Insertion/deletion polymorphism in the angiotensin-converting enzyme gene affects heart weight

Influence of angiotensin II type 1 receptors and angiotensin-converting enzyme I/D gene polymorphisms on the progression of Chagas' heart disease in a Brazilian cohort: Impact of therapy on clinical outcomes

Chagas disease (CD), a neglected tropical disease, is caused by infection by the protozoan Trypanosoma cruzi. One-third of CD patients develop cardiac disease (CARD), an inflammatory and fibrotic process that may progress to heart failure associated with reduced left ventricular ejection fraction (LVEF). The determinants of CD progression are still uncertain. In non-infectious conditions, the angiotensin-converting enzyme (ACE) functional insertion (I)/deletion (D) and type 1 angiotensin II receptor (AT1R) +1166A>C gene polymorphisms have been linked to clinical outcomes. In a Brazilian cohort of 402 patients with positive serology for CD, in a case-control study we used PCR for genotyping the ACE rs4646994 I/D and AGTR1 rs5182C>T, rs275653 -119C>T, rs2131127A>G and rs5186 +1166A>C polymorphisms to evaluate association with CARD and progression to heart failure. Patients were classified as non-CARD (stage A; 109), and mild (stage B1; 161) or severe (stage C; 132) CARD. The groups were compared using unconditional logistic regression analysis and adjusted for non-genetic covariates (age, gender, and trypanocidal treatment). ACE II genotype appeared less frequent in C patients (15% in C vs 20% in B1 and 27% in A). After covariate adjustments, the ACE D allele showed a borderline association with susceptibility to severe CARD (C vs A: OR = 1.9; P = 0.08). AGTR1 +1166AC genotype showed a borderline association with protection against the progression and severity of CARD (C vs A: OR = 0.6; P = 0.09; C vs B1: OR = 0.6; P = 0.07; C vs A + B1: OR = 0.6; P = 0.05). However, adjustments for multiple comparisons showed no association of ACE I/D and AGTR1 polymorphisms with susceptibility and severity of CARD. The rs275653/rs2131127/rs5186/rs5182 T/A/C/T haplotype was protective against progression to the severe form of CARD (C vs B1: OR = 0.3; P = 0.03). Moreover, patients with ACE II and AGTR1 rs5186 +1166AC genotypes presented higher LVEF%. In C patients, TNF serum levels were higher in ACE D carriers than in II genotype. Although limited in number, a cross-sectional observation suggests that C-stage patients treated with benznidazole years prior to administration of ACE inhibitors/AT1R antagonists show reduced TNF serum levels and improved LVEF%. Therefore, variants of ACE and AGTR1 genes may influence the outcome of Chagas' heart disease and should be explored in precision medicine. Further, pharmacotherapies may improve immunological abnormality and clinical outcome in CD patients. Altogether, these data support prospective studies of this cohort and replication in other cohorts.

Influence of Angiotensin-converting Enzyme Insertion/Deletion Gene Polymorphism in Progression of Chagas Heart Disease

INTRODUCTION

Chagas disease (CD) is a neglected disease caused by the parasite Trypanosoma cruzi. One-third of infected patients will develop the cardiac form, which may progress to heart failure (HF). However, the factors that determine disease progression remain unclear. Increased angiotensin II activity is a key player in the pathophysiology of HF. A functional polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with plasma enzyme activity. In CD, ACE inhibitors have beneficial effects supporting the use of this treatment in chagasic cardiomyopathy.

METHODS

We evaluated the association of ACE I/D polymorphism with HF, performing a case-control study encompassing 343 patients with positive serology for CD staged as non-cardiomyopathy (stage A; 100), mild (stage B1; 144), and severe (stage C; 99) forms of Chagas heart disease. For ACE I/D genotyping by PCR, groups were compared using unconditional logistic regression analysis and adjusted for nongenetic covariates: age, sex, and trypanocidal treatment.

RESULTS

A marginal, but not significant (p=0.06) higher prevalence of ACE I/D polymorphism was observed in patients in stage C compared with patients in stage A. Patients in stage C (CD with HF), were compared with patients in stages A and B1 combined into one group (CD without HF); DD genotype/D carriers were prevalent in the HF patients (OR = 2; CI = 1.013.96; p = 0.04).

CONCLUSIONS

Our results of this cohort study, comprising a population from the Northeast region of Brazil, suggest that ACE I/D polymorphism is more prevalent in the cardiac form of Chagas disease with HF.

A Designed Experiment: Polymorphism Analysis of Angiotensin-Converting Enzyme Gene from Human Buccal Epithelial Cells

For medical students, we combine the laboratory practice with clinical applications by developing biochemical and molecular biology experiments. In this experiment, students first collect their own buccal epithelial cells by a noninvasive mouthwash method. Then, they extract genomic DNA and perform polymerase chain reaction (PCR) to amplify angiotensin-converting enzyme (ACE) gene using genomic DNA as a template. Finally, the polymorphism of ACE gene is observed by electrophoresis. Students not only learn the techniques but also acquire knowledge of the ACE gene polymorphism. By establishing the relationship among ACE polymorphism and high blood pressure and myocardial hypertrophy, students should be able to understand the gene polymorphism and its association with susceptibility to disease. This laboratory practice teaching can also stimulate desire to do scientific research. Experimental results from many individuals can help us determine and analyze the fractions of ACE gene types in Chinese cohorts. Such an experiment strongly activates students and provides a solid foundation for the medical students' future research and clinical application. © 2019 International Union of Biochemistry and Molecular Biology, 47(2): 168-174, 2019.

The genomic architecture of sporadic heart failure

Common or sporadic systolic heart failure (heart failure) is the clinical syndrome of insufficient forward cardiac output resulting from myocardial disease. Most heart failure is the consequence of ischemic or idiopathic cardiomyopathy. There is a clear familial predisposition to heart failure, with a genetic component estimated to confer between 20% and 30% of overall risk. The multifactorial etiology of this syndrome has complicated identification of its genetic underpinnings. Until recently, almost all genetic studies of heart failure were designed and deployed according to the common disease-common variant hypothesis, in which individual risk alleles impart a small positive or negative effect and overall genetic risk is the cumulative impact of all functional genetic variations. Early studies used a candidate gene approach focused mainly on factors within adrenergic and renin-angiotensin pathways that affect heart failure progression and are targeted by standard pharmacotherapeutics. Many of these reported allelic associations with heart failure have not been replicated. However, the preponderance of data supports risk-modifier effects for the Arg389Gly polymorphism of β1-adrenergic receptors and the intron 16 in/del polymorphism of angiotensin-converting enzyme. Recent unbiased studies using genome-wide single nucleotide polymorphism microarrays have shown fewer positive results than when these platforms were applied to hypertension, myocardial infarction, or diabetes, possibly reflecting the complex etiology of heart failure. A new cardiovascular gene-centric subgenome single nucleotide polymorphism array identified a common heat failure risk allele at 1p36 in multiple independent cohorts, but the biological mechanism for this association is still uncertain. It is likely that common gene polymorphisms account for only a fraction of individual genetic heart failure risk, and future studies using deep resequencing are likely to identify rare gene variants with larger biological effects.

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.

Angiotensin-converting enzyme insertion/deletion gene polymorphism and progression of Chagas' cardiomyopathy

Chagas' disease is common in Latin America and is caused by Trypanosoma cruzi. It is usually associated with chronic cardiomyopathy, the progression of which could be related to genetic factors. As alterations in the renin-angiotensin-aldosterone system have been reported in the disease, the aim of this study was to determine whether associated genetic polymorphisms influence the development of myocardial damage. The study involved 125 patients who were divided into two groups according to whether they had mild or severe cardiomyopathy. The insertion/deletion polymorphism of the angiotensin-converting enzyme gene was investigated using standard techniques and results were correlated with disease stage. The genotypes were in Hardy-Weinberg equilibrium. After adjusting for demographic variables, no significant relationship was found between the polymorphism and progression of chronic Chagas' disease. Although our sample was limited, the results suggest that the progression of cardiomyopathy in chronic Chagas' disease is unrelated to the insertion/deletion polymorphism.

Angiotensin-converting enzyme insertion/deletion gene polymorphism and progression of Chagas' cardiomyopathy

Chagas' disease is common in Latin America and is caused by Trypanosoma cruzi. It is usually associated with chronic cardiomyopathy, the progression of which could be related to genetic factors. As alterations in the renin-angiotensin-aldosterone system have been reported in the disease, the aim of this study was to determine whether associated genetic polymorphisms influence the development of myocardial damage. The study involved 125 patients who were divided into two groups according to whether they had mild or severe cardiomyopathy. The insertion/deletion polymorphism of the angiotensin-converting enzyme gene was investigated using standard techniques and results were correlated with disease stage. The genotypes were in Hardy-Weinberg equilibrium. After adjusting for demographic variables, no significant relationship was found between the polymorphism and progression of chronic Chagas' disease. Although our sample was limited, the results suggest that the progression of cardiomyopathy in chronic Chagas' disease is unrelated to the insertion/deletion polymorphism.

Interaction of BMP10 with Tcap may modulate the course of hypertensive cardiac hypertrophy

Elevated wall stress by hypertension induces an adaptive myocardial hypertrophy via releasing prohypertrophic hormones such as angiotensin II. In this study, we investigated the involvement of bone morphogenetic protein-10 (BMP10) in hypertension-induced cardiac hypertrophy. Expression of BMP10 was increased in the hypertrophied ventricles from hypertensive rats. BMP10 localized on cell surface and at stretch-sensing Z disc of cardiomyocytes, where BMP10 interacted with a protein called titin-cap (Tcap). A rare variant of the human BMP10 gene, Thr326Ile, was found to be associated with hypertensive dilated cardiomyopathy. The variant BMP10 demonstrated decreased binding to Tcap and increased extracellular secretion. Conditioned medium from cells transfected with wild-type or variant BMP10 induced hypertrophy in rat neonatal cardiomyocytes, except that medium from variant BMP10-carrying cells showed an enhanced effect reflecting the increased secretion. These observations suggested that hypertension induced expression of prohypertrophic BMP10, and the hypertrophic effect of BMP10 was modulated, at least in part, by its binding to Tcap at the Z disc.

Small gene effect and exercise training-induced cardiac hypertrophy in mice: an Ace gene dosage study

Small gene effects influence complex phenotypes in a context dependent manner. Here we evaluated whether increasing dosage of the angiotensin I converting enzyme ( Ace) gene influence exercise-induced cardiac hypertrophy. Mice harboring one, two, three, and four copies of the Ace gene were assigned to sedentary (S1–4) and swimming exercise-trained (T1–4) groups (1.5 h twice daily, 5 days/wk, 4 wk). Exercising resulted in comparable bradycardia and elevated skeletal muscle citrate synthase activity, while blood pressure remained unchanged. Left ventricle mass index and cardiomyocyte diameter were similar among sedentary mice and the magnitude of their increase associated to exercising was not influenced by the Ace genotype (T1: 12.6 and 17.9%, T2: 15.2 and 13.8%, T3: 16.9 and 20%, T4: 17 and 19%, respectively). Plasma renin activity (PRA) levels were higher in one vs. three or four copies mice (4.89 ± 0.5 vs. 2.43 ± 0.6 and 2.12 ± 01.1 ng/ml Ang I, P < 0.05), while cardiac ACE activity was higher in three vs. two or one copy mice (5,946 ± 590.8 vs. 2,951.5 ± 328.3 and 3,504.1 ± 258.9 μF·min−1·ml−1, P < 0.05). With exercise, PRA remained unchanged in each group, while cardiac immunostaining for Ang II reached comparable levels. In summary: 1) exercise training led to similar aerobic adaptation regardless of the Ace genotype, and 2) higher number of Ace gene copies per se, which alters cardiac ACE activity, did not influence basal cardiac mass or, most importantly, the magnitude of swimming-induced cardiac hypertrophy. Collectively, these data indicate that small isolated genetic disturbances in ACE cardiac levels can be well compensated under physiological perturbations.

Association of estrogen receptor alpha gene polymorphisms with neurofibrillary tangles

Estrogen receptor alpha (ERalpha) may be implicated in the pathogenesis of Alzheimer's disease (AD). The aim of this study was to clarify the association between ERalpha gene polymorphisms and AD-related pathologic changes. The staging of neurofibrillary tangles (NFT) and senile plaques (SP) was performed according to the method by Braak and Braak and two polymorphisms, PvuII (P or p) and XbaI (X or x), of the ERalpha gene were typed in 551 Japanese cadavers (294 men and 257 women; mean age, 80.8 years). Distributions of the NFT and SP stages significantly correlated with age (NFT: r = 0.306, p < 0.0001; SP: r = 0.237, p < 0.0001) and were significantly higher in patients with the apolipoprotein E epsilon4 allele (p < 0.0001). Possession of the P allele showed a trend to be associated with a more serious NFT stage, but had no relationship with the SP stage. In men, a significant association between PvuII polymorphism and the NFT stage (p = 0.002) was found, revealing a gene- dose effect of the P allele. Similar results were obtained in the men without the epsilon4 allele (p = 0.011). Multiple regression analyses demonstrated that age was the strongest determinant of the NFT stage, possession of the epsilon4 allele was the next strongest, and PvuII polymorphism was the third strongest (p < 0.0001, R(2) = 0.144). The XbaI polymorphism did affect neither the NFT stage nor the SP stage. In conclusion, the PvuII polymorphism of the ERalpha gene is associated with Braak NFT stages and possession of the P allele may act as a risk factor for AD in Japanese men, especially in those without the epsilon4 allele.

Developments of geriatric autopsy database and Internet-based database of Japanese single nucleotide polymorphisms for geriatric research (JG-SNP)

To facilitate geriatric research on the roles of genetic polymorphisms of candidate genes, two databases were developed based on data obtained from autopsy examinations of elderly subjects: the geriatric autopsy database (GEAD) and the Japanese single nucleotide polymorphisms (SNP) database for geriatric research (JG-SNP) which is accessible on the Internet (http://www.tmgh.metro.tokyo.jp/jg-snp/english/E_top.html). The data for the GEAD were derived from 1074 consecutive autopsy cases (565 male and 509 female cases) with an average age of 80 years. The GEAD was installed on a stand-alone Windows 2000 server using Oracle 8i as the database application. The GEAD contains clinical diagnoses of 26 geriatric diseases, histories of smoking and alcohol consumption, pathological findings (720 items), severity of atherosclerosis, genetic polymorphism data, etc. On the JG-SNP website, case distribution corresponding to a specified SNP or disease can be searched or downloaded. Although there are several Internet-based SNP databases such as dbSNP, no databases are available at present on the web that contain both SNP data and phenotypic data. As autopsy studies can provide large amounts of accurate medical information, including the presence of undiagnosed diseases such as latent cancers, the GEAD is a unique and excellent database for research on genetic polymorphisms.

The Role of Angiotensin-Converting Enzyme Polymorphism in Congestive Heart Failure

Angiotensin-converting enzyme (ACE) is a zinc metallopeptidase, with primary known functions of converting angiotensin I into the vasoactive and aldosterone-stimulating peptide angiotensin II and inactivating bradykinin. There is high variability among individuals in ACE concentrations, mainly due to the presence of a genetic polymorphism. The ACE gene has, in fact, insertion/deletion polymorphism in intron 16, consisting of a 287-base pair Alu repeat sequence, with three genotypes: insertion polymorphism, insertion/deletion polymorphism, and deletion polymorphism. The genetic effect accounts for 47% of the total variance of serum ACE. The determination of this polymorphism has allowed researchers to study the implications of the ACE gene in many case-control studies of cardiovascular disease, including myocardial infarction and hypertrophic and dilated cardiomyopathy. We review the current knowledge about the ACE gene polymorphism and its implications in heart failure secondary to ischemic or idiopathic dilated cardiomyopathy. Interpretation of the results of studies about the role of this polymorphism are controversial. The repetition of epidemio-genetic studies and the creation of adequate experimental studies will help to definitively establish the pathogenetic role of the permanent increase in ACE expression associated with the deletion polymorphism genotype.

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.

Left ventricular size, mass and function in relation to angiotensin-converting enzyme gene and angiotensin-II type 1 receptor gene polymorphisms in patients with coronary artery disease

The objective of the present study was to analyse the potential synergistic influence of the insertion/deletion polymorphism of the angiotensin-converting enzyme gene (I/D ACE) and the A1166C polymorphism of the angiotensin-II type 1 receptor gene polymorphisms (A1166C AT1R) on the left ventricular size and performance. Three hundred sixty and one consecutive, Caucasian patients with angiographically confirmed coronary artery disease (CAD) were enrolled into the study. Left ventricular diameter, mass and function were evaluated by echocardiography. Screening for the I/D ACE and A1166C AT1R genotypes was performed by polymerase chain reaction of genomic DNA, followed by restriction enzyme digestion and agarose gel electrophoresis. The I/D ACE and A1166C AT1R genotypes separately were not significantly associated with the left ventricular size and function parameters in CAD patients. However, trends towards decreased left ventricular ejection fraction (LVEF) as well as increased left ventricular end-diastolic diameter (LVEDD) and left ventricular mass index (LVMI) were observed when patients with genotype DD+CC/AC and DD+CC were compared to patients homozygous only in one locus (DD or CC). Significant increase in LVEDD and LVMI was observed only in patients with a history of anterior myocardial infarction with combined genotype DD+CC/AC or DD+CC. This study does not support the role of the ACE I/D and AT1R A1166C polymorphisms in the determination of the left ventricular size and performance in patients with significant coronary atherosclerosis. However, it indicates that the influence of polymorphisms may be present in specific patient populations.

Microfluidic chip-based method for genotyping microsatellites, VNTRs and insertion/deletion polymorphisms

We have developed a method to genotype variable number of tandem repeats (VNTRs) and insertion/deletion polymorphisms using an integrated microfluidic chip-based system. We used this method to analyze a) a highly polymorphic pentanucleotide repeat (CCTTT)(n) locus within the 5'-putative promoter region of the human inducible nitric oxide synthase gene (iNOS5) which is associated with diabetic complications and infectious diseases; b) a bi-allelic 27 bp VNTR region within intron 4 of endothelial nitric oxide gene (eNOS27) which is associated with hypertension in type 2 diabetes patients with coronary heart disease and excess risk of advanced diabetic nephropathy in type 1 diabetes patients and c) an insertion/deletion polymorphism within the gene encoding angiotensin-converting enzyme (ACE/ID) which is associated with cardiovascular pathology and nitric oxide activity, and is in strong linkage disequilibrium with functional variants. Following amplifications, samples were mixed with gel-dye and markers and loaded into commercially available microfluidic chips designed for DNA sizing applications. In the study (N = 230), 95 (41%) of the DNA samples were homozygous and 135 (59%) were heterozygous for the iNOS5 repeats. For eNOS27, 173 (75%) of the genotyped DNA samples were homozygous for the larger 4b allele and the remaining 57 samples (25%) were heterozygous (4b/4a). No DNA samples were homozygous for the shorter 4a allele with four 27 bp repeats. In case of ACE/ID, 47 (20%) of the DNA samples were homozygous for the insertion, 65 (28%) were homozygous for the deletion and the remaining 118 (51%) were heterozygous. The results obtained were verified by analyzing random amplicons using bi-directional sequencing and GeneScan 3.0 analyses with 100% concordance being observed. Using the microfluidic chip-based method, separation and DNA sizing and genotyping are rapidly accomplished. The DNA fragments are resolved clearly and the system allows quantitation. Finally, the microfluidic chip-based method may be used for both large- and small-scale genotyping studies.

Age-related mitochondrial DNA deletion in human heart: its relationship with cardiovascular diseases

BACKGROUND AND AIMS

Accumulation of damage to mitochondrial DNA (mtDNA) occurs in myocardial tissue with advancing age. However, despite higher incidence of cardiac diseases in the elderly, little attempt has been made to detect deletions of mtDNA in the myocardial tissue of aged individuals. The aim of the present study was to clarify the relationship between aging, mtDNA deletion and cardiovascular (CV) diseases.

METHODS

We examined 163 autopsy cases, aged 60 years or older, using two different kinds of polymerase chain reaction (PCR): highly sensitive PCR to detect a common 4977-bp deletion and long-PCR for multiple deletions, which could be detected in case that deleted mtDNA accounted for more than several percents in total mtDNA.

RESULTS

The common 4977-bp deletion was detected in 156 cases (95.7%), showing no significant difference among these age groups and no relation to CV diseases. By long-PCR, multiple deletions in cardiac mtDNA were found in 33 (20.2%) of 163 cases. The proportion of the mtDNA deletion in the nineties (46.2%) was significantly higher than those in the younger (15.3%, p < 0.05). Female predominance was significantly found in the group with the mtDNA deletion (p < 0.05). Multiple deletions of mtDNA were not significantly related to ischemic change, valvular diseases, left ventricular hypertrophy, congestive heart failure, coronary sclerosis, or heart weight except for right ventricular hypertrophy.

CONCLUSIONS

These findings suggest that there is a close relationship between aging and deletion of mtDNA, and that the ratio of deleted mtDNA to total mtDNA increases with advancing age. Age-related deletion of mtDNA may have little influence on CV diseases except for right ventricular hypertrophy.

ACE gene polymorphism as a prognostic indicator in patients with type 2 diabetes and established renal disease

OBJECTIVE

To investigate whether the DD genotype is a predictor of mortality and of the decline in renal function in patients with type 2 diabetes and established nephropathy.

RESEARCH DESIGN AND METHODS

A total of 56 such patients of Maltese Caucasian descent were recruited, and their ACE genotype was determined. Serum creatinine was estimated approximately every 4 months. The glomerular filtration rate (GFR) was calculated according to the Cockroft-Gault formula, and rate of change was determined by regression analysis.

RESULTS

The rate of change in calculated GFR was -7.76 ml.min(-1).year(-1) in those with the DD genotype (n = 31) and -1.17 ml. min(-1). h(-1) in those with the ID or II genotype (n = 25) (P < 0.01). The 3-year mortality was 45.2% in the DD group compared with 20.0% in the ID/II group (P < 0.05).

CONCLUSIONS

The DD genotype of the ACE gene polymorphism is associated with a more rapid decline in renal function and higher mortality in type 2 diabetic patients with established nephropathy.

Renin-angiotensin system gene polymorphisms: potential mechanisms for their association with cardiovascular diseases

Since the first description of the angiotensin-converting enzyme insertion/deletion polymorphism more than a decade ago, many hundreds of investigations have reported associations between this polymorphism and cardiovascular diseases. Subsequently, similar studies were performed in relationship with several other renin-angiotensin system gene polymorphisms, most notably the angiotensinogen M235T polymorphism and the angiotensin AT(1) receptor A1166C polymorphism. Surprisingly however, especially in view of the many contradictory results that have been obtained, very little attention has been paid to the mechanism(s) that may link these genetic variants and respective diseases. Here, we review the limited evidence that is currently available on the functional consequences (including compensatory mechanisms) of the above three renin-angiotensin system gene polymorphisms, in order to provide an explanation for the reported associations (or lack thereof) between these polymorphisms and cardiovascular diseases.