Does angiotensin-converting enzyme gene polymorphism affect blood pressure? Findings after 6 years of follow-up in healthy subjects

Association Between Hypertension, Dipping Status, and ACE and AGTR1 Gene Polymorphisms in Adolescents with Type 1 Diabetes

Objectives: This study aims to show the distribution of angiotensin-converting enzyme (ACE) rs1799752 (I>D) gene insertion/deletion (I/D) polymorphism and angiotensin II receptor type 1 (AGTR1) rs5186 (A>C) gene polymorphism in adolescents with hypertension (HT) and type 1 diabetes (T1D), as well as its association with hypertension and the diurnal variation of mean blood pressure (dipping phenomenon). Methods: A cross-sectional study was conducted involving 118 adolescents diagnosed with T1D who underwent clinical and laboratory investigations, genetic analyses, and 24 h ambulatory blood pressure monitoring. The genotype frequencies were compared between adolescents with HT and those with normal blood pressure. Additionally, the genotype frequencies were compared between dippers and non-dippers. Results: Patients with HT were more likely to be female and exhibited significantly poorer glycemic control and higher triglycerides, along with increased body mass index and daily insulin dosage. The prevalence of ACE rs1799752 genotypes in the hypertensive group was 20% II, 66.7% ID, and 13.3% DD, which did not significantly differ from the normal blood pressure group with 29.1% II, 53.4% ID, and 17.5% DD (p = 0.625). The prevalence of AGTR1 rs5186 genotypes in the hypertensive group was 53.3% AC, 40% AA, and 6.7% CC, which also did not significantly differ from the normal blood pressure group with 39.8% AC, 52.4% AA, and 7.8% CC (p = 0.608). A total of 46% of the patients exhibited non-dipping phenomena. The prevalence of non-dippers among the ACE genotypes was 13% DD, 33.3% II, and 53.7% ID (p = 0.369), while for the AGTR1 genotypes, it was 50% AA, 42.6% AC, and 7.4% CC (p = 0.976). Conclusions: Our results indicate that in our adolescents with T1D, clinical and metabolic factors such as higher body mass index, triglycerides, suboptimal glycemic control, and female gender are more indicative of the development of hypertension than ACE and AGTR1 gene polymorphisms. A potential reason for this finding could be the young age of the patients or the relatively small size of the study group. Future research involving larger sample sizes is needed to further investigate the genetic predisposition for the development of hypertension.

The D allele of angiotensin-converting enzyme gene is associated with a worse autonomic heart control in community-based older adults

The relationship between the Renin-Angiotensin-Aldosterone System (RAAS) and modulation of the Autonomic Nervous System (ANS) is reported as complex and bidirectional. Thus, the present study aimed to compare autonomous heart control, through symbolic analysis parameters, in the older adults carrying different ACE I/D gene polymorphisms (rs4646994). Two hundred four older adults comprised the study population and were grouped according to the ACE I/D gene polymorphism: II + ID genotype and DD genotype. Successive RR intervals were recorded along 5 min and analyzed with Symbolic Analysis (SA) method. 0 V%, 1 V% and 2 V% patterns were quantified and compared between groups. A linear mixed model analysis was used to determine between-group differences in symbolic analysis parameters (0 V%, 1 V% and 2 V%), taken groups as fixed factor and sex, use of ACE inhibitors and Angiotensin II receptor type I blockers as random factors. The Bayesian analysis was carried out to check the magnitude of the evidence. The results of this study indicate that older adults carrying the DD genotype have statistically greater sympathetic modulation (0 V%) and poor sympathovagal balance (1 V%), but the Bayesian analysis indicate only an anecdotal effect. Sympathetic predominance is recognized a worrying condition, since may predisposes to cardiovascular risk.

Is diet partly responsible for differences in COVID-19 death rates between and within countries?

Reported COVID-19 deaths in Germany are relatively low as compared to many European countries. Among the several explanations proposed, an early and large testing of the population was put forward. Most current debates on COVID-19 focus on the differences among countries, but little attention has been given to regional differences and diet. The low-death rate European countries (e.g. Austria, Baltic States, Czech Republic, Finland, Norway, Poland, Slovakia) have used different quarantine and/or confinement times and methods and none have performed as many early tests as Germany. Among other factors that may be significant are the dietary habits. It seems that some foods largely used in these countries may reduce angiotensin-converting enzyme activity or are anti-oxidants. Among the many possible areas of research, it might be important to understand diet and angiotensin-converting enzyme-2 (ACE2) levels in populations with different COVID-19 death rates since dietary interventions may be of great benefit.

Ethnic differences in the association between angiotensin-converting enzyme gene insertion/deletion polymorphism and peripheral vascular disease: A meta-analysis

Background

Several studies have investigated the association of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism with peripheral vascular disease (PVD); however, the results remain controversial. Therefore, we conducted the current meta-analysis to evaluate this relationship in the general population of different ethnicities.

Methods

We searched PubMed, Embase, Web of Science, Wanfang Database, and CNKI to identify eligible studies. Random-effect models were applied to estimate the pooled odds ratio (OR) with a 95% confidence interval (CI), regardless of between-study heterogeneity.

Results

A total of 13 studies with 1966 cases and 6129 controls were included in this meta-analysis. The pooled ORs for the association between ACE I/D polymorphism and PVD risk were not statistically significant in the overall population under all genetic models. In further ethnicity-stratified analyses, we found a statistically significant association of ACE I/D polymorphism with PVD susceptibility in Asians under most models. However, the association among Caucasians did not reach statistical significance.

Conclusion

ACE I/D polymorphism might be associated with susceptibility to PVD in the Asian population, but there was no clear evidence indicating a similar significant relationship among Caucasians.

Renin-angiotensin system gene polymorphisms and high blood pressure in Lithuanian children and adolescents

Background

Epidemiological studies have demonstrated the influence of environmental factors on HBP in the population of Lithuanian children, although the role of genetic factors in hypertension has not yet been studied. The aim of this study was to assess the distribution of AGTR1, AGT, and ACE genotypes in the Lithuanian child population and to determine whether these genotypes have an impact on HBP in childhood.

Methods

This cross-sectional study enrolled 709 participants aged 12–15 years. The subjects were genotyped for AGT (M235 T, rs699), AGTR1 (A1166C, rs5186), and ACE (rs4340) gene polymorphisms using real-time and conventional polymerase chain reactions. Blood pressure and anthropometric parameters were measured.

Results

The prevalence of HBP was 38.6% and was more frequently detected in boys than in girls (47.9% vs. 29.5%; p < 0.001). No significant differences in the frequencies of the AGT or AGTR1 genotypes or alleles between boys and girls were observed, except for ACE genotypes. The mean SBP value was higher in HBP subjects with ACE ID genotype compared to those with ACE II homozygotes (p = 0.04). No significant differences in BP between different AGT and AGTR1 genotype groups were found. Boys who carried the ACE ID + DD genotypes had higher odds of having HBP than carriers of the ACE II genotype did (controlling for the body mass index (BMI): OR_MH = 1.83; 95% CI, 1.11–3.02, p = 0.024; and controlling for waist circumference (WC): OR_MH = 1.76; 95% CI, 1.07–2.92, p = 0.035). These associations were not significant among girls. The same trend was observed in the multivariate analysis – after adjustment for BMI and WC, only boys with ACE ID genotype and ACE ID + DD genotypes had statistically significantly increased odds of HBP (aOR = 2.05; 95% CI, 1.19–3.53 (p = 0.01) and aOR = 1.82; 95% CI, 1.09–3.04 (p = 0.022), respectively).

Conclusions

The evaluated polymorphisms of the AGT and AGTR1 genes did not contribute to the presence of HBP in the present study and may be seen as predisposing factors, while ACE ID genotypes were associated with significantly increased odds for the development of HBP in the Lithuanian child and adolescent population - especially in boys.

The High Blood Pressure-Malaria Protection Hypothesis

RATIONALE

A recently proposed hypothesis states that malaria may contribute to hypertension in endemic areas,¹ but the role of angiotensin II (Ang II), a major regulator of blood pressure, was not considered. Elevated levels of Ang II may confer protection against malaria morbidity and mortality, providing an alternative explanation for hypertension in malaria endemic areas.

OBJECTIVE

To discuss a possible alternative cause for hypertension in populations who have been under the selective pressure of malaria.

METHODS AND RESULTS

We reviewed published scientific literature for studies that could establish a link between Ang II and malaria. Both genetic and functional studies suggested that high levels of Ang II may confer protection against cerebral malaria by strengthening the integrity of the endothelial brain barrier. We also describe strong experimental evidence supporting our hypothesis through genetic, functional, and interventional studies.

CONCLUSIONS

A causal association between high levels of Ang II and protection from malaria pathogenesis can provide a likely explanation for the increased prevalence in hypertension observed in populations of African and South Asian origin. Furthermore, this potential causative connection might also direct unique approaches for the effective treatment of cerebral malaria.

Gene Polymorphisms of Angiotensin II Type 1 Receptor and Angiotensin-Converting Enzyme in Two Ethnic Groups Living in Zhejiang Province, China

Polymorphisms of ACE insertion/deletion (I/D) and angiotensin II type 1 receptor (AT1R) 1166A-C have been associated with many diseases, and distributions of their genotypes vary in different races and populations. The aim of this study was to investigate distributions of angiotensin-converting enzyme (ACE) and AT1R genotypes in Han and She populations in ZheJiang province. We determined ACE and AT1R genotypes in 189 Han and 163 She individuals. DNA was extracted from peripheral blood samples. Analyses of ACE and AT 1R genotypes were performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The frequencies of ACE genotypes and alleles among the Han sample (41.3%II, 41.3%ID, 17.5%DD; 61.9%I allele, 38.1%D allele) were similar to those among She individuals (39.9%II, 39.3%ID, 20.9%DD; 59.5%I allele, 40.5%D allele), with p=0.660; p=0.421. However, significant differences in the distributions of ACE polymorphism between men and women among She population were observed, with p=0.042, p=0.014. AT1R genotype and allele frequencies in the Han population were (88.4%AA, 11.1%AC, 0.5%CC) and (93.9%A allele, 6.1%C) allele respectively. In the She population they were (78.0%AA, 21.3%AC, 0.6%CC) and (89.0%A allele, 11.0%C allele). The significant differences were found between Han and She populations with p=0.031, p=0.018, and within subgroups of women, with p=0.010, p=0.021. There were no significant differences within subgroups of men (p=0.476, p=0.261). The genotype distributions or allele frequencies of ACE and AT1R were significantly different between the samples of the She and Han populations.

Does angiotensin-converting enzyme-1 (ACE-1) gene polymorphism lead to chronic kidney disease among hypertensive patients?

BACKGROUND

Hypertension is one of the important contributing factors linked with both causation and development of kidney disease. It is a multifactorial, polygenic, and complex disorder due to interaction of several risk genes with environmental factors. The present study was aimed to explore genetic polymorphism in ACE-1 gene as a risk factor for CKD among hypertensive patients.

METHODS

Three hundred patients were enrolled in the study. Ninety were hypertensive patients with CKD taken as cases, whereas 210 hypertensive patients without CKD were taken as controls. Demographic data including age, sex, Body mass index (BMI), and other risk factors were also recorded. DNA was extracted from blood by salting out method. Genotyping of ACE gene was done by PCR technique. All the statistical analysis was done by using Epi Info and SPSS version 16 software (SPSS Inc., Chicago, IL).

RESULTS

Mean age was higher in the control group (p < 0.05). Variables among two groups were compared out of which age, BMI, hemoglobin (Hb) was found to be statistically significant whereas other variables like systolic blood pressure, triglyceride and low-density lipoprotein were not. Blood urea and serum creatinine levels were statistically significant in the two genotypes (p < 0.05). Total and HDL cholesterol were statistically significant for DD genotype of ACE gene (OR = 1.42, 95% CI = 0.72-2.81). Similarly, the risk for CKD among hypertensive patients was also associated with D allele of ACE gene (OR = 1.25, 95% CI = 0.86-1.79).

CONCLUSION

It is concluded that ACE-DD genotype may be a risk factor for the causation and development of chronic kidney failure among hypertensive patients.

High Incidence of ACE/PAI-1 in Association to a Spectrum of Other Polymorphic Cardiovascular Genes Involving PBMCs Proinflammatory Cytokines in Hypertensive Hypercholesterolemic Patients: Reversibility with a Combination of ACE Inhibitor and Statin

Cardiovascular diseases (CVDs) are significantly high in the Lebanese population with the two most predominant forms being atherosclerosis and venous thrombosis. The purpose of our study was to assess the association of a spectrum of CVD related genes and combined state of hypertension hypercholesterolemia (HH) in unrelated Lebanese. Twelve polymorphisms were studied by multiplex PCR and reverse hybridization of DNA from 171 healthy individuals and 144 HH subjects. Two genes were significantly associated with HH: ACE (OR: 9.20, P<0.0001) and PAI-1 (OR: 2.29, P = 0.007), respectively with the occurrence of the risky alleles “Del” and “4G”. The frequencies of the Del and 4G alleles were found to be 0.98 and 0.90 in the HH group versus 0.84 and 0.79 in the healthy group, respectively. Serum ACE activity and PAI-I increased significantly with Del/Del and 4G/5G genotypes. The co-expression of Del/4G(+/+) was detected in 113 out of 171 (66.0%) controls and 125 out of 144 (86.8%) HH subjects. Del/4G(-/-) was detected in only 6 (3.5%) controls and undetected in the HH group. Three venous thrombosis related genes [FV(Leiden), MTHFR(A1298C) and FXIII(V34L)] were significantly related to the prominence of the co-expression of Del/4G(+/+). A range of 2 to 8 combined polymorphisms co-expressed per subject where 5 mutations were the most detected. In Del/4G(+/+) subjects, peripheral blood mononuclear cells (PBMCs) produced significant elevated levels of IFN-γ and TNF-α contrary to IL-10, and no variations occurred for IL-4. ACE inhibitor (ramipril) in combination with statin (atorvastatin) and not alone reversed significantly the situation. This first report from Lebanon sheds light on an additional genetic predisposition of a complex spectrum of genes involved in CVD and suggests that the most requested gene FVL by physicians may not be sufficient to diagnose eventual future problems that can occur in the cardiovascular system. Subjects expressing the double mutations (Del/4G) are at high risk for the onset of CVDs.

Cathepsin K analysis in a pycnodysostosis cohort: demographic, genotypic and phenotypic features

Background

To characterize cathepsin K (CTSK) mutations in a group of patients with pycnodysostosis, who presented with either short stature or atypical fractures to pediatric endocrinology or dysmorphic features to pediatric genetics clinics.

Methods

Seven exons and exon/intron boundaries of CTSK gene for the children and their families were amplified with PCR and sequenced. Sixteen patients from 14 families with pycnodysostosis, presenting with typical dysmorphic features, short stature, frequent fractures and osteosclerosis, were included in the study.

Results

We identified five missense mutations (M1I, I249T, L7P, D80Y and D169N), one nonsense mutation (R312X) and one 301 bp insertion in intron 7, which is revealed as Alu sequence; among them, only L7P and I249 were described previously. The mutations were homozygous in all cases, and the families mostly originated from the region where consanguineous marriage rate is the highest. Patients with M1I mutation had fractures, at younger ages than the other pycnodysostosis cases in our cohort which were most probably related to the severity of mutation, since M1I initiates the translation, and mutation might lead to the complete absence of the protein. The typical finding of pycnodysostosis, acroosteolysis, could not be detected in two patients, although other patients carrying the same mutations had acroosteolysis. Additionally, none of the previously described hot spot mutations were seen in our cohort; indeed, L7P and R312X were the most frequently detected mutations.

Conclusions

We described a large cohort of pycnodysostosis patients with genetic and phenotypic features, and, first Alu sequence insertion in pycnodysostosis.

Angiotensin converting enzyme insertion/deletion polymorphism is associated with increased adiposity and blood pressure in obese children and adolescents

BACKGROUND

The insertion/deletion polymorphism in the gene encoding the angiotensin-converting enzyme (ACE I/D) was associated with arterial hypertension and obesity in adults, but the data in children are scarce and yielded contrasting results. We assessed the impact of the ACE I/D on blood pressure and obesity related traits in a Brazilian cohort of obese children and adolescents.

METHODS AND RESULTS

ACE I/D was genotyped in 320 obese children and adolescents (64% of girls) aged 7-16years, referred for a weight-loss program. We observed an association of the D-allele with blood pressure and with pre-hypertension/hypertension in boys (odds ratio 2.44, 95% C.I. 1.34-4.68, p=0.005 for a codominant model). The D-allele, insulin resistance and body fat mass had independent and additive effects and explained 14% of the variance of pre-hypertension/hypertension. The BMI, waist circumference, and body fat mass were significantly higher in DD/ID boys than in II boys (p<0.005). Allelic associations with obesity related traits were independent of the association with blood pressure. No genotype associations were observed in girls.

CONCLUSIONS

The D-allele of the ACE I/D polymorphism was associated with arterial hypertension and with obesity related traits in boys, but not in girls, in a cohort of obese children and adolescents. These associations were independent of each other, as well as of the effects of other confounding traits such as insulin secretion, insulin sensitivity and glucose tolerance. Our results are in agreement with experimental evidences suggesting that the renin-angiotensin system plays a role in the regulation of visceral adipose tissue accumulation.

Acute and chronic effects of resistance exercise on blood pressure in elderly women and the possible influence of ACE I/D polymorphism

This study investigated the chronic effect of blood pressure (BP) and post-exercise hypotension (PEH) during resistance training (RT) and its relation with the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in hypertensive elderly women. Participants were divided into two groups: an experimental group (EG) with exercise and a control group (CG) without exercise. The EG performed one adaptation month and one repetition maximum load (1RM) test at the end of this period. After the first month, the EG conducted a three-month program of RT at 60%, 70%, and 80% of 1RM, respectively, for each month. The CG was evaluated at the end of each month. Systolic (SBP) and diastolic (DBP) blood pressure (Microlife BP 3AC1-1) were measured, with the subject in a seated position, during an acute session for both GE and CG as follows: every 5 minutes for 20 minutes at pre-exercise rest, immediately after the resistance exercise and control, and every 15 minutes during 1 hour of recovery after exercise and CG. Analysis of covariance showed reduction in SBP and DBP (P ≤ 0.05) rest values after the RT program. PEH was observed only for the EG in acute sessions, for SBP after the second and third months (P ≤ 0.05), and for DBP after the second and fourth months (P ≤ 0.05). No significant differences in main effects and interaction effects between blood pressure and ACE I/D were observed. The occurrence of chronic reduction of blood pressure and PEH through EG may have a protective effect on the cardiovascular system with no ACE I/D polymorphism influence for this population.

Characterization of the relationship between APOBEC3B deletion and ACE Alu insertion

The insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE), commonly associated with many diseases, is believed to have affected human adaptation to environmental changes during the out-of-Africa expansion. APOBEC3B (A3B), a member of the cytidine deaminase family APOBEC3s, also exhibits a variable gene insertion/deletion polymorphism across world populations. Using data available from published reports, we examined the global geographic distribution of ACE and A3B genotypes. In tracking the modern human dispersal routes of these two genes, we found that the variation trends of the two I/D polymorphisms were directly correlated. We observed that the frequencies of ACE insertion and A3B deletion rose in parallel along the expansion route. To investigate the presence of a correlation between the two polymorphisms and the effect of their interaction on human health, we analyzed 1199 unrelated Chinese adults to determine their genotypes and other important clinical characteristics. We discovered a significant difference between the ACE genotype/allele distribution in the A3B DD and A3B II/ID groups (P = 0.045 and 0.015, respectively), indicating that the ACE Alu I allele frequency in the former group was higher than in the latter group. No specific clinical phenotype could be associated with the interaction between the ACE and A3B I/D polymorphisms. A3B has been identified as a powerful inhibitor of Alu retrotransposition, and primate A3 genes have undergone strong positive selection (and expansion) for restricting the mobility of endogenous retrotransposons during evolution. Based on these findings, we suggest that the ACE Alu insertion was enabled (facilitated) by the A3B deletion and that functional loss of A3B provided an opportunity for enhanced human adaptability and survival in response to the environmental and climate challenges arising during the migration from Africa.

Angiotensin-converting enzyme deletion allele is beneficial for the longevity of Europeans

The human angiotensin converting enzyme (ACE) gene is one of the most investigated candidate genes for cardiovascular diseases (CVD), but the understanding of its role among the elderly is vague. Therefore, this study focuses at: (a) testing the association of ACE polymorphism with CVD risk factors among the elderly, and (b) detecting the possible unequal distribution of ACE genotypes between senescent and younger segments of the European populations. The association of ACE I/D polymorphism with CVD health status [hypertension (HT), obesity, dislypidemia] in 301 very old subjects (88.2 ± 5 years; F/M = 221/80) was tested by means of logistic regression analysis. The meta-analysis of D allele frequency in general vs. elderly (80+ years) groups was conducted using all publicly available data for European populations comprising both age cohorts. Multiple multinomial logistic regression revealed that within this elderly sample, age (younger olds, 80-90 years), female sex (OR = 3.13, 95% CI = 1.59-6.19), and elevated triglycerides (OR = 2.53, 95% CI = 1.29-4.95) were positively associated with HT, while ACE polymorphism was not. It was also established that the DD genotype was twice as high in 80+ cohort compared to general population of Croatia (p < 0.00001). This trend was confirmed by the meta-analysis that showed higher D allele frequencies in olds from nine of ten considered European populations (OR = 1.19, 95% CI = 1.08-1.31). The data in elderly cohort do not confirm previously reported role of ACE DD genotype to the development of HT. Moreover, meta-analysis indicated that ACE D allele has some selective advantage that contributes to longevity in majority of European populations.

The association of hypertension with renin-angiotensin system gene polymorphisms in the Lebanese population

AIM

The study objective was to examine the association of hypertension in the Lebanese population with three renin-angiotensin system gene polymorphisms (RAS): angiotensin-converting enzyme (ACE), angiotensinogen (AGT) and angiotensin-receptor type 1 (AT1R).

METHODS

A total of 270 subjects (124 hypertensive vs 146 normotensive) were genotyped for ACE insertion (I)/deletion (D), AGT (M235T), and AT(1)R (A1166C) gene polymorphisms by polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

The studied genes showed no deviation from Hardy-Weinberg equilibrium. No association could be reported with the ACE I/D polymorphism, although the D allele frequency was high (77%) in patients. AGT TT genotype prevalence was found to be lower in hypertensive versus normotensive subjects (p<0.0001). AT(1)R CC and AC genotypes were significantly more frequent in hypertensive than normotensive subjects (p<0.0001).

CONCLUSION

The first conducted study on the RAS gene polymorphisms in Lebanese hypertensive patients demonstrated a possible association of the AGT T and AT(1)R C alleles with hypertension.

Cross-sectional study of risk factors for atherosclerosis in the Azorean population

BACKGROUND

Atherosclerosis-a major cause of vascular disease, including ischemic heart disease (IHD), is a pathology that has a two-fold higher mortality rate in the Azorean Islands compared to mainland Portugal.

AIM

This cross-sectional study investigated the role of genetic variation in the prevalence of atherosclerosis in this population.

SUBJECTS AND METHODS

A total of 305 individuals were characterized for polymorphisms in eight susceptibility genes for atherosclerosis: ACE, PAI1, NOS3, LTA, FGB, ITGB3, PON1 and APOE. Data were analysed with respect to phenotypic characteristics such as blood pressure, lipid profile, life-style risk factors and familial history of myocardial infarction.

RESULTS

In the total sample, frequencies for hypercholestrolemic, hypertensive and obese individuals were 63.6%, 39.3% and 23.3%, respectively. The genetic profile was similar to that observed in other European populations, namely in mainland Portugal. No over-representation of risk alleles was evidenced in this sample.

CONCLUSIONS

One has to consider the possibility of an important non-genetic influence on the high cholesterolemia present in the Azorean population. Since diet is the most important life-style risk factor for dyslipidemia, studies aiming to evaluate the dietary characteristics of this population and its impact on serum lipid levels will be of major importance.

Relationship between ACE-DD polymorphism and diastolic performance in healthy subjects

BACKGROUND

The ACE-D allele has been associated with cardiovascular disease. The study evaluates the relationship between the ACE-ID genotypes and diastolic function in healthy subjects after 6 years of follow-up.

METHODS

Two hundred and seventy-five healthy volunteers aged 25-55 years had normal physical examination, 12-lead ECG, acceptable echocardiographic windows and echocardiogram at entry. Venous blood was drawn for DNA analysis.

RESULTS

Two hundred and forty-two subjects completed 6 years of follow-up. Three genetically distinct groups were obtained: ACE-DD group (n=71, 26F/45M, mean age 48 +/- 7 years); ACE-ID (n=115, 39F/76M, mean age 40 +/- 7 years); and ACE-II (n=56, 20F/36M, mean age 47 +/- 6 years). Significant differences in E/A ratio were found between ACE-DD and ACE-ID, and ACE II (p=0.028, <0.0001, 0.0001), respectively. After 6 years, echocardiography showed a significant reduction of E/A ratio in the ACE-DD group, p=0.0001.

CONCLUSION

The data suggest that ACE-DD is associated with deteriorating myocardial diastolic properties.

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

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

Association of renin-angiotensin system and natriuretic peptide receptor A gene polymorphisms with hypertension in a Hellenic population

Introduction. Hypertension results from the interaction of genetic and environmental factors. Since the renin-angiotensin and the natriuretic peptide systems contribute to blood pressure regulation, variations in the relative genes are candidates for the development of hypertension.

Materials and methods. In 194 hypertensives and 304 controls of Hellenic origin, the possible association between the (CA)n repeat polymorphism of angiotensinogen (AGT), the 250 bp insertion/deletion (I/D) of angiotensin-converting enzyme (ACE), the tetranucleotide repeat polymorphism (TCTG)n of renin, and the (CT)n repeat polymorphism of the natriuretic peptide receptor A (NPRA) and hypertension was assessed.

Results. No association between AGT and NPRA polymorphisms and hypertension was observed. The presence of ID or DD genotype of ACE was associated with an increased risk for hypertension compared with the II genotype (OR: 1.782 [95% CI: 1.032—3.077]), whereas the LL genotype of the renin gene was associated with a decreased risk compared with the SS genotype (OR: 0.174 [95% CI: 0.044—0.689]). However, after adjustment for confounding factors only the latter association remained.

Conclusions. In the present study conducted in a homogeneous Hellenic population, no associations betweenAGT,ACE, and NPRA gene polymorphisms and hypertension were found. The presence of a significant negative association between the LL polymorphism of the renin gene and hypertension requires further confirmation.

Angiotensin-converting enzyme polymorphisms and risk of spontaneous deep intracranial hemorrhage in Taiwan

BACKGROUND AND PURPOSE

This study examines whether angiotensin-converting enzyme (ACE) gene polymorphisms are associated with the risk of spontaneous deep intracerebral hemorrhage (SDICH) in Taiwan using a case-control study.

METHODS

Totally, 217 SDICH patients and 283 controls were recruited. Associations of ACE A-240T and ACE I/D polymorphisms with SDICH were examined under the additive model and adjusted for gender, age, body mass index, total cholesterol level, smoking history, alcohol use, hypertension, and use of ACE inhibitors.

RESULTS

Hypertension, diabetes mellitus, family history of spontaneous intracerebral hemorrhage (SICH), and low cholesterol level increase risk of female SDICH, whereas hypertension, alcohol use, smoking history, family history of SICH, and low cholesterol level are an important risk factor for male SDICH. After adjusting for covariates, only haplotype ACE T-D (OR = 2.7, 95% CI, 1.1-6.5, P = 0.02) was associated with female SDICH.

CONCLUSIONS

This study demonstrates that environmental risk factors play a major role and ACE polymorphisms play a minor role in contributing risk of SDICH in Taiwan.

Angiotensinogen gene T235 variant: a marker for the development of persistent microalbuminuria in children and adolescents with type 1 diabetes mellitus

AIM

We examined genetic polymorphisms in the renin-angiotensin system (RAS) coding for angiotensin I-converting enzyme (ACE) insertion/deletion (I/D) for angiotensinogen (AGT) M235T and angiotensin II receptor type 1 (AGTR1) A1166C as predictors for the development of microalbuminuria (MA) in children with type 1 diabetes mellitus (T1DM).

METHODS

Four hundred fifty-three (215 males, 238 females) T1DM children [median (interquartile range): age, 16.7 years (13.9-18.3); diabetes duration, 6.9 years (3.3-10.8); age at diagnosis, 9.1 years (5.8-11.8)] were followed prospectively from diagnosis until the development of MA (two of three consecutive overnight urine samples with albumin excretion rates of > or =20 and <200 microg/min). Kaplan-Meier survival curves and Cox proportional multivariate model estimated the probability of developing MA and the relative risk for MA among different variables.

RESULTS

MA developed in 41 (9.1%) subjects. The frequencies of genotypes were as follows: ACE-II 112 (25%), ACE-ID 221 (49%), and ACE-DD 117 (26%) (n=450); AGT-MM 144 (32%), AGT-MT 231 (51%), and AGT-TT 77 (17%) (n=452); AGTR1-AA 211 (47%), AGTR1-AC 204 (45%), and AGTR1-CC 37 (8%) (n=452). The cumulative risk for the development of MA was higher in ACE-DD versus ACE-ID/II groups (log-rank test, P=.05), and a trend was noticed when AGT-TT was compared to AGT-MT/MM groups (log-rank test, P=.08). AGT-TT polymorphism conferred a fourfold increased risk for MA compared to AGT-MM/MT (hazard ratio=3.8; 95% confidence interval=1.43-10.3; P=.008).

INTERPRETATION

Our findings suggest that RAS gene polymorphism at AGT M235T is a strong predictor for early MA in young T1DM subjects.

ACE I/D polymorphism study in a Cuban hypertensive population

BACKGROUND

The angiotensin converting enzyme (ACE) is a key protein of the renin angiotensin system, whose main function is the conversion of angiotensin I to II. ACE is involved in the physiological control of blood pressure and it is a candidate gene for essential hypertension in humans. We tested the relevance of the ACE insertion/deletion (I/D) polymorphism in our population.

METHODS

We recruited 243 hypertensive and 407 normotensive subjects in the city of Havana, matched according to age, sex and ethnic group. The ACE (I/D) polymorphism was determined by the polymerase chain reaction (PCR) technique. The fit of genotype frequencies to Hardy-Weinberg proportions was evaluated in all groups analyzed. The possible association between the ACE I/D polymorphism and hypertension status was tested by chi2 and odds ratio tests.

RESULTS

All groups but black female cases were in Hardy-Weinberg equilibrium. The frequencies of the D allele in hypertensive/normotensive subjects were 0.61/0.59 in white males, 0.58/0.58 in white females, 0.47/0.59 in black males and 0.58/0.54 in black females. The distribution of ACE genotypes differed significantly between cases and controls only in black women according to the additive model (chi2p=0.04) but the adjusted OR did not show significant association (OR 1.14 95% CI 0.62 to 2.10).

CONCLUSION

The ACE I/D polymorphism was not associated with hypertension in our multiethnic sample. While the chi2 test for additive model in black women suggested a marginal significance, the adjusted OR did not show any significant association.

The search for the genetic basis of hypertension

PURPOSE OF REVIEW

This review surveys the literature on the search for the genetic basis of hypertension during the 10 months since November 2003. The goals set forth by this search are defined and the highlights of the work accomplished are provided.

RECENT FINDINGS

The search for the genetic basis of hypertension is ongoing, generating an abundance of new data. These data consist of a large number of candidate genes, association of previously known and novel candidate genes with various facets of hypertension, detection of new quantitative trait loci and identification of genes that mediate susceptibility to hypertension. The renin-zangiotensin-aldosterone system continues to dominate the interest of investigators. Other gene systems are also emerging but a single-gene system cannot be singled out beyond the renin-angiotensin-aldosterone system and the data are mostly sporadic and do not reflect a guided or coordinated effort to resolve unanswered issues. The notion that hypertension is polygenic is reinforced, yet few data are provided as to the actual number of genes involved, gene-gene interaction or gene-environment interaction. Advanced biotechnological tools involving transcriptomics and proteomics are underused.

SUMMARY

Research on the genetic basis of hypertension has generated over the past year a large number of candidate genes and tied them to various aspects of hypertension. How these genes fit into the complex pathophysiological network that induces hypertension remains unclear. The task of putting together these genes into a cohesive framework still lies ahead, but promises to enlighten us as to the true nature of hypertension, the pathogenic mechanisms involved and improved therapeutic and preventive measures.

Effects of canrenoate plus angiotensin-converting enzyme inhibitors versus angiotensin-converting enzyme inhibitors alone on systolic and diastolic function in patients with acute anterior myocardial infarction

BACKGROUND

Aldosterone (ALDO) exerts profibrotic effects, acting via the mineralocorticoid receptors in cardiovascular tissues. Aldosterone antagonism in combination with angiotensin-converting enzyme inhibition may better protect against the untoward effects of ALDO than angiotensin-converting enzyme inhibition alone.

METHODS

In a double-blind randomized study, the tolerability and efficacy of canrenoate (25 mg/d) plus captopril versus captopril alone were evaluated in 510 patients with an acute anterior myocardial infarction (MI), a serum creatinine concentration < 2.0 mg/dL, and a serum potassium level < 5.0 mmol/L. Three hundred forty-one patients received captopril and 25-mg canrenoate (group A). Group B (346 patients) received captopril and placebo. At baseline and at 10, 90, and 180 days after admission, Doppler echocardiography was performed.

RESULTS

Clinical and demographic aspects were similar in both groups. In addition, baseline cardiac enzyme levels, left ventricular function, and incidence of surgical interventions and angioplasty were comparable. Overall, creatinine, blood urea, and serum potassium levels did not show significant differences between groups. However, in 18 patients in group A, increases in serum potassium levels to > 5.5 mEq/L and creatinine levels to > 2.0 mg/L after 10 days of treatment were observed. At 180 days, the mitral E-wave-A-wave ratio was higher (P = .0001) and left ventricular end-systolic volume was smaller (P = .0001) in patients treated with canrenoate than in those receiving placebo. No further side effects were observed during the study period.

CONCLUSIONS

Our data suggest that the combination of captopril plus canrenoate is well tolerated after an acute MI and has beneficial effect on systolic and diastolic parameters and may decrease post-MI remodeling.

Lack of an association between the angiotensin-converting enzyme insertion/deletion polymorphism and intracranial aneurysms in a Caucasian population in the United States

OBJECT

The identification of polymorphisms associated with an increase in the risk of developing disease is integral to the development of genetic biomarkers to identify individuals at risk. Based on reports indicating a role for angiotensin-converting enzyme (ACE) in the pathogenesis of intracranial aneurysms (IAs) as well as hypertension, an independent risk factor for IAs, the authors investigated the association between an insertion/deletion (I/D) polymorphism in the ACE gene and IAs in a Caucasian population in the US.

METHODS

The patient population consisted of 162 randomly selected Caucasian patients who underwent surgical repair of an IA at Memorial-Hermann Hospital (Houston, TX) and had no family history of the disease. The ACE I/D polymorphism was typed using polymerase chain reaction amplification of genomic DNA, and allele and genotype frequencies were compared between the patients with IAs and 143 healthy Caucasian volunteers (control group) by performing logistic regression and chi-square tests. The ACE I/D allele frequencies did not differ significantly between the patient and control populations. There were similar allele and genotype frequencies in male and female study participants in both patient and control populations. The authors found no evidence of an association between the allelic or genotypic distribution of the ACE I/D polymorphism and aneurysmal subarachnoid hemorrhage or unruptured IAs.

CONCLUSIONS

Contrary to findings in two European Caucasian populations (one British and one Polish), this polymorphism did not contribute to the risk of developing IAs in a Caucasian population in the US.

Angiotensin-converting enzyme, sleep-disordered breathing, and hypertension

The angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism influences ACE activity, cardiovascular risk, blood pressure, and possibly the risk of developing Alzheimer's dementia. We explored the association of the insertion/deletion polymorphism with sleep-disordered breathing (SDB) and hypertension in 1,100 subjects of the Wisconsin Sleep Cohort. The polymorphism did not influence body mass index or the occurrence of SDB, but was dose-dependently associated with blood pressure. Interestingly, SDB and the insertion/deletion polymorphism interacted significantly to modulate blood pressure independently of age, sex, ethnicity, and body mass index. Most specifically, the association of the deletion allele with hypertension was most pronounced in subjects with mild to moderate degrees of sleep apnea (5 < or = apnea-hypopnea index < or = 30). We hypothesize that in the absence of SDB the effect of the deletion allele alone may not be sufficient to increase blood pressure. At severe levels of SDB, the effect of sleep apnea on blood pressure overwhelms any association of the deletion allele with hypertension and occurs independent of any ACE gene genotype.