Polymorphisms in the RAS and cardiac function

Genetic variation-optimized treatment benefit of angiotensin-converting enzyme inhibitors in patients with stable coronary artery disease: a 12-year follow-up study

OBJECTIVES

The objective of this study was to examine the relationship between renin-angiotensin system genotypes and the pharmacogenetics of angiotensin-converting enzyme (ACE) inhibitors in Chinese patients with coronary artery disease (CAD).

METHODS

Patients with angiographic CAD were recruited from 1995 to 2003. The baseline characteristics and genetic polymorphisms [ACE gene insertion/deletion (I/D) polymorphisms, six polymorphisms of the angiotensinogen (AGT) gene, and A-1166C polymorphisms of the angiotensin-II type I receptor gene (AGT1R)] were established. Patients were divided into two groups (ACE inhibitor or no ACE inhibitor) and followed for up to 12 years. Kaplan-Meier curves and Cox regression models were used to determine the survival and major cardiovascular events (MACE) event-free survival trends. Pharmacogenetic effects were determined by several Cox regression models.

RESULTS

Of the 784 patients, 432 were treated with ACE inhibitors and 352 were not. ACE inhibitors were associated with a lower MACE rate at 4000 days. In addition, the ACE I/D gene D and AGT1R gene C alleles were associated with a higher MACE rate on the basis of a multivariate regression analysis. This effect was attenuated by the pharmacogenetic interaction of ACE inhibitors and the ACE gene (ACE inhibitors* ACE gene, hazard ratio: 0.8, 95% confidence interval: 0.62-0.94, P=0.03).

CONCLUSIONS

ACE inhibitors were associated with a significant decrease in MACE in Chinese patients diagnosed with CAD. Genetic variants were also associated with event-free survival, but their effects were modified by the use of ACE inhibitors.

N-domain isoform of Angiotensin I converting enzyme as a marker of hypertension: populational study

The aim of this paper was to investigate the presence of the urinary 90 kDa N-domain ACE in a cohort of the population from Vitoria, Brazil, to verify its association with essential hypertension since this isoform could be a possible genetic marker of hypertension. Anthropometric, clinical, and laboratory parameters of the individuals were evaluated (n = 1150) and the blood pressure (BP) was measured. The study population was divided according to ACE isoforms in urine as follows: ACE 65/90/190, presence of three ACE isoforms (n = 795), ACE 90⁺ (65/90) (n = 186), and ACE 90⁻ (65/190) (n = 169) based on the presence (+) or absence (−) of the 90 kDa ACE isoform. The anthropometric parameters, lipid profile, serum levels of uric acid, glucose, and the systolic and diastolic BP were significantly greater in the ACE 90⁺ compared with the ACE 90⁻ and ACE 65/90/190 individuals. We found that 98% of individuals from the ACE 90⁺ group and 38% from the ACE 65/90/190 group had hypertension, compared to only 1% hypertensive individuals in the ACE 90⁻ group. There is a high presence of the 90 kDa N-domain ACE isoform (85%) in the studied population. The percentile of normotensive subjects with three isoforms was 62%. Our findings could contribute to the development of new efficient strategy to prevent and treat hypertension to avoid the development of cardiovascular disease.

Influences of the G2350A polymorphism in the ACE gene on cardiac structure and function of ball game players

Background

Except for the I/D polymorphism in the angiotensin I-converting enzyme (ACE) gene, there were few reports about the relationship between other genetic polymorphisms in this gene and the changes in cardiac structure and function of athletes. Thus, we investigated whether the G2350A polymorphism in the ACE gene is associated with the changes in cardiac structure and function of ball game players. Total 85 healthy ball game players were recruited in this study, and they were composed of 35 controls and 50 ball game players, respectively. Cardiac structure and function were measured by 2-D echocardiography, and the G2350A polymorphism in the ACE gene analyzed by the SNaPshot method.

Results

There were significant differences in left ventricular mass index (LVmassI) value among each sporting discipline studied. Especially in the athletes of basketball disciplines, indicated the highest LVmassI value than those of other sporting disciplines studied (p < 0.05). However, there were no significant association between any echocardiographic data and the G2350A polymorphism in the ACE gene in the both controls and ball game players.

Conclusions

Our data suggests that the G2350A polymorphism in the ACE gene may not significantly contribute to the changes in cardiac structure and function of ball game players, although sporting disciplines of ball game players may influence the changes in LVmassI value of these athletes. Further studies using a larger sample size and other genetic markers in the ACE gene will be needed.

Prevalence of the angiotensin I converting enzyme gene insertion/deletion polymorphism in a healthy Turkish population

Angiotensin converting enzyme (ACE) plays an essential role in the renin-angiotensin system. It converts angiotensin I to angiotensin II and inactivates bradykinin and tachykinins. Numerous studies have been published investigating associations of the ACE gene I/D polymorphism with various pathophysiological conditions. We examined the prevalence of the ACE I/D polymorphism in a sample of healthy volunteers from western Turkey, including 1063 healthy Turkish controls. Analysis of the ACE I/D gene polymorphisms by polymerase chain reaction found frequencies of 16.1% for the II genotype, 47.7% for the ID genotype, and 36.2% for the DD genotype. The allele frequency was 39.9% for the I alleles and 60.1% for the D allele. This study demonstrates that the allele and genotype frequency values for the Turkish population are similar to previously published frequencies for Caucasian populations.

RAS gene polymorphisms, classical risk factors and the advent of coronary artery disease in the Portuguese population

Background

Several polymorphisms within the renin-angiotensin system cluster of genes have been associated with the advent of coronary artery disease (CAD) or related pathologies. We investigated the distribution of 5 of these polymorphisms in order to find any association with CAD development and distinguish if any of the biochemical and behavioural factors interact with genetic polymorphisms in the advent of the disease.

Methods

ACE I/D (rs4340), ACE A11860G (rs4343), AT1R A1166C (rs5186), AGT T174M (rs4762) and AGT M235T (rs699) gene polymorphisms were PCR-RFLP analysed in 298 CAD patients and 510 controls from Portugal. Several biochemical and behavioural markers were obtained.

Results

ACE I/D DD and ACE11860 GG genotypes are risk factors for CAD in this population. The simultaneous presence of ACE I/D I and ACE11860 A alleles corresponds to a significant trend towards a decrease in CAD incidence. We found several synergistic effects between the studied polymorphisms and classical risk factors such as hypertension, obesity, diabetes and dyslipidaemia: the presence of the DD genotype of ACE I/D (and also ACE11860 GG) increases the odds of developing CAD when associated to each one of these classical risk factors, particularly when considering the male and early onset CAD subgroup analysis; AGT235 TT also increases the CAD risk in the presence of hypertension and dyslipidaemia, and AT1R1166 interacts positively with hypertension, smoking and obesity.

Conclusion

ACE polymorphisms were shown to play a major role in individual susceptibility to develop CAD. There is also a clear interaction between RAS predisposing genes and some biochemical/environmental risk factors in CAD onset, demonstrating a significant enhancement of classical markers particularly by ACE I/D and ACE11860.

Genetic variants predisposing to cardiovascular disease

PURPOSE OF REVIEW

The goal of this review is to provide an update on the most recent and relevant findings in the area of genotype-phenotype associations as well as the relationships between genetic factors and cardiovascular disease risk markers and events. In addition, emphasis will be placed on the methodological problems associated with studying the genetics of complex disorders, specifically cardiovascular diseases.

RECENT FINDINGS

Genes associated with cardiovascular disease predisposition have been examined, including traditional cardiovascular disease candidate genes, such as ACE, AGT, eNOS, PON and MTHFR, new loci that have recently been added to the growing list of cardiovascular disease candidate genes (i.e. MEF2A, ALOX5, LTA, APOM, PDE4D), and genes that have been shown to be at the intersection of several age-related disorders through interaction with one another or with environmental factors (i.e. APOA5, APOE, PPARgamma, LPL and LIPC).

SUMMARY

During the last year, tremendous effort has been made in elucidating new genes associated with cardiovascular disease predisposition. For the most part, however, major breakthroughs have not been made, primarily due to the poor replication of results among studies, as a consequence of poor experimental design. Nevertheless, we have increased our understanding of the complexity of cardiovascular disease and the relevance of gene-environment interactions as the ultimate drivers of the individual predisposition to the disease. It is essential, therefore, that present and future genetic studies in this area take into consideration the inclusion of high-quality environmental data in the analytical process to test the clinical usefulness of a genetic marker as a risk predictor.

Genes and human elite athletic performance

Physical fitness is a complex phenotype influenced by a myriad of environmental and genetic factors, and variation in human physical performance and athletic ability has long been recognised as having a strong heritable component. Recently, the development of technology for rapid DNA sequencing and genotyping has allowed the identification of some of the individual genetic variations that contribute to athletic performance. This review will examine the evidence that has accumulated over the last three decades for a strong genetic influence on human physical performance, with an emphasis on two sets of physical traits, viz. cardiorespiratory and skeletal muscle function, which are particularly important for performance in a variety of sports. We will then review recent studies that have identified individual genetic variants associated with variation in these traits and the polymorphisms that have been directly associated with elite athlete status. Finally, we explore the scientific implications of our rapidly growing understanding of the genetic basis of variation in performance.

Mortality in patients with hypertension on angiotensin-I converting enzyme (ACE)-inhibitor treatment is influenced by the ACE insertion/deletion polymorphism

BACKGROUND

The response to angiotensin-I converting enzyme (ACE)-inhibitor therapy is highly variable. Residual ACE activity during treatment, potentially modified by the ACE insertion/deletion (I/D) polymorphism, may explain part of this variability. We studied the possible interaction between ACE-inhibitor therapy in patients with hypertension and the ACE I/D polymorphism in incident heart failure and death.

METHODS

We studied 3365 hypertensive participants of the population-based Rotterdam Study, without heart failure at baseline for whom ACE-genotyping was successful. Incident heart failure was defined according to established criteria. In addition, total and cardiovascular mortality were studied as endpoints. A Cox regression model with use of ACE-inhibitors defined as time-dependent covariates was used for data-analysis. Interaction was tested in this model assuming an allele-effect relationship.

RESULTS

Although we could not demonstrate a beneficial effect of ACE-inhibitors, there was significant interaction between the ACE I/D polymorphism (II-ID-DD) and ACE-inhibitor use in the prediction of total and cardiovascular mortality. Mortality risk associated with treatment increased with the number of D alleles present; e.g. for total mortality in the II genotype group: RR=0.95 (95% CI 0.63-1.45), in the ID genotype group: RR=1.08 (95% CI 0.84-1.38) and in the DD genotype group: RR=1.61 (95% CI 1.18-2.18). No statistically significant interaction was found for incident heart failure.

CONCLUSION

The results of our study suggest a relative resistance to ACE-inhibitor therapy in subjects with hypertension and the DD genotype compared to the II genotype, with the ID genotype in an intermediate position.

Association of Angiotensin Converting Enzyme Gene Polymorphisms with Left Ventricular Hypertrophy

The angiotensin converting enzyme gene (ACE) is of much interest as a candidate gene conferring an individual's genetic susceptibility to left ventricular hypertrophy (LVH). LVH has long been thought to be an end point of essential hypertension (EH), rather than a separate entity, though it is influenced by a unique set of hormonal, vascular and genetic factors. In this study, we attempted to determine whether two representative polymorphisms of the ACE gene, ACE I/D and 2350 G>A, known to be associated with EH and to have a highly significant influence on plasma ACE levels, could implicate ACE as a quantitative trait locus (QTL) for LVH. We carried out a retrospective, case-control study of the two ACE polymorphisms amongst 180 nationals (50 LVH patients and 130 controls) from the United Arab Emirates (Emirati)--an ethnic group characterized by an absence of alcohol intake and cigarette smoking--for putative correlations with LVH. Clinical diagnoses of LVH were based on echocardiographic and ECG criteria. ACE I/D and 2350 G>A genotypes were determined by polymerase chain reaction (PCR) and restriction digestion. Univariate and multivariate logistic regression analyses revealed an association between ACE polymorphisms and LVH. Haplotype analysis further supported this finding. The ACE I/D and ACE 2350 G>A polymorphisms were in strong linkage disequilibrium and were independently associated with LVH, suggesting that ACE is likely to be a QTL for LVH. In conclusion, This is the first association study of the ACE 2350 G>A polymorphism with LVH; the results showed that this polymorphism, along with ACE I/D, is associated with LVH.