The angiotensin-I converting enzyme (ACE) gene I/D polymorphism and ACE levels in Pima Indians

The Gene Polymorphism of Angiotensin-Converting Enzyme Intron Deletion and Angiotensin-Converting Enzyme G2350A in Patients With Left Ventricular Hypertrophy: A Meta-analysis

Objectives

The aim of the study was to evaluate the correlation between left ventricular hypertrophy and the gene polymorphism of angiotensin-converting enzyme (ACE) intron deletion (I/D) and ACE G2350A.

Methods

Information related to the sample size and genotype frequencies was extracted from each study.

Results

Our results found that the D allele (p = 0.0180) and DD genotype (p = 0.0110) of ACE I/D had a significant association with increasing the risk of left ventricular hypertrophy, whereas the I allele (p = 0.0180), but not II (p = 0.1660) and ID genotypes (p = 0.1430), was associated with decreasing the risk of left ventricular hypertrophy. On other hand, we found that the A allele (p = 0.0020) and GA genotype of ACE G2350A (p = 0.0070) had the correlation with increasing the risk of left ventricular hypertrophy.

Conclusions

Our meta-analysis reveals that the D allele of ACE I/D and the A allele of ACE G2350A are associated with increasing the risk of left ventricular hypertrophy.

Effects of Interactions among Gene Polymorphisms of the Renin–Angiotensin-Aldosterone System on Hypertension in Turkish People from Southeast Anatolia

Introduction: Hypertension (HT) is characterized by high blood pressure. The reninangiotensin-aldosterone system (RAAS) plays a crucial role in blood pressure (BP) regulation by maintaining vascular tone and the water-sodium balance. We aimed to investigate whether there is any relation between AGT (M235T), ACE (I/D), and AGTR1 (A1166C) genetic polymorphisms and hypertension among Turkish people from Southeast Anatolia.

Method and Results: A total of 210 individuals, consisting of 102 healthy controls and 108 patients with essential hypertension admitted to the Cardiology Department of the Adıyaman University Research and Application Hospital were included the study. DNA isolation was performed from the blood samples via commercial kit. Genotype determination was determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Statistically significant differences were found between the control and patient groups in terms of genotype distribution and allelic frequencies of ACE I/D polymorphisms. Significant differences were found in the frequencies of ICM, DCM, DCT, DAT between the patient and control groups.

Conclusions: In this study, we found a significant association of ACE I/D polymorphism with HT, and we showed that the I allele can increase the risk of HT in Turkish people from Southeast Anatolia. Although we did not find any association between independent AGT M235T and AGT1R A1166C polymorphisms and HT, we observed that the DCM, DCT, and DAT haplotypes of ACE/AGT1R/AGT polymorphisms reduced the risk of hypertension, while the ICM haplotype increased it.

Genetic Predisposition to Diabetic Nephropathy: Evidence for a Role of ACE (I/D) Gene Polymorphism in Type 2 Diabetic Population from Kutch Region

Genetic polymorphism as described with angiotensin-converting enzyme gene has been proposed as a putative mediator of diabetic nephropathy. We substantiate the hypothesis that genetic variants of the ACE have significant impacts on diabetic nephropathy. To assess the possible association between the three ACE polymorphic variants and DN in an ethnically homogeneous type 2 diabetic population from Kutch region. A 287-bp insertion/deletion polymorphism in intron 16 of the ACE gene was examined by polymerase chain reaction using a case-control approach conducted with 309 unrelated type 2 diabetic patients of Kutch origin (159 Ahir and 150 Rabari, with >10 years duration of T2DM). Of the patients, 143 had nephropathy {AER >30 mg/day (Ahir, n:73 and Rabari, n:70)} and were considered as cases; all others {n:166 (86 Ahir and 80 Rabari)} were normoalbuminuric (AER <30 mg/day) and were treated as controls. Suitable descriptive statistics was used for different variables. Genotype frequencies in all groups were all in accordance with the Hardy-Weinberg equilibrium. Genotypic distribution was significantly different between cases and controls (Ahir: x(2) :8.87, 2 d.f. p = 0.0118; Rabari: x(2) :11.01, 2 d.f. p = 0.0041). Multivariate logistic regression analysis revealed that DD genotype was a significant and strongest independent predictor of microalbuminuria (Ahir: p = 0.0362, OR = 2.65, 95 % CI 1.89-6.36; Rabari: p = 0.024, OR = 2.81, 95 % CI 1.9-6.65). However, it did not independently change the odds of having macroalbuminuria versus microalbuminuria. Analysis of the association under various genetic models revealed that ACE I/D polymorphic variant contribute to DN susceptibility under recessive mode only. Genetic variation at the ACE locus as D/D variant in intron 16, contribute to an increased risk of nephropathy in T2DM patients but not extent of DN severity, and thus this polymorphism might be considered as genetic risk factors for DN among patients with type 2 diabetes.

Frequency of APOE, MTHFR and ACE polymorphisms in the Zambian population

Background

Polymorphisms within the apolipoprotein-E (APOE), Methylenetetrahydrofolate reductase (MTHFR) and Angiotensin I-converting enzyme (ACE) genes has been associated with cardiovascular and cerebrovascular disorders, Alzheimer’s disease and other complex diseases in various populations. The aim of the study was to analyze the allelic and genotypic frequencies of APOE, MTHFR C677T and ACE I/D gene polymorphisms in the Zambian population.

Results

The allele frequencies of APOE polymorphism in the Zambian populations were 13.8%, 59.5% and 26.7% for the ε2, ε3 and ε4 alleles respectively. MTHFR C677T and ACE I/D allele frequencies were 8.6% and 13.8% for the T and D minor alleles respectively. The ε2ε2 genotype and TT genotype were absent in the Zambian population. The genetic distances between Zambian and other African and non-African major populations revealed an independent variability of these polymorphisms.

Conclusion

We found that the APOE ε3 allele and the I allele of the ACE were significantly high in our study population while there were low frequencies observed for the MTHFR 677 T and ACE D alleles. Our analysis of the APOE, MTHFR and ACE polymorphisms may provide valuable insight into the understanding of the disease risk in the Zambian population.

A modern understanding of the traditional and nontraditional biological functions of angiotensin-converting enzyme

Angiotensin-converting enzyme (ACE) is a zinc-dependent peptidase responsible for converting angiotensin I into the vasoconstrictor angiotensin II. However, ACE is a relatively nonspecific peptidase that is capable of cleaving a wide range of substrates. Because of this, ACE and its peptide substrates and products affect many physiologic processes, including blood pressure control, hematopoiesis, reproduction, renal development, renal function, and the immune response. The defining feature of ACE is that it is composed of two homologous and independently catalytic domains, the result of an ancient gene duplication, and ACE-like genes are widely distributed in nature. The two ACE catalytic domains contribute to the wide substrate diversity of ACE and, by extension, the physiologic impact of the enzyme. Several studies suggest that the two catalytic domains have different biologic functions. Recently, the X-ray crystal structure of ACE has elucidated some of the structural differences between the two ACE domains. This is important now that ACE domain-specific inhibitors have been synthesized and characterized. Once widely available, these reagents will undoubtedly be powerful tools for probing the physiologic actions of each ACE domain. In turn, this knowledge should allow clinicians to envision new therapies for diseases not currently treated with ACE inhibitors.

Keeping pace with ACE: are ACE inhibitors and angiotensin II type 1 receptor antagonists potential doping agents?

In the decade since the angiotensin-converting enzyme (ACE) gene was first proposed to be a 'human gene for physical performance', there have been numerous studies examining the effects of ACE genotype on physical performance phenotypes such as aerobic capacity, muscle function, trainability, and athletic status. While the results are variable and sometimes inconsistent, and corroborating phenotypic data limited, carriers of the ACE 'insertion' allele (the presence of an alu repeat element in intron 16 of the gene) have been reported to have higher maximum oxygen uptake (VO2max), greater response to training, and increased muscle efficiency when compared with individuals carrying the 'deletion' allele (absence of the alu repeat). Furthermore, the insertion allele has been reported to be over-represented in elite athletes from a variety of populations representing a number of endurance sports. The mechanism by which the ACE insertion genotype could potentiate physical performance is unknown. The presence of the ACE insertion allele has been associated with lower ACE activity (ACEplasma) in number of studies, suggesting that individuals with an innate tendency to have lower ACE levels respond better to training and are at an advantage in endurance sporting events. This could be due to lower levels of angiotensin II (the vasoconstrictor converted to active form by ACE), higher levels of bradykinin (a vasodilator degraded by ACE) or some combination of the two phenotypes. Observations that individuals carrying the ACE insertion allele (and presumably lower ACEplasma) have an enhanced response to training or are over-represented amongst elite athletes raises the intriguing question: would individuals with artificially lowered ACEplasma have similar training or performance potential? As there are a number of drugs (i.e. ACE inhibitors and angiotensin II type 1 receptor antagonists [angiotensin receptor blockers--ARBs]) that have the ability to either reduce ACEplasma activity or block the action of angiotensin II, the question is relevant to the study of ergogenic agents and to the efforts to rid sports of 'doping'. This article discusses the possibility that ACE inhibitors and ARBs, by virtue of their effects on ACE or angiotensin II function, respectively, have performance-enhancing capabilities; it also reviews the data on the effects of these medications on VO2max, muscle composition and endurance capacity in patient and non-patient populations. We conclude that, while the direct evidence supporting the hypothesis that ACE-related medications are potential doping agents is not compelling, there are insufficient data on young, athletic populations to exclude the possibility, and there is ample, albeit indirect, support from genetic studies to suggest that they should be. Unfortunately, given the history of drug experimentation in athletes and the rapid appropriation of therapeutic agents into the doping arsenal, this indirect evidence, coupled with the availability of ACE-inhibiting and ACE-receptor blocking medications may be sufficiently tempting to unscrupulous competitors looking for a shortcut to the finish line.

Association of the insertion/deletion polymorphism of the angiotensin-converting enzyme gene with type 2 diabetes in two ethnic groups of Jerba Island in Tunisia

Introduction.The aim of the current study was to evaluate the role of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism on the prediction of type 2 diabetes in two ethnic populations from Jerba Island,Tunisia.

Methods. In this study, we analysed the genotypic and the allelic distributions of the ACE I/D polymorphism and conducted a case/control association study between healthy normoglycaemic controls and diabetic patients in the two studied groups.ACE gene polymorphism was analysed by polymerase chain reaction in 272 individuals consisting of 172 diabetic subjects and 100 controls.

Results.The genotype frequencies for DD, ID and II were 75.50%, 19.60% and 4.89% inArabs and 76.66%, 16.66% and 6.67% in Berbers, respectively, in the case group, and 42.85%, 35.71% and 21.43% inArabs and 57.50%, 22.50% and 20.00% in Berbers, respectively, in the control group.The DD frequency was significantly higher in the case group than in the control group (p<0.001), suggesting that the DD genotype is associated with an increased susceptibility to type 2 diabetes in our study populations.

Conclusions.The current investigation provides new evidence regarding the role of the ACE I/D polymorphism in the pathogenesis of type 2 diabetes in Jerbian populations. Furthermore, it underlines the importance of ethnicity, which should be considered in all studies aiming to test the genetic effects on the susceptibility to type 2 diabetes.

Diabetes and chronic kidney disease: lessons from the Pima Indians

Although diabetic nephropathy is a very rare cause of kidney failure during childhood, the underlying events leading to progressive kidney injury begin during childhood in many patients with type 1 diabetes mellitus (T1DM) and in increasing numbers of children with type 2 diabetes mellitus (T2DM). The Pima Indians of Arizona represent an exceptionally thoroughly studied population suffering from very high rates of T2DM and diabetic nephropathy (T2DN). This population well illustrates the often inexorable progression from glomerular hyperfiltration to microalbuminuria to overt proteinuria and loss of glomerular filtration rate (GFR), paralleled by the accumulation of mesangial matrix and basement membrane, glomerular hypertrophy, loss of podocytes and eventual glomerular sclerosis and interstitial fibrosis. Structural changes quantitatively account for the loss of GFR in T2DN. The mechanism of albuminuria (and its relationship to GFR loss) is much less clear. There is strong functional and structural evidence for defects in glomerular size-selectivity (shunts) due to podocyte pathology, but only beginning at relatively high levels of proteinuria (albumin/creatinine ratios > 3000 mg/g). Podocyte loss accompanies, and may underlie, the loss of glomeruli to sclerosis. At this point, most evidence in humans suggests detachment of intact podocytes from the glomerular basement membrane, rather than apoptosis, as the predominant mechanism of podocyte loss.

The impact of ACE genotype on serum ACE activity in a black South African male population

The strong association between the angiotensin I-converting enzyme (ACE) gene I/D polymorphism with serum ACE activity appears lacking in Nigerians and Kenyans, but has not previously been well assessed in others of African origin. This study addressed this issue in an ethnically well defined black South African population. A putative association for the A22982G ACE gene variant, a QTL likely to impact on serum ACE activity, was also sought. Subjects were 200 healthy male black South African volunteers from the Xhosa ethnic group. Venous blood was obtained from all subjects for DNA extraction. ACE I/D and A22982G genotypes were determined and serum ACE activity measured. Age and blood pressure were recorded. For the group as a whole (mean +/- SD age 38.5 +/- 9.8 years, SBP 119.6 +/- 14.1 mmHg, DBP 78.2 +/- 10.1 mmHg) serum ACE activity was 38.2 +/- 11.2 nmol ml(-1)min(-1). ACE I/D genotype was not significantly associated with serum ACE activity. In contrast, the A22982G variant was significantly associated with serum ACE activity, being 35.9 +/- 9.6, 38.1 +/- 10.6 and 42.4 +/- 15.3 nmol ml(-1)min(-1) for AA, AG and GG genotypes respectively; p = 0.03 by ANOVA and p = 0.01 by linear trend. In keeping with the findings in some other African populations, the ACE I/D polymorphism is not strongly associated with serum ACE activity in Xhosa South Africans. As such, it cannot be used as a marker of ACE activity in these subjects. In this regard the use of the A22982G gene variant may be more appropriate.

Angiotensin-I-converting enzyme (ACE) insertion/deletion polymorphism in Mexican patients with coronary artery disease. Association with the disease but not with lipid levels

Angiotensin-I-converting enzyme (ACE) insertion/deletion (ID) polymorphism has been associated with the genetic susceptibility to coronary artery disease (CAD) and also with the lipid profile in several populations. In the present work, we analyzed the distribution of ID polymorphism in 147 Mexican patients with CAD and 100 unrelated healthy controls. The correlation of this polymorphism with the lipid profile (cholesterol, low density lipoprotein-cholesterol, very low density lipoprotein-cholesterol, high density lipoprotein-cholesterol and triglycerides) in the patients group was determined. Increased frequency of D allele as well as DD genotype and decreased frequency of I allele and II genotype were found in CAD patients group (pC = 0.00058, OR = 1.96, pC = 0.021, OR = 2.5 and pC = 0.00058, OR = 0.51, pC = 0.0028, OR = 0.38). Correlation between ID genotypes and lipid profile in patients was carried out in total population and separately for females and males. After they had been adjusted for age, sex and BMI, there was no association among the three genotypes (II, ID and DD) and lipids and lipoproteins in none of the studied groups. Our data suggest that genetic variation at the ACE is a genetic factor related with the susceptibility to coronary artery disease in the Mexican Mestizo population.

Genetic determinants of blood pressure regulation

Hypertension is a multifactorial disorder that probably results from the inheritance of a number of susceptibility genes and involves multiple environmental determinants. Existing evidence suggests that the genetic contribution to blood pressure variation is about 30-50%. Although a number of candidate genes have been studied in different ethnic populations, results from genetic analysis are still inconsistent and specific causes of hypertension remain unclear. Furthermore, the abundance of data in the literature makes it difficult to piece together the puzzle of hypertension and to define candidate genes involved in the dynamic of blood pressure regulation. In this review, we attempt to highlight the genetic basis of hypertension pathogenesis, focusing on the most important existing genetic variations of candidate genes and their potential role in the development of this disease. Our objective is to review current knowledge and discuss limitations to clinical applications of genotypic information in the diagnosis, evaluation and treatment of hypertension. Finally, some principles of pharmacogenomics are presented here along with future perspectives of hypertension.

Modeling GFR trajectories in diabetic nephropathy

In an 8-year longitudinal study of Pima Indians with type 2 diabetes and nephropathy, we used statistical techniques that are novel and depend on minimal assumptions to compare longitudinal measurements of glomerular filtration rate (GFR). Individuals enrolled with new-onset microalbuminuria either progressed to macroalbuminuria (progressors, n = 13) or did not progress (nonprogressors, n = 13) during follow-up. Subjects with new-onset macroalbuminuria at screening were also followed (n = 22). Patients had their GFR determined serially by urinary iothalamate clearances (average 11 clearances; range 6-19). GFR courses of individuals were modeled using an adaptation of smoothing and regression cubic B-splines. Group comparisons were based on five-component vectors of fitted GFR values using a permutation approach to a Hotelling's T(2) statistic. GFR profiles of initially microalbuminuric progressors differed significantly from those of nonprogressors (P = 0.003). There were no significant baseline differences between progressors and nonprogressors with respect to any measured clinical parameters. The course of GFR in the first 4 yr following progression to macroalbuminuria in initially microalbuminuric subjects did not differ from that in newly screened macroalbuinuric subjects (P = 0.27). Without imposing simplifying models on the data, the statistical techniques used demonstrate that the courses of decline of GFR in definable subgroups of initially microalbuminuric diabetic Pima Indians, although generally progressive, follow distinct trajectories that are related to the extent of glomerular barrier dysfunction, as reflected by the evolution from microalbuminuria to macroalbuminuria.

Prevalence of eight molecular markers associated with thrombotic diseases in six Amerindian tribes and two African groups of Costa Rica

Individuals belonging to six different Amerindian tribes and two African groups of Costa Rica were genotyped for factor V Leiden (FV), factor V haplotype HR2 (FV HR2), Factor II 20210G>A (FII), the methylenetetrahydrofolate reductase (MTHFR), factor VII polymorphisms (FVII IVS7, FVII R353Q), factor XIII (FXIII V34L), and the insertion/deletion (I/D) polymorphism of the gene of angiotensin converting enzyme (ACE). Clear differences in the prevalence were found and are first reported. The prevalence of some of the established genetic risk factors was low in Amerindians of Costa Rica (ACE) or even absent (FVL, FII), and others (MTHFR, FVHR2) had an extremely high prevalence. People of African origin carried very rare FVL or FII polymorphisms, but the DD genotype of ACE is the highest reported. Concerning the protective factors, the QQ genotype of FVII R353Q was absent in Amerindians, but the protective 7/7 genotype of FVII IVS7 frequently found. Novel alleles of FVII IVS7 (4, 8, and 9 monomers) were found. Intertribal heterogeneity was observed that may reflect the evolutionary history of these tribal groups and their admixture with other populations.

Angiotensin-converting enzyme and genetics at high altitude

As part of the renin-angiotensin system (RAS), angiotensin-converting enzyme (ACE) plays a key role in circulatory homeostasis. ACE degrades vasodilator kinins and generates angiotensin II. A polymorphism in intron 16 of the human ACE gene has been identified in which the presence (insertion, I allele) rather than the absence (deletion, D allele) of a 287 bp fragment is associated with lower serum and tissue ACE activity. The I allele has been associated with some aspects of endurance performance, being found with excess frequency in elite distance runners, rowers, and other elite athletes. Mountaineers also demonstrate an allele skew with a significant excess of the I allele and II genotype in elite, male, British mountaineers who have ascended beyond 7000 m without the use of supplemental oxygen. This review evaluates the evidence for and against an association of the I allele with human endurance, and performance at high altitude. We conclude that the I allele does confer an advantage, most likely mediated via improved muscle efficiency with secondary benefits in terms of conservation of non-fat mass.

Angiotensin-converting enzyme ID polymorphism and fitness phenotype in the HERITAGE Family Study

It has been suggested that genetic variation in the angiotensin-converting enzyme (ACE) gene is associated with physical performance. We studied the association between the ACE insertion (I)/deletion (D) polymorphism and several fitness phenotypes measured before and after 20 wk of a standardized endurance training program in sedentary Caucasian (n = 476) and black (n = 248) subjects. Phenotypes measured were oxygen uptake (VO(2)), work rate, heart rate, minute ventilation, tidal volume, and blood lactate levels during maximal and submaximal [50 W and at 60 and 80% of maximal VO(2) (VO(2 max))] exercise and stroke volume and cardiac output during submaximal exercise (50 W and at 60% VO(2 max)). The ACE ID polymorphism was typed with the three-primer PCR method. Out of 216 association tests performed on 54 phenotypes in 4 groups of participants, only 11 showed significant (P values from 0.042 to 0. 0001) associations with the ACE ID polymorphism. In contrast to previous claims, in Caucasian offspring, the DD homozygotes showed a 14-38% greater increase with training in VO(2 max), VO(2) at 80% of VO(2 max), and all work rate phenotypes and a 36% greater decrease in heart rate at 50 W than did the II homozygotes. No associations were evident in Caucasian parents or black parents or offspring. Thus these data do not support the hypothesis that the ACE ID polymorphism plays a major role in cardiorespiratory endurance.

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.

Angiotensin-1-converting enzyme (ACE) gene polymorphism, plasma ACE levels, and their association with the metabolic syndrome and electrocardiographic coronary artery disease in Pima Indians

In Caucasian subjects, an insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with coronary artery disease (CAD) and fatal myocardial infarction. The underlying mechanism(s) of this association is not fully understood. Pima Indians have a low incidence of nonfatal and fatal CAD despite a high prevalence of diabetes. In Pima Indians, circulating ACE levels are related to ACE genotype, but the frequency of the D allele is significantly lower than in Caucasians. A lower frequency of the D allele may underlie a low risk of CAD in this population. We examined the relationship of the ACE genotype and plasma ACE level with electrocardiographic evidence of CAD (Tecumseh criteria), hypertension, and metabolic variables associated with insulin resistance in 305 (146 men and 159 women aged 47+/-9.0 years) Pima Indians characterized for the ACE I/D genotype. The distribution of ACE genotypes was unrelated to diabetes and obesity. Fasting plasma insulin, plasminogen activator inhibitor-1 (PAI-1) activity, plasma triglyceride concentrations, and systolic (SBP) and diastolic (DBP) blood pressure were not significantly different between the three ACE genotypes among nondiabetic and diabetic subjects. There was no significant association of ACE genotype with electrocardiographic evidence of CAD or with hypertension. Plasma ACE concentrations were not significantly different between nondiabetic and diabetic subjects (median, 77 [range, 21 to 1691 v 83 [7 to 238] IU/mL, P=NS). In all subjects, plasma ACE levels were associated weakly with plasma triglyceride (partial r=.20, P < .01) and total cholesterol (partial r=.13, P <.03) concentrations, but not with fasting plasma insulin or PAI-1 activity. In diabetic subjects, ACE levels were related to fasting plasma glucose concentrations (partial r=.15, P=.07). These findings would suggest that ACE gene I/D polymorphism is unlikely to be a major determinant of susceptibility to CAD in Pima Indians. Plasma ACE levels, but not ACE genotype, correlated with lipids, plasma glucose, and blood pressure, suggesting that elevated plasma ACE levels may contribute to the link between insulin resistance and CAD disease or may be a consequence of it.

The angiotensin-converting enzyme (ACE) gene insertion/deletion dimorphism tracks with higher serum ace activities in both younger and older subjects

BACKGROUND

The absence of a 287 base pair alu sequence in the ACE gene (D allele) is associated with higher ACE levels than its presence (I allele) in adults. We carried out a case-control study of the ACE*I/D dimorphism in relation to circulating ACE activities to evaluate associations between the two variables in adults, compared to younger (18 years or less) individuals.

MATERIALS AND METHODS

Genotypes of the ACE*I/D dimorphism were determined on DNA samples from a population of 164 random (unrelated) Emirate nationals, composed of two groups: 112 subjects above 18 years of age (range=20-77 years), and 52 subjects of 18 years or less (range=1-18), and analyzed for putative associations with serum ACE activities. ACE*I/D genotypes of the 164 individuals were determined by assays based on polymerase chain reaction. ACE activities were determined on serum samples of these subjects by colorimetric assays.

RESULTS

The D allele was associated with increased ACE values in both adult and younger individuals. Mean ACE activity levels associated with II, ID and DD genotypes, however, were 42%-61% higher in the 18 years and under group of subjects. The ACE*I/D marker accounted for 28% of the variance of the phenomenon determining ACE levels in adults, and for 30% among youngsters.

CONCLUSION

The ACE*I/D dimorphism correlated strongly with circulating ACE activities in both adult and young Emirati subjects, and the corresponding mean ACE activities were significantly higher among the youngsters.