P = 0.01). 4. The observed decrease in frequency of the DD genotype in older hypertensive patients is consistent with the increase in cardiovascular risk associated with the D allele and raises the possibility that the DD genotype may increase the risk of premature death, at least in the population studied.

ACE I/D gene polymorphism: presence of the ACE D allele increases the risk of coronary artery disease in younger individuals

BACKGROUND

Presence of the D allele or homozygosity for the deletion (D) allele of the ACE insertion/deletion (I/D) polymorphism has been discussed as potent risk factor for coronary artery disease (CAD) and myocardial infarction (MI).

METHODS AND RESULTS

In 2267 male Caucasians the relation of the ACE I/D gene polymorphism to CAD and MI were investigated. An association of the D allele to CAD was detected in younger subjects (e.g. < 61.7 years, mean value), but not in older patients (e.g. > or = 61.7 years). Additional exclusion of individuals with other cardiovascular risk factors (e.g. high BMI) produced an even stronger association of the D allele to CAD. In contrast, a relation of this polymorphism to non-fatal MI was only observed in older subjects; additional limitation to individuals without cardiovascular risk factors (e.g. BMI and/or diabetes) yielded a further enhancement of this association to MI. In younger subjects (e.g. < 61.7 years) the gene polymorphism was not related to non-fatal MI even after exclusion of additional risk factors.

CONCLUSIONS

The present large case-control study strengthens the assumption of an association of the ACE D allele with the risk of ischemic heart disease.

Insertion/deletion polymorphism in the angiotensin-converting enzyme gene is associated with atrial natriuretic peptide activity after exercise

An insertion/deletion polymorphism in the gene coding for the angiotensin-converting enzyme (ACE) is strongly associated with ACE activity. This polymorphism may be a marker for an increased risk for cardiovascular events. Our study examined a possible relationship between the D/I polymorphism and myocardial release of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Ninety-six individuals with normal or impaired left ventricular function were included in the study. ANP and BNP plasma levels were measured at rest and after exposure to physical stress. At rest no association of ACE genotypes with ANP and BNP was found. After exercise homozygotes with the genotype DD had significantly higher ANP plasma levels than homozygotes with the genotype II. In contrast to ANP, BNP levels were not significantly different between genotype groups after exercise. Differences in site of production and mode of release between ANP and BNP might explain this difference. We hypothesize that our result might represent a variability gene effect of the ACE gene locus on endocrine processes in the heart during exposure to physical stress.

Association of the missense Glu298Asp variant of the endothelial nitric oxide synthase gene with myocardial infarction

OBJECTIVES

We examined the possible association between the missense Glu298Asp variant of the endothelial nitric oxide synthase (eNOS) gene and myocardial infarction (MI).

BACKGROUND

Endothelium-derived nitric oxide (NO) plays a key role in the regulation of vascular tone. Recently, we reported that a missense Glu298Asp variant in exon 7 of the eNOS gene is a possible genetic factor involved in the pathogenesis of coronary spasm. Endothelium-derived NO also has vasoprotective effects by suppressing platelet aggregation, leukocyte adhesion and smooth muscle cell proliferation.

METHODS

We screened 285 patients with an MI and 607 control subjects in Kumamoto Prefecture, Japan. Genotypes were determined by polymerase chain reaction-restriction fragment-length polymorphism analysis.

RESULTS

The frequency of the missense Glu298Asp variant was significantly higher in the MI group than in the control group (21.1% vs. 13.3%, p = 0.003, odds ratio 1.73 for the dominant effect of the eNOS T allele). Multiple logistic regression analysis showed that the missense Glu298Asp variant was an independent risk factor for MI, as was diabetes mellitus, hypertension, cigarette smoking, hypercholesterolemia and body mass index.

CONCLUSIONS

There was a significant association of the missense Glu298Asp variant of the eNOS gene with MI. This marker-disease association may be due to the impaired effects of NO on the cardiovascular system: dysregulation of vascular tone, platelet aggregation and leukocyte adhesion and smooth muscle cell proliferation, all of which promote coronary atherosclerosis and thrombosis.

Angiotensin-converting enzyme gene polymorphism is not associated with coronary atherosclerosis and myocardial infarction in a sample of Italian patients

BACKGROUND

The deletion (D) allele of the angiotensin-converting enzyme (ACE) gene has been proposed as a genetic marker of the risk of ischaemic heart disease. However, the relationships between ACE genotypes, the development of coronary atherosclerosis and the occurrence of major coronary events are still controversial.

METHODS

To investigate whether the ACE I/D (insertion/deletion) polymorphism predicts the risk of coronary stenosis and myocardial infarction (MI), ACE genotypes were determined in 394 consecutive patients who underwent coronary angiography. The presence determined in 394 consecutive patients who underwent coronary angiography. The presence of coronary artery disease (CAD) (defined by > 50% stenosis) was detected in 236 patients (CAD+); 85 of these individuals had a history of MI. Patients with coronary stenosis < 10% (n = 158) served as controls (CAD-). ACE genotypes were determined by agarose gel sizing after polymerase chain reaction (PCR) amplification.

RESULTS

The distribution of ACE genotypes in CAD+ patients was not significantly different from that in CAD-patients (chi 2 = 2.63, P < 0.27). After controlling for other coronary risk factors, no significant increase in risk of CAD or MI was found to be associated with the D allele, regardless of whether the D allele was assumed to have a dominant, a codominant or a recessive effect. Similar results were observed in CAD+ patients at lower risk because of low body mass index and apolipoprotein B concentrations. Smoking, apolipoprotein B and history of hypertension were found to be independent predictors of CAD and MI.

CONCLUSION

Our study did not provide evidence of a significant association between ACE genotypes and the development of coronary atherosclerosis. It also failed to support a role of ACE I/D polymorphism in favouring the conversion of coronary stenosis to MI.

The deletion/insertion polymorphism of the angiotensin converting enzyme gene and cardiovascular-renal risk

OBJECTIVE

This meta-analysis attempted to derive pooled estimates for the associations between various cardiovascular-renal disorders and the deletion/insertion (D/I) polymorphism of the angiotensin converting enzyme (ACE) gene.

METHODS

Case-control studies were combined, using the Mantel-Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the within-study mean of the II genotype as the denominator.

RESULTS

The computerized database used for this analysis included 145 reports with an overall sample size of 49 959 subjects. Overall, possession of the D allele was associated with an increased risk of atherosclerotic and renal microvascular complications. In comparison with the II reference group, the excess risk in DD homozygotes (P < 0.001) was 32% for coronary heart disease (CHD; 30 studies), 45% for myocardial infarction (20 studies), 94% for stroke (five studies) and 56% for diabetic nephropathy (11 studies). The corresponding risk in DI heterozygotes amounted to 11% (P= 0.02), 13% (P= 0.02), 22% (P= 0.10) and 40% (P < 0.001), respectively. Hypertension (23 studies), left ventricular hypertrophy (five studies), hypertrophic or dilated cardiomyopathy (eight studies) and diabetic retinopathy (two studies) were not related to the DI polymorphism. Publication bias was observed for CHD, myocardial infarction and microvascular nephropathy, but not hypertension. In studies with DNA amplification in the presence of insertion-specific primers, the risk associated with the DD genotype increased to 150% [95% confidence interval (CI) 76-256; four studies] for diabetic nephropathy, but decreased to 12% (95% CI -3 to 28; seven studies) for CHD and 14% (95% CI -6 to 37; four studies) for myocardial infarction. On the other hand, the pooled odds ratios did not materially change if the meta-analysis was limited to articles published in journals with an impact factor of at least 4. Furthermore, compared with the II control group, the circulating ACE levels (29 studies) were raised 58 and 31% (P < 0.001) in DD and DI subjects, respectively. In contrast, plasma renin (10 studies), systolic and diastolic blood pressure (46 studies) and body mass index (30 studies) were not associated with the D allele.

CONCLUSION

The D allele is not associated with hypertension, but behaves as a marker of atherosclerotic cardiovascular complications and diabetic nephropathy. These associations do not necessarily imply a causal relationship and may have been inflated by publication bias. Nevertheless, their possible therapeutic implications may be subject to further investigation in prospective (intervention) studies.

Cardiovascular risk factors in people with different genotypes in the insertion/deletion (I/D) polymorphism at the locus for angiotensin I-converting enzyme (ACE)

The deletion (D) allele of an insertion/deletion (I/D) polymorphism at the locus for angiotensin I-converting enzyme (ACE) has been reported to be an independent risk factor for myocardial infarction (MI), particularly in people lacking traditional risk factors. Furthermore, a borderline association between Lp(a) lipoprotein level and the I/D polymorphism at the ACE locus was reported in one study. We have searched for possible "level gene" or "variability gene" effects of ACE genes on Lp(a) lipoprotein, total cholesterol (TC), high density lipoprotein (HDL) cholesterol (HDLC), low density lipoprotein (LDL) cholesterol (LDLC), triglycerides (TG), apolipoprotein B (apoB), apolipoprotein A-I (apoA-I), and body mass index (BMI). None of these variables differed significantly between genotypes in the I/D polymorphism in any of three population samples. A single population sample created by combining the three series, exhibited an insignificant trend towards individuals carrying the D-allele having a higher level of Lp(a) lipoprotein than those lacking it, and DD homozygotes had a significantly higher Lp(a) lipoprotein level than the combined group of ID/II individuals (p = 0.03). These results may indicate that the D-allele of the I/D polymorphism at the ACE locus could influence the level of Lp(a) lipoprotein.

Renin-angiotensin system: genes to bedside

Atherosclerosis and its vascular sequela are responsible for considerable morbidity and mortality rates. Several risk factors have been implicated in the pathogenesis of atherosclerosis, and the search for other risk factors continues on the medical horizon. Renin-angiotensin system (RAS), a multienzyme, multilocale axis, has been extensively studied as an important mediator of atherosclerosis. Recently, the tissue-based angiotensin system has been suggested as the most significant pathway of RAS. A genetic polymorphism in the human gene for the angiotensin-converting enzyme (ACE), one of the two enzymes of RAS, has been found to have a strong association with higher risk for acute coronary events, sudden cardiac death, vascular restenosis after angioplasty, and idiopathic and hypertrophic cardiomyopathy. Clinical and animal data support angiotensin II to be the final common pathway in the enzyme cascade of RAS and ACE as the key enzyme in the generation of Angiotensin II. ACE gene polymorphism appears to modify expression of cellular and free ACE levels and could represent a genetic marker for cardiovascular disease.

A DNA polymorphism at the angiotensin II type 1 receptor (AT1R) locus and myocardial infarction

Two hundred and thirty-five survivors of myocardial infarction (MI) were compared to 384 controls with respect to distribution of genotypes and gene frequencies in the A1166C polymorphism at the angiotensin II type 1 receptor (AT1R) locus. No differences in allele frequencies or genotype distribution were observed when all patients were compared with all controls. When comparing CC homozygotes with the combined group of CA heterozygotes and AA homozygotes (CA/AA), a difference in borderline significance between the MI group and controls was observed (p=0.05). In males alone, this difference was much more pronounced because of the larger proportion of males with the CC genotype in MI cases than in male controls (p=0.01). No significant differences were observed between female cases and controls. No interaction between the insertion/deletion (I/D) polymorphism at the angiotensin I-converting enzyme (ACE) locus and the polymorphism at the AT1R locus was detected. When subdividing the subjects into a "low-risk" and a "high-risk" group, based on levels of apolipoprotein B (apoB) and body mass index (BMI), and whether or not the person used lipid-lowering drugs, the frequency of CC homozygotes in male cases of the "low-risk" group differed significantly compared to the frequency in male controls of the "low-risk" group (p<0.001). No differences were observed in females, but the number of "low-risk" group female cases was low (n=3). Thus, CC homozygosity appears to be associated with MI in Norwegian males, especially among those with a "low-risk" phenotype.

Analyses of mutations in the human renal kallikrein (hKLK1) gene and their possible relevance to blood pressure regulation and risk of myocardial infarction

The kallikrein-kinin system is involved in the maintenance of blood pressure (BP), and studies have shown an inverse correlation between BP and urinary kallikrein levels. These and other effects, make the human tissue kallikrein (hKLK1) gene a candidate gene with respect to BP regulation as well as risk of myocardial infarction (MI). By analysis for single-stranded conformation polymorphisms (SSCPs), patterns consistent with four different variants of the gene were detected and further characterized by DNA sequencing. Three of the variants have not been described before. Two of the polymorphisms changed the codon for an amino acid. Methods based on the polymerase chain reaction (PCR) were developed to analyze these polymorphisms at the hKLK1 locus. We found no evidence of association between any genotype in the polymorphisms and normal BP level in two series of healthy, unrelated individuals. In a third series, diastolic BP exhibited a weak association with genotypes in three of the four polymorphisms. Since no such association was detected in the other two series, we conclude that no effect on normal BP level is exerted by variants in the hKLK1 as expressed in these polymorphisms. In two series of monozygotic (MZ) twin pairs, there were no differences between genotypes in within-pair difference in systolic BP or diastolic BP. Finally, no differences in allele frequencies or genotype frequencies in the four polymorphisms at the hKLK1 locus were found between a series of young MI survivors and a series of controls. Thus, genes in the four polymorphisms at the hKLK1 locus detected by SSCP and DNA sequencing did not exhibit associations with MI, and had neither "level gene" nor "variability gene" effects on normal blood pressure.

Associations between candidate loci angiotensin-converting enzyme and angiotensinogen with coronary heart disease and myocardial infarction: the NHLBI Family Heart Study

Angiotensin-converting enzyme (ACE) and angiotensinogen (AGT) are major components of the renin-angiotensin systems. An association between myocardial infarction (MI) and the ACE DD genotype of the insertion/deletion (ID) polymorphism in intron 16 of the ACE gene has been reported. However, other similarly designed studies have not found such an association. Angiotensin II, the product of AGT, has a direct effect on vascular tone; and a variant in the AGT gene has been found to be associated with MI in the Japanese. This case-control study was initiated to investigate whether the ACEI/D and AGT M235T polymorphisms are associated with an increased risk for coronary heart disease (CHD) and MI. Our study groups were composed of participants in the National Heart Lung Blood Institute (NHLBI) Family Heart Study (FHS) selected from three population-based studies: two Atherosclerosis Risk in Communities (ARIC) centers (Forsyth County, NC, and Minneapolis, MN), and the Framingham Heart Study. In multivariate analysis within ARIC Caucasians, a significant positive association was found between CHD (controls = 230, cases = 232) and the AGT TT genotype (P = 0.022; OR = 1.84, 1.09-3.10 95% CI). When we restricted the analysis to a low-risk group for CHD (controls = 70, cases = 35) an interaction between the ACE DD and AGT TT genotypes was significant (P = 0.025; OR = 5.02 1.22-20.6 95% CI). After further subsetting low-risk cases to those with a definite MI (controls = 74, cases = 16), we found that the associations with the ACE DD genotype was also significant (P = 0.013, OR = 3.94, 1.28-12.2 95% CI). Comparable tests in the Framingham sample failed to support an association of these markers with CHD. In conclusion, within selected groups the ACE D and AGT 235T alleles are statistically associated with CHD and MI, and there is a synergistic interaction between the two alleles. These results and those from previous studies together suggest that the association of these two loci is neither strong nor consistent and involves a complex interaction among risk factors and genotypes.

Lack of association of angiotensin I-converting enzyme gene polymorphism and premature myocardial infarction in Mauritian Indians

Eighty-five young Mauritian Indians, male survivors of premature myocardial infarction (MI) and thus belonging to a high risk group, were compared with 108 stringently selected controls for a possible association between premature MI and an insertion/deletion (I/D) polymorphism in the gene encoding angiotensin I-converting enzyme (ACE). The frequency of the D allele was 0.42 in the MI group and 0.43 in the control group, and thus no association between I/D polymorphism of ACE with susceptibility to early-onset MI was found in this population group. Other gene components of the renin-angiotensin system and lipid metabolism need to be explored to understand the genetic factors involved in causing MI at an early age.

Insertion/deletion polymorphism in the angiotensin-converting-enzyme gene and blood pressure during ergometry in normal males

A sample of 66 healthy, unrelated males with normal blood pressure were studied for a possible association between an insertion/deletion polymorphism in the gene coding for the angiotensin converting enzyme and blood pressure response to physical exercise. No association was found between the polymorphism and systolic blood pressure at rest and during stress. Statistically significant associations between the polymorphism and diastolic blood pressure were observed during exercise and post-stress. At maximal workload, among homozygotes for the deletion, the mean diastolic blood pressure was 93 (+/- 10) mmHg, among homozygotes for the insertion it was 82 (+/- 8) mmHg, among heterozygotes it was 85 (+/- 10) mmHg. The difference was still statistically significant 3 minutes post-stress. The angiotensin converting enzyme polymorphism may be a marker for genetically determined differences in the response of the cardiovascular system to physical stress.

Significance of angiotensin I-converting enzyme and angiotensin II type 1 receptor gene polymorphisms as risk factors for coronary heart disease

The D allele of an insertion/deletion (I/D) polymorphism in the angiotensin I-converting enzyme (ACE) gene is associated with a risk of myocardial infarction, and the relative risk associated with the ACE D allele is increased by the C allele of an angiotensin II type 1 receptor (AT1R) gene polymorphism (an A-->C transversion at nucleotide position 1166) [28]. The relation of the ACE and AT1R gene polymorphisms to coronary heart disease and the severity of coronary artery stenosis has now been investigated in 133 patients with myocardial infarction (MI) or angina pectoris who underwent coronary angiography and in 258 control subjects. The frequency of the ACE DD genotype as compared with non-DD was significantly higher in the patients who experienced an MI and in the low-risk patients than that in the controls (P < 0.05). The DD genotype showed a significantly increased risk of MI (odds ratio 1.85). The frequency of the AT1R A/C genotypes did not differ between the patients and the controls. The severity of coronary stenosis in the patients was estimated by the number of affected vessels (> 75% stenosis) and the coronary score of Gensini. Neither the number of affected vessels nor the coronary score differed among the ACE I/D genotypes. However, the number of affected vessels was significantly greater in patients with the AT1R AC genotype than in those with the 4A genotype (1.93 +/- 0.27 vs. 1.27 +/- 0.99; P < 0.05) (CC genotype was not found in the patients). After excluding patients with diabetes mellitus, the coronary score of those with the AC genotype was also significantly higher than in those with the AA genotype (51.7 +/- 34.4 vs. 18.2 +/- 23.3; P < 0.01). These results suggest that the ACE D allele is associated with the occurrence of myocardial infarction, while the AT1R C allele is involved in the development of the coronary artery stenosis.

Lack of association of angiotensin-converting enzyme (ACE). Gene insertion/deletion polymorphism with CAD in two Asian populations

Association of the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene with coronary artery disease with or without myocardial infarction (MI) was examined in a group of Chinese and Indian men in Singapore. The sample comprised an angiographically confirmed patient group of 276 Chinese and 102 Indians, of which 155 Chinese and 72 Indians had MI, and a matched healthy control group (147 Chinese and 166 Indians). The frequency of the D allele in the Chinese was 0.39 in those with CAD with MI, 0.43 in those with CAD but without MI, and 0.41 in the control group. The frequency of the D allele in Indians was 0.44 in CAD with or without MI, and 0.45 in the control group. There was no significant association of the ACE gene with CAD or MI in the Chinese or Indians, either in the entire sample or in different risk groups. The frequency of the D allele was significantly lower in the healthy Chinese and Indians than that reported in Caucasians. The association of the ACE gene with MI or CAD observed in other studies could not be confirmed in the present series of Chinese and Indians in Singapore.

Insertion/deletion polymorphism in the angiotensin-converting enzyme gene and risk of and prognosis after myocardial infarction

OBJECTIVES

We sought to prospectively investigate whether genetic variation at the angiotensin-converting enzyme gene locus defined by an insertion (I)/deletion (D) polymorphism influences the risk of myocardial infarction or prognosis after infarction, or both.

BACKGROUND

It has been suggested that the deletion allele of the angiotensin-converting enzyme gene, and specifically the DD genotype, may increase the risk of myocardial infarction, although previous studies have produced conflicting reports. No studies have yet examined the effect of I/D polymorphism on survival after infarction.

METHODS

Angiotensin-converting enzyme genotypes in 684 patients with myocardial infarction recruited at the time of the acute event through coronary care units in two centers were compared with those of 537 control subjects recruited from the base populations. All patients were followed up to assess the impact of the angiotensin-converting enzyme genotype on prognosis.

RESULTS

We found no difference (p = 0.89) in the genotype distribution between patients and control subjects (patients DD 31%, ID 47%, II 22%; control subjects DD 30%, ID 48%, II 22%). The odds ratio for myocardial infarction for DD compared with II/ID genotype adjusted for age, gender and center was 1.16 (95% confidence interval [CI] 0.82 to 1.65, p = 0.44). The study had 90% power to detect a 1.5-fold increase in risk of myocardial infarction associated with the DD genotype. For one center, data were available for other risk factors (hypertension, diabetes, angina, previous myocardial infarction, smoking, body mass index, total and high density lipoprotein cholesterol) in both patients and control subjects. In a stepwise logistic regression analysis the odds ratio for DD versus ID/II genotypes remained nonsignificant (1.44, 95% CI 0.84 to 2.46, p = 0.20) for these subjects. Over a median follow-up period of 15 months (range 3 to 22), 155 patients (22.7%) died. There was no difference in mortality between subjects with the DD genotype and those with ID/II genotypes. (21.8% vs. 23.1%, p = 0.25). Likewise, there was no difference in the distribution of survival times in the two groups (p = 0.62). The study had 70% power to detect a 1.5-fold increase in mortality during follow-up associated with the DD genotype.

CONCLUSIONS

We conclude that in the groups studied, genetic variation at the angiotensin-converting enzyme gene locus defined by I/D polymorphism does not significantly influence either the risk of or the short- to medium-term prognosis after myocardial infarction.

Aortic atherosclerosis in diabetes mellitus is associated with an insertion/deletion polymorphism in the angiotensin I-converting enzyme gene. No relation between the polymorphism and aortic collagen content

An insertion(I)/deletion(D) polymorphism in the angiotensin I-converting enzyme (ACE) gene seems to be associated with clinical heart disease in patients with diabetes mellitus. It is not known whether increased atherosclerosis or other factors among individuals with certain ACE-gene subtypes form the basis for the increased prevalence of heart disease among these subjects. We measured, at autopsy, the extent of macroscopically visible aortic atherosclerosis in 22 diabetic and 39 non-diabetic subjects and determined the ACE-genotype of all individuals by the polymerase chain reaction. The percentage of aortic surface area covered with atherosclerotic lesions was 29 +/- 8 (n = 6), 71 +/- 7 (n = 9), and 65 +/- 7 (n = 5) in the II-, ID-, and DD-genotype subgroups, respectively, among diabetes patients (mean +/- SEM) (2 p < 0.01, when comparing values from the ID and DD groups to the II group). The values were 37 +/- 9 (n = 11), 40 +/- 5 (n = 14) and 37 +/- 6 (n = 11) in the II-, ID-, and DD-genotypes in the non-diabetic group. There were no differences in sex ratio or age in any of the ACE-gene subtypes. The previously described relationship between heart disease and the ACE-gene polymorphism in diabetes could thus be founded in an increased extent of atherosclerosis among patients with the ID- and DD-ACE-gene subtypes. Patients with diabetes have several alterations in the composition of the collagenous components in the arterial wall. We also analysed for associations between total collagen and type IV and type V collagen content in the aortic vessel wall and the ACE-gene subtypes. We were, however, not able to disclose correlations between the polymorphism and any of these parameters. In conclusion, our data show an association between the ACE-I/D polymorphism and the degree of aortic atherosclerosis in diabetes; however, we did not observe correlations between the polymorphism and data concerning arterial collagenous components.

Angiotensin converting enzyme as a genetic risk factor for coronary artery spasm. Implication in the pathogenesis of myocardial infarction

It has been reported that individuals with the D allele of an insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene are at greater risk for myocardial infarction (MI), especially among subjects normally considered to be at low risk. However, little is known about the mechanism by which the ACE polymorphism affects the risk of MI. Coronary artery spasm (CAS) is considered to be one possible mechanism for developing MI. We therefore examined the ACE polymorphism relation to CAS to determine if this was the mechanism by which the DD genotype influences MI. We studied 150 angiographically assessed Japanese males, all more than 60 yr old. CASs were detected using intracoronary injection of ergonovine maleate. Subjects were divided into three groups: those with CAS (group 1), those without CAS, but with fixed organic stenosis (group 2); and those without CAS and no organic stenosis (group 3). DD subjects were significantly represented in group 1 when compared with groups 2 (P = 0.002) and 3 (P = 0.026). These results suggest that the DD genotype relates to the greater risk for MI in the patients with CAS.

Vascular wall thickness in hypertension: the Perindopril Regression of Vascular Thickening European Community Trial: PROTECT

A high prevalence of increased intima/media thickness of the arterial wall has been documented in hypertension. These alterations in vascular wall structure may be potent determinants for the promotion of the development of atherosclerosis. Direct histologic data from animal models of hypertension, and indirect data from hypertensive patients, have demonstrated a marked regression of increased intima/media thickness by angiotensin-converting enzyme (ACE) inhibition. Long-term effects of ACE inhibition on structural wall changes in humans have not been examined. Therefore, a multicenter, randomized, double-blind European trial was designed to compare the effects of the ACE inhibitor perindopril and the diuretic hydrochlorothiazide in slowing or reversing progression of increased intima/media thickness of carotid and femoral arteries in hypertensive patients. A total of 800 patients at 17 clinical centers in 7 European countries, aged 35-65 years, with hypertension and ultrasonographically proven intima/media thickness > or = 0.8 mm of the common carotid artery will be randomly assigned to receive in a double-blind fashion either perindopril or hydrochlorothiazide and will be followed for 24 months. High resolution duplex sonography will be used to quantify intima/media thickness at baseline and twice a year during follow-up. A change of 0.1 mm of intima/media thickness from baseline is considered to be detectable, and the standard deviations of the changes from baseline are expected not to be higher than 0.2 mm. The primary endpoint of the study is the comparison of changes in intima/media thickness of the common carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)