Angiotensin-converting enzyme gene polymorphism and cardiovascular endocrine system in coronary angiography patients

Influence of the angiotensin converting enzyme insertion or deletion genetic variant and coronary restenosis risk: evidence based on 11,193 subjects

The insertion/deletion (I/D) polymorphism of the gene encoding angiotensin converting enzyme is a controversial risk factor for restenosis after percutaneous transluminal coronary angioplasties (PTCA) in patients. Genetic association studies can be problematic to reproduce due to insufficient power, phenotypic heterogeneity, population stratification, small effect of the variant and even publication biases. To derive a more precise estimation of the relationship as well as to quantify the between-study heterogeneity and potential bias, a meta-analysis including 11,193 patients from 33 published cohort studies was performed. In a combined analysis, the summary per-allele odds ratio for restenosis was 1.31 (95% CI: 1.08-1.58, P = 0.006), and 1.22 (95% CI: 0.95-1.56, P = 0.12), for PTCA-stent and PTCA-balloon, respectively. In the subgroup analysis by ethnicity, significantly increased restenosis risks after PTCA-stent were found in Asians for the polymorphism; whereas no significant associations were found among Caucasians. As for restenosis risks after PTCA-balloon, no evidence of any gene-disease association was obtained in the stratified analyses according to ethnicity and study size. In conclusion, this meta-analysis demonstrated that the DD homozygous of ACE I/D polymorphism was significantly associated with elevated restenosis susceptibility after PTCA-stent among Asian populations.

Genetic polymorphism of angiotensin converting enzyme and risk of coronary restenosis after percutaneous transluminal coronary angioplasties: evidence from 33 cohort studies

Background

In the past decade, a number of cohort studies studies have been carried out to investigate the relationship between the insertion/deletion polymorphism of the gene encoding angiotensin-converting enzyme and risk of restenosis after percutaneous transluminal coronary angioplasties in patients. However, these studies have yielded contradictory results. Genetic association studies addressing this issue are frequently hampered by insufficient power. We therefore performed a meta-analysis of the published studies to clarify this inconsistency and to establish a comprehensive picture of the relationship between ACE I/D polymorphism and post-PTCA restenosis risk.

Methods

Databases including Pubmed, EMBASE, ISI Web of Science, EBSCO, Cochrane Library databases and CNKI were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. The random-effects model was applied, addressing heterogeneity and publication bias.

Results

A total of 33 cohort studies involving 11,099 subjects were included. In a combined analysis, the OR for post-PTCA restenosis of the ACE DD genotype was 1.61 (95% CI: 1.27–2.04; P<10⁻⁵). In the subgroup analysis by intervention, significantly increased risks were also found in PTCA-stent and PTCA-balloon for the DD genotype of the polymorphism.

Conclusions

Our meta-analysis showed that the DD genotype of ACE I/D polymorphism was significantly associated with increased risk of restenosis, particularly for PTCA-stent.

Renin-angiotensin system genetic polymorphisms: lack of association with CRP levels in patients with coronary artery disease

Angiotensin (Ang) II is believed to be a potential pro-inflammatory factor. The capability of Ang II to stimulate C-reactive protein (CRP) production has recently been described. Genetic polymorphisms of renin angiotensin system (RAS) components have been described to be associated with the development of coronary artery disease (CAD). This study investigated the association between six different genetic polymorphisms of RAS and serum CRP levels in a sample of CAD patients. Genotyping of RAS genes polymorphisms in 176 patients with documented CAD was performed by a modified polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Measurement of high-sensitivity (hs)-CRP was performed using standard immunoturbidimetric methods. Results show no significant differences in serum CRP regarding different variants of the six polymorphisms studied (p = 0.41, 0.24, 0.25, 0.19, 0.29, and 0.05 for Ang-converting enzyme (ACE) insertion/deletion (I/D), A-240T and A2350G, angiotensinogen M235T, AT1 receptor A1166C, and AT2 receptor C3123A polymorphisms, respectively). In conclusion, genetic polymorphisms of RAS are not associated with increased serum CRP in CAD. Compensation of an increased activity of ACE through counter-regulation and the secretion of CRP under the influence of Ang II in the vessel being local could explain the lack of association between the studied polymorphisms and CRP levels in CAD patients.

Association of echocardiographic left ventricular structure with the ACE D/I polymorphism: a meta-analysis

Introduction: In a previous meta-analysis, we derived pooled estimates for the association of left ventricular mass (LVM) and hypertrophy (LVH), as diagnosed by electrocardiography or echocardiography, with the ACE D/I polymorphism. We updated this meta-analysis until May 2009 only considering echocardiographic phenotypes.

Methods: We computed pooled estimates from a random-effects model.

Results: Across 38 studies, both DD homozygotes ( n = 2440) and DI heterozygotes ( n = 4310) had higher ( p ≤ 0.002) LVM or LVM index than II homozygotes ( n = 2229). Across 21 studies with available data, this was due to increased mean wall thickness (MWT) with no difference in left ventricular internal diameter (LVID). Standardised differences (DD versus II) were 0.39 ( p < 0.001) for LVM, 0.34 ( p = 0.009) for MWT, and 0.066 ( p = 0.26) for LVID. Across 16 studies (4894 participants), the pooled odds ratios of LVH (versus II homozygotes) were 1.11 ( p = 0.29) and 1.02 ( p = 0.88) for the DD and DI genotypes, respectively. Sensitivity analyses were confirmatory.

Conclusions: Our meta-analysis supports the hypothesis that the enhanced ACE activity associated with the D allele is associated with higher LV mass. Smaller sample size might explain the lack of significant association with LVH.

ACE (I/D) polymorphism and response to treatment in coronary artery disease: a comprehensive database and meta-analysis involving study quality evaluation

BACKGROUND

The role of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in modifying the response to treatment modalities in coronary artery disease is controversial.

METHODS

PubMed was searched and a database of 58 studies with detailed information regarding ACE I/D polymorphism and response to treatment in coronary artery disease was created. Eligible studies were synthesized using meta-analysis methods, including cumulative meta-analysis. Heterogeneity and study quality issues were explored.

RESULTS

Forty studies involved invasive treatments (coronary angioplasty or coronary artery by-pass grafting) and 18 used conservative treatment options (including anti-hypertensive drugs, lipid lowering therapy and cardiac rehabilitation procedures). Clinical outcomes were investigated by 11 studies, while 47 studies focused on surrogate endpoints. The most studied outcome was the restenosis following coronary angioplasty (34 studies). Heterogeneity among studies (p < 0.01) was revealed and the risk of restenosis following balloon angioplasty was significant under an additive model: the random effects odds ratio was 1.42 (95% confidence interval:1.07-1.91). Cumulative meta-analysis showed a trend of association as information accumulates. The results were affected by population origin and study quality criteria. The meta-analyses for the risk of restenosis following stent angioplasty or after angioplasty and treatment with angiotensin-converting enzyme inhibitors produced non-significant results. The allele contrast random effects odds ratios with the 95% confidence intervals were 1.04(0.92-1.16) and 1.10(0.81-1.48), respectively. Regarding the effect of ACE I/D polymorphism on the response to treatment for the rest outcomes (coronary events, endothelial dysfunction, left ventricular remodeling, progression/regression of atherosclerosis), individual studies showed significance; however, results were discrepant and inconsistent.

CONCLUSION

In view of available evidence, genetic testing of ACE I/D polymorphism prior to clinical decision making is not currently justified. The relation between ACE genetic variation and response to treatment in CAD remains an unresolved issue. The results of long-term and properly designed prospective studies hold the promise for pharmacogenetically tailored therapy in CAD.

Exonization of AluYa5 in the human ACE gene requires mutations in both 3' and 5' splice sites and is facilitated by a conserved splicing enhancer

Ancient Alu elements have been shown to be included in mature transcripts by point mutations that improve their 5′ or 3′ splice sites. We have examined requirements for exonization of a younger, disease-associated AluYa5 in intron 16 of the human ACE gene. A single G>C transversion in position −3 of the new Alu exon was insufficient for Alu exonization and a significant inclusion in mRNA was only observed when improving several potential splice donor sites in the presence of 3′ CAG. Since complete Alu exonization was not achieved by optimizing traditional splicing signals, including the branch site, we tested whether auxiliary elements in AluYa5 were required for constitutive inclusion. Exonization was promoted by a SELEX-predicted heptamer in Alu consensus sequence 222–228 and point mutations in highly conserved nucleotides of this heptamer decreased Alu inclusion. In addition, we show that Alu exonization was facilitated by a subset of serine/arginine-rich (SR) proteins through activation of the optimized 3′ splice site. Finally, the haplotype- and allele-specific ACE minigenes generated similar splicing patterns in both ACE-expressing and non-expressing cells, suggesting that previously reported allelic association with plasma ACE activity and cardiovascular disease is not attributable to differential splicing of introns 16 and 17.

Polymorphisms of the insertion / deletion ACE and M235T AGT genes and hypertension: surprising new findings and meta-analysis of data

Background

Essential hypertension is a common, polygenic, complex disorder resulting from interaction of several genes with each other and with environmental factors such as obesity, dietary salt intake, and alcohol consumption. Since the underlying genetic pathways remain elusive, currently most studies focus on the genes coding for proteins that regulate blood pressure as their physiological role makes them prime suspects.

The present study examines how polymorphisms of the insertion/deletion (I/D) ACE and M235T AGT genes account for presence and severity of hypertension, and embeds the data in a meta-analysis of relevant studies.

Methods

The I/D polymorphisms of the ACE and M235T polymorphisms of the AGT genes were determined by RFLP (restriction fragment length polymorphism) and restriction analysis in 638 hypertensive patients and 720 normotensive local blood donors in Weisswasser, Germany. Severity of hypertension was estimated by the number of antihypertensive drugs used.

Results

No difference was observed in the allele frequencies and genotype distributions of ACE gene polymorphisms between the two groups, whereas AGT TT homozygotes were more frequent in controls (4.6% vs. 2.7%, P = .08). This became significant (p = 0.035) in women only. AGT TT genotype was associated with a 48% decrease in the risk of having hypertension (odds ratio: 0.52; 95% CI, 0.28 to 0.96), and this risk decreased more significantly in women (odds ratio: 0.28; 95% CI, 0.1 to 0.78). The meta-analysis showed a pooled odds ratio for hypertension of 1.21 (TT vs. MM, 95% CI: 1.11 to 1.32) in Caucasians. No correlation was found between severity of hypertension and a specific genotype.

Conclusion

The ACE I/D polymorphism does not contribute to the presence and severity of essential hypertension, while the AGT M235T TT genotype confers a significantly decreased risk for the development of hypertension in the population studied here. This contrasts to the findings of meta-analyses, whereby the T allele is associated with increased risk for hypertension.

Relation between the angiotensin-converting enzyme insertion/deletion polymorphism and blood pressure in Japanese male subjects

Inconsistent results have been reported regarding the association of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and hypertension. Recent studies of population-based samples of three different areas in Japan presented conflicting results regarding this association. We, thus, investigated the relation between the ACE I/D polymorphism and blood pressure (BP), or the frequency of hypertension, respectively, in 706 Japanese male subjects who participated in the health check-up programme of our hospital. The ACE I/D polymorphism was determined by the polymerase chain reaction technique. Of 706 subjects, 203 were found to have hypertension and the other 503 were found to be normotensive. In all subjects, the frequencies of the DD, ID, and II genotypes were 0.123, 0.432, and 0.445, respectively, and the allelic frequency of the D allele was 0.339. In the younger subjects aged <50 years (n=264), neither systolic nor diastolic BP differed significantly among the genotypes. Conversely, in the older subjects aged > or =50 years (n=442), the systolic BP was significantly higher by 5.9 mmHg in the subjects with the ID genotype than those with the II genotype (P<0.01), and the diastolic BP was significantly higher in the subjects with the DD and ID genotypes by 5.1 and 3.3 mmHg, respectively than those with the II genotype (P<0.05 for each), although age, BMI, percentage of smoking habits, drinking habits, or the use of antihypertensive drugs did not differ significantly among the genotypes. In addition, in the older subjects, the hypertensive subjects showed significantly higher frequencies of the DD and ID genotypes and the D allele than the normotensive subjects. These results demonstrated that there was no significant association of the ACE I/D polymorphism with BP or a prevalence of hypertension in younger Japanese men aged <50 years but there was in older Japanese men aged > or =50 years.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

Endothelin-1 and vasopressin plasma levels are not associated with the insertion/deletion polymorphism of the human angiotensin I-converting enzyme gene in patients with coronary artery disease

The objective was to investigate whether the renin-angiotensin (RA) system and related peptides endothelin-1 (ET-1) and vasopressin (VP) influence the development of coronary artery disease (CAD). Angiotensin I-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism has been associated with the risk of CAD. The ACE I/D polymorphism determines ACE activity, but plasma levels of other RA system components remain unchanged. However, ET-1 and VP production could be increased by RA system-dependent stimulation, continually promoted by paracrine stimulation and sustained by neointimal growth. ET-1 and VP have not been associated with the ACE I/D polymorphism so far. The present study investigated the association of the ACE I/D polymorphism with plasma concentrations of ET-1 and VP, as well as with renin, angiotensin-II (AT-II) and ACE activity in 98 Caucasian individuals with CAD. ACE I/D polymorphism showed no association with plasma levels of VP, ET-1, AT-II or renin. These parameters were also not associated taking into consideration different patient variables, such as diabetes mellitus, hypertension or severity of CAD. Only plasma ACE activity was associated with the D allele. In conclusion, the ACE I/D polymorphism could not be related to plasma concentrations of VP, ET-1, renin or AT-II, but as previously demonstrated, it could only be related to ACE activity in patients with CAD. Differences in ACE activity between ACE I/D genotype subgroups are probably compensated within the RA system itself or within non-ACE pathways, so that plasma concentrations of the related peptides ET-1 and VP remain unaffected.

Cerebrovascular disorders and genetic polymorphisms: mitochondrial DNA5178C is predominant in cerebrovascular disorders

We studied polymorphisms of mitochondrial DNA 5178cytosine/adenine (mt5178C/A) and angiotensin I-converting enzyme (ACE) genes (DCP1) in 127 cerebrovascular disorder (CVD) patients and 294 age-matched normal controls to clarify the genetic background of Japanese patients with CVD. Mt5178C was predominant in CVD patients compared with controls (P<0.01). The frequency of DCP1 insertion (I) and deletion (D) alleles showed no significant difference between the CVD patients and controls or between each CVD subgroup. Although the number of CVD patients in the present study was too small to make a final conclusion, mt5178C might be one of the genetic factors to be considered in Japanese patients with CVD.

Relationship of angiotensin converting enzyme genotype with serum triglyceride concentration in stroke patients

The Objective of this research was to study the relationship of angiotensin converting enzyme (ACE) genotype with serum triglycerides concentration in stroke patients. The insertion/deletion (I/D) ACE polymorphism was identified by using polymerase chain reaction in 122 prospectively studied ischemic stroke patients (age 45-91 years). Serum triglycerides concentration was determined at admission and 3 months after the stroke, and compared between the ACE genotype groups (37 D/D, 68 D/I, 17 I/I). All clinical characteristics were similar in the three groups. Patients with D/D genotype had mean serum triglycerides concentration significantly higher in acute (179.0+/-111.8 mg/dl) and chronic phase (176.4+/-121.6 mg/dl) than those with I/I genotype (acute phase: 108.7+/-36.1 mg/dl, P=0.019; chronic phase: 116.0+/-44.3 mg/dl, P=0.021). The results showed that serum triglycerides concentration is elevated in stroke patients with the DD ACE genotype and it may be related to the risk of cerebrovascular disease associated with this polymorphism.

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.