An angiotensin-converting enzyme gene variant is associated with acute myocardial infarction in women but not in men

Association between ACE and AGT polymorphism and cardiovascular risk in acromegalic patients

PURPOSE

Whether the renin-angiotensin-aldosterone system plays a role or not in the development of cardiovascular morbidity in acromegaly patients is unknown. The aim of the study was to investigate the association between ACE (I/D) and AGT (M235T) gene polymorphisms and cardiovascular and metabolic disorders in the acromegaly.

METHODS

The study included one hundred and seventeen acromegalic patients (62 F/55 M, age: 50.2 ± 12.3 years) and 106 healthy controls (92 F/14 M, age: 41.4 ± 11.3 years). PCR method was used to evaluate the prevalence of ACE and AGT genotype.

RESULTS

The genotypes of ACE polymorphism in acromegalic patients were distributed as follows; 41.0% (n: 48) for DD, 44.4% (n: 52) for ID and 14.5% (n: 17) for II genotype. The control group had significantly different distribution of the ACE polymorphism [48.1% (n: 51) for DD, 25.5% (n: 27) for ID and 26.4% (n: 28) for II genotype]compared to acromegalic group. Regarding AGT polymorphism, AGT-MT genotype was seen in 88.9% of the acromegalic patients while MM and TT genotype (9.4% and 1.7%, respectively) were present in the rest. The controls had similar distribution of the AGT genotype with the acromegaly group (80.2% MT genotype, 15.1% MM genotype and 4.7% TT genotype). Due to the small number of patients with TT allele (n: 2), T carriers for AGT genotype (AGT-MT+TT) were subgrouped and compared to those with AGT-MM group. ACE-DD, ID and II groups had similar anthropometric measures, blood pressure values and baseline GH and IGF-1 levels. Significantly higher baseline GH levels were found in AGT-MM group compared to T allele carriers [40 (16-60) vs. 12 (5-36) µg/L, p < 0.05]. The compared groups in both polymorphisms had similar fasting plasma glucose levels. Patients with ACE-II genotype had significantly higher HDL-C levels compared to those with ACE-DD and ACE-ID polymorphisms (p < 0.05) whereas there was no significant difference in lipid profile between AGT-MM group and AGT-T allele carriers. Moreover, the compared groups in both polymorphisms had similar distribution of hyperlipidemia, hypertension, impaired glucose metabolism (prediabetes or type 2 diabetes mellitus) and coronary artery disease. In terms of echocardiographic parameters, systolic and diastolic function was similar among the groups in ACE and AGT genotypes. Interestingly, AGT-MM group had higher mitral inflow A_peak values than T allele carriers (0.94 ± 0.46 vs. 0.73 ± 0.20; p = 0.051). No significant difference was observed in LV mass index values in acromegalic patients among the groups in both polymorphisms.

CONCLUSIONS

Both ACE (I/D) and AGT (M235T) gene polymorphisms do not seem to have a significant effect on the development of clinical properties or cardiovascular comordities of acromegalic patients.

Sex Difference in the Effect of ACE-DD Genotype on the Risk of Premature Myocardial Infarction

In this association study the authors compared the insertion/deletion (I/D) angiotensin-I converting enzyme (ACE) gene polymorphism in females and males with premature myocardial infarction (MI). I/D ACE gene polymorphism was tested in 738 subjects: 302 patients with MI (151 men and 151 women) and 436 healthy subjects (207 men and 229 women). In women the ACE-DD genotype was not associated with MI (OR 1.1, 95% CI 0.6-2.1, p=0.6), whereas the ACE-DD genotype conferred a 2-fold independent risk for MI in men (95% CI=1.2-3.4; p=0.013) after adjustment for cardiovascular risk factors. The authors found evidence for the sex difference in the effect of the ACE-DD genotype on MI risk. The ACE-DD genotype conferred a 2-fold independent risk for premature MI in males.

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.

Angiotensin converting enzyme I/D, angiotensinogen M235T and AT1-R A/C1166 gene polymorphisms in patients with acromegaly

Acromegaly is associated with increased morbidity and mortality related to cardiovascular disease. Hypertension is one of the most common cardiovascular risk factors in acromegalic patients. The aim of this study was to investigate association between the frequencies of angiotensin converting enzyme (ACE) I/D, angiotensinogen (AGT) M235T and the angiotensin II type 1 receptor (AT1-R) A/C1166 gene polymorphisms and some clinical parameters of acromegalic patients. Total of 33 acromegalic patients and 63 controls were enrolled to study. We determined the ACE I/D, AGT M235T and AT1-R A/C1166 gene polymorphisms. Serum insulin, glucose, triglyceride, HDL-cholesterol, LDL-cholesterol, growth hormone and Insulin-like growth factor I (IGF-I) levels of subjects were analyzed. The frequencies of ACE and M235T AGT genotype were not significantly different between control and patients. The distribution of AT1R A/C1166 genotypes was significantly different between patients and control subjects (P=0.016). None of the three ACE genotypes, DD, ID and II displayed significant difference in acromegalic patients. A significant difference in systolic blood pressure and the serum IGF-I levels among the three AGT genotype, MM, MT and TT genotypes was found in patient group. Individuals with MT genotypes had significantly higher serum IGF-I levels and systolic blood pressure than MM and TT genotype subjects, P<0.05. In addition, serum triglyceride and HDL levels differed significantly between MM and MT genotypes, P<0.05. However, systolic blood pressure of patients with CC genotypes was found to be significantly higher than AA genotypes individuals in acromegaly group, P<0.05. It can be said that the angiotensinogen MT and AT1R CC1166 genotype carriers may have more risk than other genotypes in the development of hypertension in acromegaly.

Association of angiotensin-converting enzyme gene 2350G>A polymorphism with myocardial infarction in a Chinese population

Angiotensin-converting enzyme (ACE) gene 2350G>A polymorphism has the most significant effect on plasma ACE concentrations. But the association between this polymorphism and myocardial infarction (MI) is presently unknown. We carried out a case-control study in the Chinese Han population. ACE2350G>A genotypes of 231 patients with MI and 288 healthy controls were detected by PCR-RFLP. Differences in frequencies of ACE genotypes and alleles and their associations with clinical features were assessed. The distribution of the ACE2350G>A genotypes (GG, GA, and AA) was 20.78%, 51.08%, and 28.14% in the MI group and 31.60%, 46.53%, and 21.87% in controls, respectively (P = .0167).The frequency of the A allele in the MI group was significantly higher than that in controls (53.68% vs 45.14%, P = .0062). The A allele carriers (GA + AA genotypes) had approximately 2-fold increased risk of MI when compared with the GG genotype (odds ratio = 1.76; 95% confidence interval = 1.24-3.52). There were no significant differences among the 3 genotypes in plasma levels of lipids, apolipoproteins, high-sensitivity C-reactive protein, and soluble CD40 ligand in either the MI group or the control group (P > .05). No statistical difference was observed between ACE2350G>A polymorphism and severity of the coronary lesions (P > .05). These results suggest that ACE2350G>A polymorphism is associated with acute MI, and A allele carrier is an independent risk factor for acute MI in the Chinese Han population.

A novel genetic marker for coronary spasm in women from a genome-wide single nucleotide polymorphism analysis

OBJECTIVE

Coronary spasm plays an important role in the pathogenesis of variant angina and also ischemic heart diseases in general, and it is more likely to occur in angiographically normal coronary arteries than in stenotic coronary arteries. We previously found a -786T/C polymorphism in the 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene and reported that this polymorphism is associated with coronary spasm. We report on an investigation of the genetic factor(s) associated with coronary spasm utilizing a genome-wide case-control study.

METHODS AND RESULTS

We recruited 411 consecutive Japanese women (201 with coronary spasm; 210 controls) who were all underwent an acetylcholine provocation test. For single nucleotide polymorphism analysis (SNP), 116,204 SNPs were genotyped for 100 women (50 with coronary spasm; 50 controls) utilizing the Affymetrix GeneChip 100 K Set. Case-control studies were performed with 311 women (151 with coronary spasm; 160 controls) using the 10 lowest permutation P value SNPs from the initial SNP analysis. Finally, we discovered SNP rs10498345, a genetic marker for coronary spasm in Japanese women (Odds ratio=0.43, P=9.48x10(-7)). Haplotype analysis showed that haplotype H2, the only haplotype containing the protective A allele at SNP rs10498345, was most strongly associated with coronary spasm (permutation P value <1x10(-4)). SNP rs10498345 was strongly associated with the vasoconstrictor response to acetylcholine. Northern blot analysis revealed a novel 4.7 kb RNA transcript, which lacked poly (A), nearby SNP rs10498345.

CONCLUSIONS

SNP rs10498345 was strongly associated with coronary spasm in Japanese women utilizing genome-wide SNP analysis.

ACE-DD genotype is associated with the occurrence of acute coronary syndrome in postmenopausal women

The insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE), the A1166C polymorphism in the angiotensin type 1 receptor (AT1R), and the M235T polymorphism of the angiotensinogen gene are associated with cardiovascular disease mostly in men. Few data are available on the effects of these genetic variations in postmenopausal women according to hormone replacement therapy (HRT) use. In this case-control study, we determine the frequency of mutant alleles in the ACE I/D, M235T and A1166C polymorphisms in postmenopausal Caucasian women with and without a diagnosis of acute coronary syndrome (ACS). Data from 198 women with ACS (63+/-10 years) and 149 controls (62+/-7 years) showed that ACE-DD genotype was more prevalent in women with ACS compared to controls (30% vs. 19%, P<0.05). There was no difference in genotype distributions for either the M235T or the A1166C polymorphisms between groups. The difference in ACE genotype distribution between ACS women and controls was driven by current HRT users with 30% of ACS and 15% of controls carrying the ACE-DD genotype (P<0.05). The oligenic combination of ACE-DD and M235T-TT genotypes was higher in ACS compared to controls. Among carriers of M235T-TT, 7% of ACS and 1% of controls also had the ACE-DD genotype, P<0.05. Thus, the ACE-DD genotype may be associated with ACS in postmenopausal women, particularly in HRT users.

The paradoxical association of common polymorphisms of the renin-angiotensin system genes with risk of myocardial infarction

BACKGROUND

The insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) and the A1166C polymorphism of the angiotensin-II AT1 receptor (AT1R) have been extensively investigated as possible risk factors for myocardial infarction (MI).

DESIGN AND METHODS

Genetic association, case-control study, specifically designed to investigate the association of the above-mentioned polymorphisms with risk of MI in a homogeneous, low coronary risk, Caucasian population. The study population consisted of 1603 consecutive patients with acute MI who were recruited from nine clinics, located in three cities, and 699 unrelated adults who were randomly selected from the city catalogues.

RESULTS

In univariate analysis, the DD genotype was found to be more prevalent among controls (40.8 vs. 35.2%, P=0.011). In multivariate analysis adjusted for age, gender, smoking status, diabetes mellitus, hypercholesterolaemia, hypertension and family history of coronary artery disease, the presence of the DD genotype was independently and negatively associated with risk of AMI (RR=0.743, 95% CI=0.595-0.927, P=0.008). The CC genotype was not found to be significantly associated with risk of MI, either in univariate (6.2 vs. 6.4%, P=0.856), or in multivariate analysis adjusted for the same confounders (RR=0.743, 95% CI=0.473-1.167, P=0.197).

CONCLUSIONS

Contrary to previous reports, in this study the DD genotype of the ACE gene, but not the CC genotype of the AT1R gene, was associated with a lower risk of MI. Our results emphasize the complexity of genotype-phenotype interactions in the pathogenesis of ischaemic heart disease and question the previously hypothesized role of the DD genotype on risk of acute myocardial infarction.

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.

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.

Relationship of venous thromboembolism and myocardial infarction with the renin-angiotensin system in African-Americans

Genetic polymorphisms/mutations associated with venous thrombosis have largely been confined to the genes that encode for proteins in either the coagulant or the anticoagulant pathway. Although genetic alterations in the renin-angiotensin system have been reported to have a role in myocardial infarction and hypertension, there is recent evidence to suggest that there may also be an association with venous thrombosis. To extend our earlier observation of an association between the ACE DD genotype in African-American males and venous thrombosis, other genes in the renin-angiotensin pathway were investigated for possible disease association and were compared with African-Americans with myocardial infarction. African-American patients with a documented history of venous thrombosis or a history of myocardial infarction were eligible for participation as cases in the study. Control subjects were African-American outpatients attending a clinical laboratory for routine blood tests who had comparable age and gender distributions to the cases. Persons with a history of myocardial infarction, stroke, or thrombosis were excluded. Genes that were analyzed for known polymorphisms included angiotensinogen, angiotensin-converting enzyme (ACE), and the angiotensin II type I receptor. Our results showed that the ACE DD genotype was also associated with MI in African-American males but not in females. Racial/ethnic and sex differences were also found with respect to the genotype distribution of the ACE 4656(CT)(2/3) polymorphism. It was observed that the 2/2 genotype had a protective effective in males for myocardial infarction and venous thrombosis. The data also demonstrated that the allele frequencies of the A1166C variant of the angiotensin II type I receptor were different in African-Americans as compared to Caucasians.

Is angiotensin I-converting enzyme a "master" disease gene?

Clustering of diseases has been appreciated by health insurers and epidemiologists for some time. Co-morbidity suggests shared pathways of disease. It is by now well agreed that common diseases have a strong genetic component. Here we present evidence that the angiotensin I-converting enzyme (ACE) deletion/deletion (D/D) genotype is associated with a large number of common adult diseases, including cardiovascular disease, cancer, and psychiatric disease. Since the ACE D/D genotype has been shown to be associated with increased levels of tissue ACE expression at the protein level, these data suggest that overactivity of ACE may be involved in the pathogenesis of common diseases, as well as the utility of effective ACE inhibition in their treatment and, perhaps, prevention.

Angiotensin II type-I receptor and ACE polymorphisms and risk of myocardial infarction in men and women

BACKGROUND

Findings relating an association between an insertion/deletion polymorphism of the angiotensin converting enzyme (ACE) gene and myocardial infarction (MI) have been mixed. While other loci, such as the angiotensin II type-I receptor (AT1R), may modulate risk, few studies have adequately documented the risk in women. We aimed to study whether the findings in respect of ACE and AT1R in UK men were borne out in women.

METHODS

Cases of MI (305 women, 391 men) in Belfast and Glasgow have been compared to controls (291 women, 356 men). These new samples augment the original men (200 cases, 181 controls) included from Belfast in the ECTIM study.

RESULTS

Among men, the odds ratio for MI for ACE (DD vs. ID + II) was 1.03 (0.79, 1.34) and among women, 0.69 (0.47, 1.01). This heterogeneity between the risks in men and women was significant in Glasgow (P = 0.02). Among men and women the odds ratio for MI for AT1R (CC vs. AC + AA) was 1.02 (0.71, 1.47). There was a small gradient in risk, such that the odds ratio for DD genotype was 0.86 (0.63, 1.17) among subjects homozygous for the common AT1R allele (AA): 0.94 (0.67, 1.30) among heterozygotes and 1.21 (0.53, 2.77) among CC subjects; but this interaction was not statistically significant.

CONCLUSIONS

Some of the contradictory findings concerning the ACE polymorphism and the risk of MI may be due to heterogeneity in the risk between men and women. The AT1R1196 polymorphism is not an independent risk factor for MI in either sex.

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.

ACE gene polymorphism in cardiovascular disease: meta-analyses of small and large studies in whites

The objective of this study was to assess the influence of the ACE gene insertion (I)/deletion (D) polymorphism on plasma ACE activity; blood pressure; and risk of myocardial infarction, ischemic heart disease, and ischemic cerebrovascular disease by comparing small and large studies. The meta-analyses are based on a literature search of MEDLINE up until April 1998 and assessment of bibliographies of published studies and reviews. Forty-six studies were selected, including a total of 32 715 white individuals. Plasma ACE activity was increased 40% and 71% for ID and DD versus II in small studies and 21% and 48% in large studies (small versus large: P<0.001 and P<0.001). Blood pressure was not influenced by genotype. Risk of myocardial infarction and ischemic heart disease was increased by 47% and 29%, respectively, for DD versus ID and II genotypes in small studies but not in large studies (small versus large: P<0.001 for risk of myocardial infarction and P=0.01 for risk of ischemic heart disease). Risk of ischemic cerebrovascular disease was not increased either in the small or in the largest study. In conclusion, the ACE gene polymorphism affects plasma ACE activity but not blood pressure and is not associated with increased risk of myocardial infarction, ischemic heart disease, or ischemic cerebrovascular disease in the largest studies.

Carotid intima-media thickness and coronary heart disease risk factors in a low-risk population

OBJECTIVE

Coronary heart disease (CHD) risk factors have been consistently related to an increase in carotid intima-media thickness (IMT) in selected populations. However, few studies were population-based and furthermore little attention has been given to the influence of CHD risk factors on IMT in low-risk populations for CHD.

DESIGN

We examined the association between carotid IMT and CHD risk factors in a large (n = 1013) and representative sample of middle-aged men and women in one of the European populations with the lowest CHD risk.

METHODS

High-resolution B-mode ultrasonography of the common carotid arteries was performed.

RESULTS

Age, smoking (not significant in women), body mass index, waist to hip ratio, systolic (SBP) and diastolic blood pressure, alcohol consumption, total and low-density lipoprotein cholesterol, triglycerides, glycaemia, fibrinogen (not significant in women), haematocrit (not significant in men) and insulin (not significant in women) were positively and significantly associated with mean IMT. High-density lipoprotein (HDL) cholesterol (not significant in women) was negatively and significantly associated with mean IMT. In a subsample of 355 men, IMT was not associated with angiotensin I-converting enzyme gene polymorphism. Multivariate analyses showed, in men, independent associations between mean IMT (0.61+/-0.11 mm) and age, pack-years, SBP, HDL cholesterol, alcohol and the interaction between age and alcohol. In women, only age and SBP were independently associated with mean IMT (0.58+/-0.09 mm).

CONCLUSIONS

We found thinner IMT than those found in high-risk populations, suggesting that an increased IMT might reflect local atherosclerosis. Protective factors such as HDL cholesterol or regular and moderate alcohol consumption are probably important determinants of the early stages of atherosclerosis in these low-risk populations.

Chymase gene locus is not associated with myocardial infarction and is not linked to heart size or blood pressure

The chymase gene is said to be important for the generation of angiotensin II in the heart and therefore is a candidate gene for heart disease. However, we were unable to find an association between allelic variants of the chymase gene and acute myocardial infarction or linkage between the chymase gene locus and heart size.

Various actions of oestrogens on the vascular system

Epidemiological studies show a reduction in cardiovascular disease with postmenopausal oestrogen use. Oestrogens have been shown to have both metabolic effects and direct effects on the vasculature, both of which may improve arterial function and reduce or reverse atheroma formation. The metabolic effects include changes in lipids and lipoproteins, glucose and insulin metabolism, coagulation and fibrinolysis. The direct arterial effects include changes in endothelium-dependent processes, ion channels, renin-angiotensin system and remodelling processes. The various actions of oestrogens on the vascular system are reviewed. It is clearly important to understand the biological basis of these effects of oestrogen on the cardiovascular system in order to optimize current and future hormone-replacement therapy in women after natural or surgical menopause.

Angiotensin-converting enzyme genotypes and risk for myocardial infarction in women

OBJECTIVES

We tested for an association between the angiotensin-converting enzyme (ACE) DD polymorphic genotype and myocardial infarction (MI) in a sample group composed exclusively of women.

BACKGROUND

The human ACE gene occurs with either an insertion (I allele) or a deletion (D allele) of a 287-base pair (bp) Alu element. Part of the variance in serum ACE levels may be accounted for by this polymorphism. Also, the DD genotype has been associated with an increased risk of MI in predominantly male populations. However, the risk in women is poorly defined.

METHODS

Genomic DNA was extracted from buffy coat blood using a phenol/chloroform method. Angiotensin-converting enzyme alleles were identified using primers to bracket the insertion region in intron 16. Amplification using polymerase chain reaction allowed identification of a 490-bp (I allele) or a 190-bp (D allele) product, or both.

RESULTS

Allelic and genotypic frequencies in control subjects were similar to those reported in mostly male populations, and frequencies of genotypes were in the Hardy-Weinberg equilibrium. In contrast, the distribution of genotypes in patients with MI diverged from the equilibrium. Specifically, DD genotypic frequency was increased in women with (n = 141) versus without (n = 338) a previous MI (39% vs. 29%, odds ratio [OR] 1.54, 95% confidence interval 1.02 to 2.32, p < 0.04). Risk was particularly increased in women <60 years old (OR 2.04, p < 0.05). In contrast, the DD genotype did not predict angiographic coronary artery disease.

CONCLUSIONS

Consistent with findings in male-dominated populations, a modest association of the ACE DD genotype with MI was found in women. The basis for this association requires further study.

Angiotensin I-converting enzyme genotype influences arterial response to injury in normotensive rats

Two normotensive strains of rat, the Lou and Brown Norway (BN) strains, have contrasting levels of plasma angiotensin-converting enzyme (ACE). To investigate the degree of genetic determination of ACE expression, a polymorphic marker of the ACE gene was analyzed in inbred rats of the two strains. The two inbred strains were shown to bear different alleles for a polymorphic marker at the ACE gene. The segregation of the alleles of this marker and the plasma ACE levels were studied in a group of F2 rats issued from a cross between Lou and BN rats. The degree of genetic determination of plasma ACE activity was estimated to be 94% in the F2 cohort. The ACE locus accounts for 74% of total plasma ACE variance. ACE activity and mRNA expression in lungs were also genetically determined. The difference observed in ACE mRNA accumulation in the lungs between the two strains was due to a difference in the transcriptional rate of the ACE gene, as shown in nuclear run-on experiments. No differences were observed in arterial blood pressure of homozygous F2 progeny. In these animals, ACE genotype did not interfere with the pressor or the depressor responses to ACE-dependent vasoactive peptides. There was a significant effect of strain on constitutive or inducible membrane or soluble ACE activity in primary cultures of vascular cells. Neointima formation in the carotid artery 14 days after balloon injury was also influenced by the genotype in F2 homozygous progeny, whereas the medial area was not. These results demonstrate that there is a close relationship between the genetically determined ACE expression and the inducibility of the ACE gene. The degree of genetic determination of ACE expression in inbred rat strains offers a unique opportunity to study the interaction between genetic and environmental determinants of ACE expression and its involvement in response to experimental cardiovascular and renal injury.

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.

Angiotensin-Converting Enzyme Gene and Atherosclerosis

Common variants of the angiotensin-converting enzyme (ACE) gene ( ACE in humans, Ace in mice) associated with changes in circulating ACE activities have been suggested to confer differential risks for atherosclerosis. Using a mouse model of atherosclerosis induced by heterozygosity for apolipoprotein E gene disruption and an atherogenic diet, we have studied the impact on atherogenesis of a mutation that changes the level of function of Ace . We find that this genetically determined change does not influence the size or complexity of atherosclerotic lesions. Ace genotype was not a significant determinant of lesion size in female (+/+=12.9±1.5 and +/-=1 1.7±1.6 μm 2 ×l0 4 ) or male (+/+=0.95±0.25 and +/-=1.83±0.59 μm 2 ×l0 4 ) mice; however, lesions were significantly larger ( P <.001) in female than male mice. Ace genotype also did not affect lesion complexity; however, lesions in females showed significantly increased frequency of cholesterol clefts, acellular cores, fibrous caps, and calcifications compared with those in males. The hypothesis that genetic variation in the level of ACE gene expression affects the development of atherosclerosis is not supported by these findings. ( Arterioscler Thromb Vase Biol. 1997;17:1245-1250.)