Angiotensin-converting enzyme gene polymorphism and cardiovascular disease

Angiotensin-Converting Enzyme (ACE) 1 Gene Polymorphism and Phenotypic Expression of COVID-19 Symptoms

The renin–angiotensin–aldosterone system (RAAS) appears to play an important role in SARS-CoV-2 infection. Polymorphisms within the genes that control this enzymatic system are candidates for elucidating the pathogenesis of COVID-19, since COVID-19 is not only a pulmonary disease but also affects many organs and systems throughout the body in multiple ways. Most striking is the fact that ACE2, one of the major components of the RAAS, is a prerequisite for SARS-COV-2 infection. Recently, we and other groups reported an association between a polymorphism of the ACE1 gene (a homolog of ACE2) and the phenotypic expression of COVID-19, particularly in its severity. The ethnic difference in ACE1 insertion (I)/deletion (D) polymorphism seems to explain the apparent difference in mortality between the West and East Asia. The purpose of this review was to further evaluate the evidence linking ACE1 polymorphisms to COVID-19. We searched the Medline database (2019–2021) for reference citations of relevant articles and selected studies on the clinical outcome of COVID-19 related to ACE1 I/D polymorphism. Although the numbers of patients are not large enough yet, most available evidence supports the notion that the DD genotype adversely influences COVID-19 symptoms. Surprisingly, small studies conducted in several countries yielded opposite results, suggesting that the ACE1 II genotype is a risk factor. This contradictory result may be the case in certain geographic areas, especially in subgroups of patients. It may also be due to interactions with other genes or to yet unexplained biochemical mechanisms. According to our hypothesis, such candidates are genes that are functionally involved in the pathophysiology of COVID-19, can act in concert with the ACE1 DD genotype, and that show differences in their frequency between the West and East Asia. For this, we conducted research focusing on Alu-related genes. The current study on the ACE1 genotype will provide potentially new clues to the pathogenesis, treatment, and diagnosis of SARS-CoV-2 infections.

Atherosclerotic and thrombotic genetic and environmental determinants in Egyptian coronary artery disease patients: a pilot study

BACKGROUND

Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide. Multiple genetic variants in combination with various environmental risk factors have been implicated. This study aimed to investigate the association of twelve thrombotic and atherosclerotic gene variants in combination with other environmental risk factors with CAD risk in a preliminary sample of Egyptian CAD patients.

METHODS

Twenty three consecutive CAD patients undergoing diagnostic coronary angiography and 34 unrelated controls, have been enrolled in the study. Genotyping was based on polymerase chain reaction and reverse multiplex hybridization. Five genetic association models were tested. Data distribution and variance homogeneity have been checked by Shapiro-Wilk test and Levene test, respectively; then the appropriate comparison test was applied. Spearman's rank correlation coefficient was used for correlation analysis and logistic regression has been performed to adjust for significant risk factors. Clustering the study participants according to gene-gene and gene-environment interaction has been done by Detrended Correspondence Analysis (DCA).

RESULTS

The univariate analysis indicated that the five variants; rs1800595 (FVR2; factor 5), rs1801133 (MTHFR; 5,10-methylenetetrahydrofolate reductase), rs5918 (HPA-1; human platelet antigen 1), rs1799752 (ACE; angiotensin-converting enzyme), and rs7412 and rs429358 (ApoE; apolipoprotein E) were significantly associated with CAD susceptibility under different genetic models. Multivariate analysis revealed clustering of the study population into three patient groups (P) and one control group. FVR2 was the most variant associated with CAD patients, combined with the factor V Leiden (FVL) variant in P1 cluster and with both ACE and MTHFR 667C > T in P2. Whereas, P3 was mostly affected by both MTHFR 667C > T and FXIII (factor 13) V89L mutations. When combined with traditional risk factors, P1 was mostly affected by dyslipidemia, smoking and hypertension, while P2 was mostly affected by their fasting blood sugar levels and ApoE variant.

CONCLUSIONS

Taken together, these preliminary results could have predictive value to be applied in refining a risk profile for our CAD patients, in order to implement early preventive interventions including specific antithrombotic therapy. Further large scale and follow-up studies are highly recommended to confirm the study findings.

Angiotensin-converting enzyme genotype and peripheral arterial disease in diabetic patients

We investigated the effect of traditional risk factors (hypertension, dyslipidemia and smoking) on the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and peripheral arterial disease (PAD) in 945 (454 men and 491 women) Taiwanese type 2 diabetic patients with a mean age of 63.5 (SD: 11.4) years. Among them, 81 (31 men and 50 women) had PAD (ankle-brachial index <0.9). The adjusted odds ratios (95% confidence intervals) were 2.48 (1.18–5.21), 1.69 (1.00–2.85) and 1.64 (1.12–2.39), respectively, for recessive (DD versus II + ID), dominant (DD + ID versus II) and additive (II = 0, ID = 1 and DD = 2) models. While analyzing the interaction between DD and the individual risk factor of hypertension, smoking and dyslipidemia, patients with the risk factor and with DD had the highest risk compared to referent patients without the risk factor and with II/ID. The respective adjusted odds ratios were 5.41 (2.05–14.31), 7.38 (1.87–29.06) and 4.64 (1.70–12.64). We did not find a significant interaction between DD and any of the risk factors under multiplicative or additive scale. In conclusion, traditional risk factors (hypertension, smoking and dyslipidemia) play an important role in the association between ACE genotypes and PAD. Patients with DD genotype and traditional risk factors are at the highest risk.

Genetic polymorphisms influence runners' responses to the dietary ingestion of antioxidant supplementation based on pequi oil (Caryocar brasiliense Camb.): a before-after study

Genes have been implicated in the levels of oxidative stress, lipids, CVD risk, immune reactivity, and performance. Pequi oil (Caryocar brasiliense) has shown anti-inflammatory and hypotensive effects, besides reducing exercise-induced DNA, tissue damages, and anisocytosis. Given that diet can interact with the human genome to influence health and disease, and because genetic variability can influence response to diet, we aim to investigate the influence of 12 gene polymorphisms on inflammatory markers, postprandial lipids, arterial pressure, and plasma lipid peroxidation of runners (N = 125), before and after 14 days of 400 mg pequi-oil supplementation, after races under closely comparable conditions. Arterial pressure was checked before races; blood samples were taken immediately after racing to perform leukogram and plateletgram, Tbars assay, lipid, and CRP dosages and genotyping. CAT, GST-M1/T1, CRP-G1059C, and MTHFR-C677T polymorphisms influenced post-pequi-oil responses in leukogram; Hp and MTHFR-C677T, in plateletgram; Hp, ACE, GSTT1, and MTHFR-A1298C, in lipid profile; MTHFR-A1298C, in C-reactive protein (CRP) levels; and Hp and MnSOD, in Tbars assay. Differences between ACE genotypes in leukogram and total cholesterol disappeared after pequi, and the same occurred for Hp and MnSOD in Tbars assay and for MTHFR-A1298C with CRP levels. Because genetic inheritance is one of the factors that drive atherosclerosis-related lipid abnormalities, results can contribute to a greater understanding of the influence of genetic polymorphisms in situations that push up free radicals. Knowledge is also expanded on how antioxidant supplementation affects an individual's genes and how athletic genetic makeup can affect the way a person responds to antioxidant supplements.

Angiotensin-converting enzyme insertion/deletion polymorphism has no effect on the risk of atherosclerotic stroke or hypertension

BACKGROUND AND PURPOSE

Stroke is a heterogeneous multifactorial disease. Hence, a large number of candidate genes are involved in stroke pathophysiology, such as blood pressure regulation and atherosclerosis. Although angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism is considered to have a role in hypertension, coronary artery disease, and myocardial infarction, its relationship with cerebrovascular disease and hypertension in stroke in different ethnic populations is still inconsistent.

METHODS

ACE I/D polymorphism, detected by polymerase chain reaction (PCR), was studied in 97 patients with large-vessel and 60 patients with small-vessel atherosclerotic stroke (44 asymptomatic, 16 symptomatic lacunes) and 85 healthy subjects with normal brain imaging. The demographic data, lipid profile and risk factors of patients and controls were obtained retrospectively.

RESULTS

ACE genotypes were in Hardy-Weinberg equilibrium in both patients and controls. Prevalences of DD, ID and II genotype were 41%, 40%, and 19%, respectively, in the stroke group. Differences in ACE I/D polymorphism distribution were statistically insignificant between the groups. This lack of association between stroke and ACE I/D polymorphism did not change in the presence of traditional risk factors (hypertension, diabetes mellitus, smoking, and dyslipidemia). Although hypertension was significantly more common in the patient groups, ACE I/D polymorphism showed no effect on hypertension risk. This lack of association also did not change according to groups or in the presence of diabetes mellitus, male gender or smoking.

CONCLUSION

ACE I/D polymorphism did not predict the risk of stroke or hypertension in our population living in the western Black Sea region of Turkey.

Association between the insertion/deletion polymorphism of the angiotensin-converting enzyme gene and erectile dysfunction in patients with metabolic syndrome

This study was designed to investigate whether angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism is associated with erectile dysfunction (ED) in Russian men with metabolic syndrome (MS). A total of 331 men with MS were studied. All patients underwent complex evaluation including the International Index of Erectile Function (IIEF) questionnaire. The ACE I/D polymorphism was determined by polymerase chain reaction. Overall, 182 men (55.0%) had ED according to the IIEF erectile function domain score. In the ED group, the prevalence of DD genotype was found to be significantly higher compared to the non-ED group (P<0.001). In both groups, patients with DD genotype were significantly younger than patients with other genotypes (P<0.001). In addition, in the ED group, the disease affected patients with DD genotype at a significantly younger age (P<0.001). Obtained results give evidence to support the finding that the D allele is a risk factor for the micro- and macrovascular diseases.

Angiotensin-converting enzyme gene polymorphism and stroke in type 2 diabetic patients in Taiwan

BACKGROUND

The effect of traditional risk factors on the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and stroke was rarely studied previously. We investigated such effect in Taiwanese type 2 diabetic patients.

MATERIALS AND METHODS

A total of 872 (422 men and 450 women) patients aged 63.5 (SD: 11.6) years were recruited. Among them, 92 cases (48 men and 44 women) had stroke. Polymerase chain reaction was used to classify the genotypes as II, ID and DD. Analyses were performed in separate sexes.

RESULTS

The adjusted odds ratios for stroke for ID vs. II and DD vs. II were 0.837 (0.413-1.697) and 1.778 (0.596-5.300), respectively, for men; but were 1.700 (0.824-3.505) and 3.706 (1.375-9.985), respectively, for women. In models assuming recessive (DD vs. II + ID), dominant (DD + ID vs. II) and additive (II = 0, ID = 1 and DD = 2) transmission, none of the odds ratios was significant for men; but were all significant for women: 2.784 (1.137-6.818), 1.996 (1.006-3.962) and 1.877 (1.155-3.050), respectively. In models using patients without risk factors (hypertension, obesity, smoking or dyslipidaemia ) as a referent group and comparing them to patients with the risk factor and with ID/II, and with DD genotypes, all models (except for smoking) favoured an increasing trend of risk with patients having the risk factor and DD genotype at the highest risk in women. Similar trends for hypertension and dyslipidaemia were also observed in men.

CONCLUSION

Traditional risk factors play an important role in the association between the ACE genotypes and stroke. Patients with DD genotype and having traditional risk factors are at the highest risk.

A cladistic model of ACE sequence variation with implications for myocardial infarction, Alzheimer disease and obesity

Sequence variation in ACE, which encodes angiotensin I converting enzyme, contributes to a large proportion of variability in plasma ACE levels, but the extent to which this impacts upon human disease is unresolved. Most efforts to associate ACE with other heritable traits have involved a single Alu insertion/deletion polymorphism, despite the probable existence of other functional sequence variants with effects that may not be consistently detectable by solely typing the Alu indel. Here, utilizing single nucleotide polymorphisms (SNPs) that differentiate major ACE clades in European populations, we demonstrate a number of significant phenotype associations across more than 4000 Swedish individuals. In a systematic analysis of metabolic phenotypes, effects were detected upon several traits, including fasting plasma glucose levels, insulin levels and measures of obesity (P-values ranging from 0.046 to 8.4 x 10(-6)). Extending cladistic models to the study of myocardial infarction and Alzheimer disease, significant associations were observed with greater effect sizes than those typically obtained in large-scale meta-analyses based on the Alu indel. Population frequencies of ACE genotypes were also found to change with age, congruent with previous data suggesting effects upon longevity. Clade models consistently outperformed those based upon single markers, reinforcing the importance of taking into consideration the possible confounding effects of allelic heterogeneity in this genomic region. Utilizing computational tools, potential functional variants are highlighted that may underlie phenotypic variability, which is discussed along with the broader implications these results may have for studies attempting to link variation in ACE to human disease.

Smoking-dependent effects of the angiotensin-converting enzyme gene insertion/deletion polymorphism on blood pressure

BACKGROUND

Studies on the role of the angiotensin-converting enzyme (ACE) gene in the development of hypertension have yielded conflicting results. Recent studies suggested that this gene might have smoking-dependent effects on the development of cardiovascular disease.

OBJECTIVE

To study the relationship between the ACE insertion/deletion (I/D) polymorphism, blood pressure and risk of hypertension in current, former and non-smokers in a population-based cohort.

METHODS

We included 2412 non-smokers, 2794 former smokers and 1508 current smokers, all participants in the Rotterdam Study. In each group, we assessed the relationship between the ACE I/D polymorphism, systolic (SBP) and diastolic (DBP) blood pressures and risk of hypertension. Mean blood pressures and prevalence of hypertension were compared between carriers and non-carriers of the D allele. All analyses were adjusted for age, sex, body mass index, diabetes mellitus, high-density lipoprotein cholesterol, total cholesterol and use of antihypertensive medication.

RESULTS

In non-smokers and former smokers, blood pressure and the risk of hypertension did not differ significantly between genotypes. In smokers, we found a significant increase in SBP in DD carriers (139.6 +/- 22.8 mmHg) compared with II carriers (136.0 +/- 22.7 mmHg) (P = 0.04). No effect of ACE genotype was observed for DBP. The risk of hypertension was significantly increased in smokers who carried one [odds ratio (OR) 1.4, 95% confidence interval (CI) 1.0 to 1.9; P = 0.05] or two (OR 1.5, 95% CI 1.1 to 2.2; P = 0.02) copies of the D allele.

CONCLUSIONS

The D allele of the ACE polymorphism is associated with a significantly increased SBP and risk of hypertension in smokers. Our study underlines the importance of gene-environment interactions in the study of candidate genes for hypertension.

The renin-angiotensin-aldosterone system and Alzheimer s disease?

Epidemiological studies from the last decade have begun to produce evidence that the perceived joint occurrence of vascular disease and Alzheimer's disease (AD), both common elderly disorders more often believed to occur by chance due to their high prevalence, may now actually have a more pathological significance. The following review discusses some of this evidence and the implications for cognitive decline and the development of AD and how a well-known cardiovascular risk factor gene, the apolipoprotein E (APOE) gene, plays a significant role in the molecular genetics of AD. It also introduces and discusses recent and compelling evidence for the involvement of another well-known cardiovascular risk factor gene, the angiotensin-converting enzyme (ACE1) gene, in the pathogenesis of AD. This role is suggested in terms of recent molecular genetic association evidence implicating the ACE1 insertion/deletion (indel) polymorphism, a more recent large haplotype study that greatly extends the ACE1 indel evidence and incorporates knowledge accrued from previous cardiovascular disease-focused ACE1 haplotype studies. Finally, this paper discusses very recent biological evidence that further supports a role for ACE1 and hypothesises a number of readily testable mechanisms by which the ACE1 enzyme and other components of the renin-angiotensin-aldosterone system may be implicated in increased risk and/or the progression of AD.

Genetic polymorphisms in the Renin-Angiotensin system in high-altitude and low-altitude Native American populations

Cardiovascular disease (CVD) is reportedly less common in high-altitude native populations than in lowlanders. To some extent, this is due to cultural and demographic factors; however, increased cardiovascular efficiency contributing to hypoxia adaptation may also be involved. Numerous genetic variants have been associated with cardiovascular health. If the decreased incidence of CVD in modern high-altitude populations reflects selective pressures having favoured the transmission of these alleles in their antecedents, it would be expected that these alleles would be more common in highlanders than in lowlanders. We tested this hypothesis by determining the allele frequencies of five polymorphic loci in genes encoding components of the renin-angiotensin system (RAS) that have alleles associated with hypertension and cardiovascular disease in a high-altitude native Andean population, Quechua from the Peruvian altiplano, and in a lowland Amerindian population, Maya from the Yucatan peninsula. The polymorphisms examined were 1) the insertion/deletion polymorphism in intron 16 of the angiotensin converting enzyme (ACE) gene; 2) the A/G2350 transition (ACE-8) in intron 17 of the ACE gene; 3) the A/C1166 transversion in the 3' untranslated region of the angiotensin II receptor (type 1) gene (AGTR1); 4) the G/AI9-83 transition in intron 8 of the renin gene (REN); and 5) the T/C704 (Met235Thr) transition mutation in angiotensinogen (AGT). There was no evidence for an over-representation of the RAS alleles associated with cardiovascular fitness in the high-altitude Amerindian population when compared to the lowland Amerindian population.

Increased frequency of angiotensin-converting enzyme DD genotype in Saudi overweight and obese patients

BACKGROUND

Several studies have been carried out to investigate the insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) in obese and normal weight individuals, often with contradictory results in different populatios. In some studies, the DD genotype occurs at a high frequency in obesity, while in others no association has been demonstrated. Since obesity and overweight are of frequent occurrence in the Saudi population, we initiated this study to investigate the I/D polymorphism of ACE in obese, overweight and normal weight Saudis.

PATIENTS AND METHODS

The study group included 457 Saudi males and females. The height and weight were measured and body mass index (BMI) was calculated. Based on the BMI value, the total study population was classified as normal, overweight and obese. A total of 117 obese (BMI >30 (kg/m(2))), 185 overweight (BMI=25-29.9 (kg/m(2))) and 155 normal weight individuals (BMI< (kg/m (2)) were enrolled. Polymerase chain reaction (PCR) and agarose gel electrophoresis were used to study the ACE polymorphism. For the deletion (D) form, a 190 bp and for the insertion (I) form, 490 bp DNA fragment were obtained on 2% agarose gel electrophoresis.

RESULTS

The frequency of DD genotype was 76.9% in the obese, and 73.5% in the overweight individuals, compared to 19.66% and 24.86% of the ID genotype in the obese and overweight, respectively. Among the normal weight individuals, the frequency was significantly lower for DD and higher for the ID genotype, i.e., 58.7% for DD and 40% for ID. The allele frequencies in the obese were 0.867 and 0.133 for the D and I alleles, respectively. While in the overweight, the frequencies were 0.859 and 0.141 for these alleles, respectively, compared to 0.787 and 0.213 in the normal weight individuals.

CONCLUSIONS

The DD genotype and D allele occur at a high frequency in Saudi overweight and obese individuals, and may have some role in fat accumulation by affecting metabolic pathways of fat, thus leading to the development of overweight and obesity.

Lack of association between angiotensin-converting enzyme gene polymorphism and peripheral vascular disease in type 2 diabetic patients in Taiwan

A total of 361 Chinese patients with type 2 diabetes were studied for the association between peripheral vascular disease (PVD) and the insertion/deletion polymorphism involving a 287-bp alu repeat sequence at intron 16 of the angiotensin-converting enzyme (ACE) gene. The patients were divided into PVD (+) (n=45) and PVD (-) (n=316) based on an ankle-brachial index <0.9 and > or =0.9, respectively. Polymerase chain reaction was used to identify gene polymorphism. Results showed that D allele frequency in the patients without and with PVD was 31.8% and 33.3%, respectively (p=NS). The prevalence rates of II, ID and DD genotypes in the PVD (-) group were 45.6%, 45.3% and 9.2%, respectively; and the respective values for the PVD (+) group were 44.4%, 44.4% and 11.1% (p=NS). Prevalence rates of PVD in genotypes II, ID, and DD were 12.2%, 12.3% and 14.7%, respectively (p=NS). In logistic regression analyses, the unadjusted and adjusted odds ratios for DD vs II and ID vs II genotypes for PVD were not statistically significant. The respective adjusted odds ratios were 1.88 (0.56-6.29) and 1.33 (0.63-2.80). In conclusion, there was not a significant association between the ACE genotype and PVD in Chinese type 2 diabetic patients. However, a type 2 error can not be ruled out.

A prospective evaluation of the angiotensin-converting enzyme D/I polymorphism and left ventricular remodeling in the 'Healing and Early Afterload Reducing Therapy' study

The D/I (deletion, D, insertion, I) polymorphism of the angiotensin-converting enzyme (ACE) gene has been extensively studied for its association with a number of cardiovascular and other disease states. However, its potential association with differential clinical efficacy of ACE inhibitors (ACE-I) administered to patients who had suffered a myocardial infarction (MI), i.e. the prevention of left ventricular (LV) remodeling, has so far not been specifically studied. The aim of the study was to investigate whether the D/I polymorphism of the ACE gene is associated with the incidence of post-MI LV remodeling in patients drawn from the 'Healing and Early Afterload Reducing Therapy' (HEART) Study. The ACE D/I polymorphism was characterized by the polymerase chain reaction (PCR) in 265 subjects from the 'Healing and Early Afterload Reducing Therapy' Study, a double-blind, placebo-controlled trial with the objective of determining whether early or delayed administration of the ACE-I, ramipril, in patients with acute anterior wall MI would be optimal in reducing LV enlargement. Selected frequencies for the ACE D and I alleles were 0.59 and 0.41 (placebo-high dose group), 0.56 and 0.44 (low dose-low dose group), and, 0.60 and 0.40 (high dose-high dose group), respectively. All observed genotype frequencies were in Hardy-Weinberg equilibrium. There was no evidence for an association between genotype and outcome regarding LV size or function, nor with the initial blood pressure response after ACE-I administration (adjusted for covariates). Our data provide no evidence for an association of the ACE D/I polymorphism with the risk of LV remodeling post-MI in the presence of ACE-I therapy, and therefore do not suggest that differential clinical efficacy of ACE-inhibitors is related to this genetic marker.

ACE genotype and endothelium-dependent vasodilation of conduit arteries and forearm microcirculation in humans

The ACE gene is a candidate gene for cardiovascular disease. Endothelial dysfunction is considered an intermediate phenotype in the pathogenesis of hypertension and atherosclerosis. We evaluated the role of ACE gene polymorphism in endothelial function of young healthy humans. We assessed ACE genotype (deletion [D]/insertion [I] polymorphism) in 92 young healthy individuals. In 88 of them, endothelium-dependent (flow-mediated) vasodilation and endothelium-independent (nitroglycerin-induced) vasodilation were measured in the common femoral artery and in the brachial (n=84) artery by echo Doppler technique. In 35 subjects, we also applied the forearm perfusion technique to quantify the responses of the forearm vascular bed to 3 increasing doses of 2 endothelium-dependent vasodilators (acetylcholine and bradykinin) and 1 endothelium-independent vasodilator (sodium nitroprusside). The D allele of the ACE gene was associated with a significant blunting (Delta approximately 26%) of endothelium-dependent vasodilation in the femoral artery (P=0.02) but not in the brachial artery (P=0.55) or in the forearm microcirculation (P=0.70 to 0.80). Endothelium-independent vasodilation was unaffected by the ACE genotype. In young healthy humans, the D allele of the ACE gene is associated with selective endothelial dysfunction of the femoral artery. It remains to be determined whether this association discloses a causal role in vascular, particularly peripheral artery, disease.

Pregnancy outcomes and community health: the POUCH study of preterm delivery

In light of the social/ethnic disparity in preterm delivery (PTD) rates, the Pregnancy Outcomes and Community Health (POUCH) Study takes a broad view of the determinants of PTD by attempting to link underlying biological and psychosocial factors. The relationships between placental pathology, maternal biomarkers, and antecedent psychosocial factors are evaluated in three hypothesised pathways of PTD - one characterised primarily by infection, one by maternal vascular disease, and one by premature elevations in corticotropin releasing hormone in the absence of histological evidence of placental pathology. Within each pathway, an emphasis is placed on understanding the roles of stress and of maternal serum alpha-fetoprotein, an early biomarker associated with PTD. The POUCH Study enrolls pregnant women from five Michigan communities. Information about these women and their environments is gathered through detailed interviews and collection of biological samples including hair, urine, saliva, blood, vaginal fluid, and vaginal smear at 15-26 weeks of gestation. We have chosen to focus on the second trimester--a time when pathological processes may have evolved to a detectable stage, but generally before the onset of biological changes that accompany labour. This focus is consistent with the long-range goal of early detection/intervention and prevention of PTD.

Angiotensin-converting enzyme gene polymorphism in a cohort of coronary angiography patients

An association between a polymorphism of the angiotensin-converting enzyme (ACE) gene and myocardial infarction (MI) in men has been previously reported. The present study examines the association between ACE genotype, atherosclerosis, MI, hypertension and other cardiovascular risk factors in Caucasian men (n=576) and women (n=124) who have undergone coronary angiography. Gene frequencies are also reported for African-American men (n=56). Genotype determination was based on the presence (allele I) or absence (allele D) of a 287 nucleotide Alu sequence in intron 16 of the ACE gene. Genotype frequencies for DD, ID and II were: 30.9, 47.7, 21.4% for Caucasian men; 28.2, 48.4, 23.4% for Caucasian women; and 30.4, 46.4, 23.2% for African-American men. There were no statistically significant associations between ACE genotype and number of plaques (> or =10% obstruction), lipid variables, or body mass index (BMI) for Caucasian men. Caucasian women with the DD genotype had on average fewer plaques, but this was accounted for by their younger ages. In Caucasian males, the DD genotype independently contributed to the presence of hypertension (odds ratio=1.8, 95% CI 1.1-2.9) after adjusting for age and BMI. In Caucasian males with total cholesterol levels less than 200 mg/dl (n=237), the DD (odds ratio=2.5, 95% CI 1.2-5.4) and ID genotypes (odds ratio=2.2, 95% CI 1.1-4.4) were associated with a history of MI.

Exclusion of the ACE D/I gene polymorphism as a determinant of endothelial dysfunction

A deletion/insertion (D/I) polymorphism within the ACE gene may increase the risk of cardiovascular events through still unknown mechanisms. The latter may involve increased angiotensin II-induced NO breakdown and/or reduced agonist-mediated NO release. We therefore investigated whether the D allele of the ACE gene affects endothelium-dependent vasodilatation in mild-to-moderate primary hypertensive patients and healthy normotensive subjects. We compared in a cross-sectional study the forearm blood flow response of the 3 D/I genotypes with 5 incrementally increasing doses of the endothelium-dependent vasodilator acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 microg. 100 mL(-1). min(-1)) in 142 subjects: 103 mild-to-moderate uncomplicated primary hypertensives (49.3+/-9.1 years old, 152+/-11/99+/-5 mm Hg) and 39 normotensives (44.6+/-15.3 years old, 122+/-12/78+/-6 mm Hg). We also assessed the endothelium-independent vasodilatation in the forearm, as blood flow response to 3 incrementally increasing doses of sodium nitroprusside (1, 2, and 4 microg. 100 mL(-1). min(-1)). The overall genotype distribution was II, n=10; ID, n=70; and DD, n=62. It did not differ significantly between primary hypertensives and normotensives. A significant blunting of endothelium-dependent vasodilatation in primary hypertensive patients compared with normotensive subjects (P:<0.001) was found. No effect of the DI genotype on endothelium-dependent and -independent vasodilatation was detected. Thus, these results obtained in a relatively large population do not support the contention that the D allele is associated with a blunting of either stimulated endothelial NO or donated NO responses in both mild-to-moderate primary hypertensive patients and normotensive subjects.

The kallikrein-kininogen-kinin system: lessons from the quantification of endogenous kinins

The purpose of the present review is to describe the place of endogenous kinins, mainly bradykinin (BK) and des-Arg(9)-BK in the kallikrein-kininogen-kinin system, to review and compare the different analytical methods reported for the assessment of endogenous kinins, to explain the difficulties and the pitfalls for their quantifications in biologic samples and finally to see how the results obtained by these methods could complement and extend the pharmacological evidence of their pathophysiological role.

Regression of left ventricular hypertrophy by lisinopril after renal transplantation: role of ACE gene polymorphism

BACKGROUND

Cardiac complications are the main cause of death in renal transplantation (RT), and left ventricular hypertrophy (LVH) may play an important role in these patients. The unfavorable genotype of the angiotensin-converting enzyme (ACE) gene has been associated with cardiovascular disease, including LVH. ACE inhibitors (ACEIs) reduce LVH, but little is known about the effects of ACEIs on LVH in RT patients with different insertion/deletion (I/D) genotypes of the ACE gene.

METHODS

We prospectively studied 57 stable nondiabetic RT patients with hypertension and echocardiographic LVH as well as a functional graft for 69.5 +/- 5.6 months. Patients randomly received either lisinopril 10 mg/day (group A, N = 29; 5 were excluded due to reversible acute renal failure) or placebo (group B, N = 28) for 12 months. Echocardiography (M-mode, 2-B, and color flow Doppler) was performed at baseline and 6 and 12 months later by the same examiner without previous knowledge of the genetic typing. The ACE genotype (I or D alleles) was ascertained by polymerase chain reaction (PCR; group A, DD = 10 and ID/II = 14; group B, DD = 15 and ID/II = 13).

RESULTS

All patients maintained a good renal function (serum creatinine <2.5 mg/dL) during the follow-up and both groups received a similar proportion of antihypertensive drugs (beta-blockers 83 vs. 79%; Ca antagonists 66 vs. 68%; alpha1-adrenoreceptor antagonists 50 vs. 67%) during the study. As expected, mean arterial blood pressure and hemoglobin levels showed a higher percentage reduction in group A versus group B (-4 +/- 2.8 vs. 2.1 +/- 2.6%, P = 0.07, and -11.5 +/- 1.5 vs. -0.5 +/- 2.3%, P < 0.01, respectively). Group A patients showed a significantly higher decrement in LV mass index (LVMI) than group B at the end of follow-up, after adjusting for age, baseline LVMI, time after grafting and changes in systolic blood pressure, renal function, and hemoglobin levels (group A, -9.5 +/- 3.5% vs. group B, 3 +/- 3.2%, P < 0.05). As a result, 46% of group A and only 7% of group B patients showed a reduction of LVMI >/=15% (P < 0.01). The beneficial effect of lisinopril on LVMI reduction was more evident in DD patients (placebo DD, 8.4 +/- 4.1% vs. lisinopril DD, -7.2 +/- 5.3, P < 0.05), and a trend was observed in patients with other genotypes (placebo ID/II, 2.8 +/- 5.4% vs. lisinopril ID/II, -11.4 +/- 5%, P = 0.33).

CONCLUSIONS

Lisinopril decreases LVM in renal transplant patients with hypertension and LVH, and the ACE gene polymorphism may predict the beneficial effect of this therapy. This finding may be important in targeting prophylactic interventions in this population.

Genetic polymorphisms of the renin-angiotensin system and atheromatous renal artery stenosis

Genes that influence the renin-angiotensin system have been investigated in recent years as potential etiologic candidates of cardiovascular and renal diseases. In atheromatous renal artery stenosis (RAS), a condition characterized by persistent activation of the renin-angiotensin system, the study of these genes may be of particular relevance. We evaluated angiotensin-converting enzyme (ACE) insertion/deletion, angiotensinogen (AGT) M235T, and angiotensin II receptor (ATR) A1166C polymorphisms in relation to the occurrence of RAS. We studied 58 patients with angiographically documented RAS; 102 normotensive subjects with normal coronary arteries and no history or clinical or instrumental evidence of atherosclerosis in other vascular districts were considered the control group. Patients had a significantly higher D allele frequency (0.70 versus 0.55; chi(2) 6.88, P=0.01; odds ratio [OR] 1. 9, 95% CI 1.17 to 3.07) than did the control population; 48.3% of patients were homozygous for DD (chi(2) 6.62, P<0.05; OR 2.04, 95% CI 1.05 to 3.95); and only 8.6% carried the II genotype (OR 0.34, 95% CI 0.19 to 1.47). No significant association was found for AGT M235T and ATR A1166C. Our results suggest a predisposing role for ACE genetic polymorphism in the development and progression of atheromatous RAS.

Angiotensin-converting enzyme and cardiovascular disease risk

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

Angiotensin-converting enzyme (ACE) alleles in the Quechua, a high altitude South American native population

Recently it was reported that an allelic variant of the gene encoding angiotensin-converting enzyme (ACE) was significantly over-represented in a cohort of elite British mountaineers. It was proposed that this may be evidence for a specific genetic factor influencing the human capacity for physical performance. The implication that this allele could enhance performance at high altitude prompted us to determine its frequency in Quechua speaking natives living at altitudes greater than 3000m on the Andean Altiplano in South America. We found that the frequency of the putative performance allele in the Quechuas, although significantly higher than in Caucasians, was not different from lowland Native American populations. This observation suggests that, although the higher frequency of the 'performance allele' may have facilitated the migration of the ancestral Quechua to the highlands, the ACE insertion allele has not been subsequently selected for in this high altitude population.

A population study of ethnic variations in the angiotensin-converting enzyme I/D polymorphism: relationships with gender, hypertension and impaired glucose metabolism

BACKGROUND

The presence of the deletion allele of the angiotensin-converting enzyme (ACE) I/D polymorphism is associated with an excess risk of vascular disease and diabetic nephropathy.

OBJECTIVE

To examine the importance of this polymorphism as a determinant of hypertension and impaired glucose metabolism in a population-based study of three ethnic groups and assess the potential modifying effect of gender.

DESIGN

Population-based cross-sectional study in South London. The population-based sample of 1577 men and women, age 40-59 years, was obtained from stratified random sampling of general practice lists where 25% of the residents were born outside the UK. The ACE I/D polymorphism was determined for 1366 individuals (86.6%): 462 whites, 462 of African descent and 442 of South Asian origin.

RESULTS

The genotype frequency within each ethnic group was in Hardy-Weinberg equilibrium. The frequencies were similar in whites and those of African descent (II, ID, DD: 18.4%, 49.6%, 32.0% for whites and 18.4%, 50.5%, 30.9% for those of African descent), but there was a much higher frequency of the II genotype in those of South Asian origin (39.8%, 41.8%, 18.3%; chi2 = 77.6; P < 0.0001). There was no association between the I/D polymorphism and impaired glucose metabolism in any ethnic group. There were also no significant associations between the I/D polymorphism and hypertension in whites and in those of South Asian origin. This contrasts with a highly significant association between the D allele and hypertension in women of African descent (OR = 2.54; 95% CI 1.38-4.65; P = 0.003) but not in men of African descent (0.79; 0.36-1.72) (test for differences between sexes P = 0.023).

CONCLUSIONS

These observations provide estimates of the frequency distribution of the ACE I/D polymorphism in whites, in people of African descent and in people of South Asian origin. Moreover, these results highlight the potential importance of gender-dependent interactions between genetic background and expression of hypertensive phenotype.

DD angiotensin-converting enzyme gene polymorphism is associated with endothelial dysfunction in normal humans

A polymorphism within the angiotensin-converting enzyme (ACE) gene may increase the risk of myocardial infarction in individuals previously thought to be at low cardiovascular risk. The mechanism through which it exerts this effect is unknown but may be due to increased angiotensin II-induced nitric oxide (NO) breakdown and/or reduced bradykinin-mediated NO release. We investigated whether endothelial function was different between different ACE genotypes. We performed a cross-sectional study comparing the endothelial function of the 3 genotypes (II: n=25; ID: n=31; DD: n=12). Mean+/-SD ages of the subjects were 24+/-4 (II), 25+/-6 (ID), and 25+/-6 (DD) years. We assessed the impact of the genotypes on endothelial function and found that the DD genotype was associated with a significant blunting in endothelial-dependent vasodilatation (forearm blood flow data are presented as mean+/-SD ratio of blood flow in response to 3 incrementally increasing doses of each vasoactive agent in the test arm to blood flow in the control arm; the comparison is between DD versus ID versus II; the P value is an expression of an overall difference by ANOVA, and the 95% CIs are of a pairwise comparison between genotypes): acetylcholine, 2.88+/-1.45 versus 3.81+/-1.93 versus 4.23+/-2.37 (P=0.002; 95% CI [II versus ID], -0.19 to 0.91; 95% CI [II versus DD], 0.36 to 1.80; 95% CI [ID versus DD], 0.02 to 1.42). There was also a significant difference with the endothelial-independent vasodilator sodium nitroprusside, with values of 2.11+/-1.00 versus 2.55+/-1.36 versus 2.75+/-1.18 (P<0.05; 95% CI [II versus ID], -0.15 to 0.51; 95% CI [II versus DD], 0.03 to 0.89; 95% CI [ID versus DD], -0.13 to 0.71), but not with verapamil. There was no effect of the ACE genotype on endothelial-dependent or -independent vasoconstrictors NG-monomethyl-L-arginine or norepinephrine. Investigating the effects of cigarette smoking on each genotype demonstrated that for II and DD genotypes, acetylcholine responses were further blunted if subjects smoked. These data demonstrate that the DD ACE genotype in a young population is associated with a blunting of stimulated endothelial NO and donated NO responses but not to non-NO vasodilators or vasoconstrictors.

The Emerging Importance of Genetics in Epidemiologic Research III. Bioinformatics and statistical genetic methods

PURPOSE

To outline potential benefits of integrating recent developments in bioinformatics and statistical genetics with traditional epidemiologic studies to localize genes influencing complex phenotypes and examine genetic effects on disease susceptibility.

METHODS

An overview of bioinformatic and statistical approaches for localizing disease-susceptibility genes as well as challenges associated with identifying functional DNA variants and context-dependent genetic effects concludes this three-part series on the importance of genetics in epidemiologic research.

RESULTS

Rapidly evolving bioinformatic and statistical methods are providing invaluable information on newly-discovered genes and molecular variation influencing human diseases that is readily available to epidemiologic researchers.

CONCLUSIONS

Integrating bioinformatics and molecular biotechnology with epidemiologic methods of assessing disease risk is rapidly expanding our ability to identify genetic influences on complex human diseases. These technological advances are likely to have a profound impact on current knowledge of complex disease etiology, and may reveal novel approaches to disease treatment and prevention.

Coronary heart disease. At the interface of molecular genetics and preventive medicine

BACKGROUND

Susceptibility to common chronic diseases such as coronary heart disease (CHD) appears to be influenced by "context-dependent effects," which include interactions among genes (genetic epistasis) and among genes and environmental factors (gene-environment interactions).

METHODS

A synthesis of current knowledge and research findings demonstrates the importance of integrating genetic research on cardiovascular disease with preventive medicine and public health initiatives.

RESULTS

A variety of candidate genes have been implicated in risk for CHD, but only limited examples of context-dependent effects have been described. Interactions between genetic and environmental factors appear to influence lipid metabolism, plasma homocysteine levels, and pharmacologic response to many commonly prescribed medications. Quantification of genetic effects associated with increased disease risk that are modifiable by interventions such as diet, exercise, and smoking cessation is an important interface between molecular genetics and preventive medicine.

CONCLUSIONS

As a primary focus of preventive medicine expands to encompass early detection and treatment of asymptomatic individuals at risk for disease, the ability to quantify the influence of context-dependent effects on disease risk will be critical for determining drug safety and effectiveness in diverse patient populations and for implementing effective prevention and treatment programs.

Angiotensin converting enzyme gene polymorphisms and renal disease

In the past year there has been a profusion of reports identifying a possible association between the insertion/deletion polymorphism of the angiotensin converting enzyme and renal diseases. Rather than clarifying the situation, it has become more difficult to interpret its significance owing to small sample sizes and concerns over methodology; hence, studies are frequently contradictory. Despite these concerns there is evidence for a role of this polymorphism in progressive renal disease. This review summarizes the major studies in this field and suggests future strategies that might be employed to identify useful genetic markers in nephrology, for which the angiotensin converting enzyme polymorphism has acted as an important paradigm.