Angiotensin-converting enzyme and angiotensin II receptor 1 polymorphisms: association with early coronary disease

Association of Endothelial Nitric Oxide Synthase and Angiotensin-Converting Enzyme Genes Polymorphism With In-Sent Restenosis of Bare Metal Stents vs Drug-Eluting Stents in Egyptians

Despite its unequivocal superiority compared with balloon angioplasty, coronary stenting did not abolish restenosis. We aimed to evaluate the associations between a common single nucleotide polymorphism occurring in endothelial nitric oxide synthase (eNOS) and angiotensin-converting enzyme (ACE) genes and the risk of in-stent restenosis (ISR) of bare metal stents vs drug-eluting stents (BMS vs DES) implanted in Egyptian patients. Two hundred patients who had coronary stenting were divided into group I (n = 98) who received a BMS and group II (n = 102) who received a DES. eNOS and ACE genes polymorphism were analyzed by polymerase chain reaction (PCR). We found that the GA and AA genotypes of the eNOS gene were associated with the ISR with both BMS and DES. However, the ACE gene was not associated with ISR. We concluded that eNOS gene polymorphism is associated with ISR. Hypertension, stent length, and AA genotype of the eNOS gene were found to be independent predictors of the occurrence of ISR after both BMS and DES use.

The Genetic Variants in the Renin-Angiotensin System and the Risk of Heart Failure in Polish Patients

(1) Background: Heart failure (HF) is a complex disease and one of the major causes of morbidity and mortality in the world. The renin-angiotensin system (RAS) may contribute to the pathogenesis of HF. (2) Aim: To investigate the association of RAS key genetic variants, rs5051 (A-6G) in the gene encoding angiotensinogen (AGT), rs4646994 (I/D) in the gene for angiotensin I converting enzyme (ACE), and rs5186 (A1166C) in the gene encoding type 1 receptor for angiotensin II (AGTR1), with the HF risk in the cohort of Polish patients. (3) Methods: The study group consisted of 415 patients that were diagnosed with HF, while the control group comprised of 152 healthy individuals. Genomic DNA were extracted from blood and genotyping was carried out using either PCR or PCR-RFLP for ACE or AGT and AGTR1 variants, respectively. (4) Results: No association has been found between the I/D ACE and heart failure. The HF risk was significantly higher for AG AGT heterozygotes (overdominance: AG versus AA + GG) and for carriers of the G AGT allele in codominant and dominant modes of inheritance. However, the risk of HF was significantly lower in the carriers of at least one C AGTR1 allele (AC or CC genotypes) or in AC AGTR1 heterozygotes (overdominant mode). There was a significant relationship for AGT and HF patients in NYHA Class I-II for whom the risk was higher for the carriers of the G allele, and for the AG heterozygotes. There was also a significant interaction between heterozygote advantage of AGT and BMI increasing the risk for HF. (5) Conclusion: Our results suggest that the A(-6)G AGT polymorphism may be associated with HF in the Polish population and the HF risk seems to be modulated by the A1166C AGTR1 polymorphism.

Angiotensin-converting enzymes (ACE, ACE2) gene variants and COVID-19 outcome

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The Angiotensin system has been implicated in the pathogenesis of COVID-19.

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Functional ACE/ACE2 polymorphisms might contribute to the outcome of COVID-19.

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Severe COVID-19 was associated with hypertension, male gender, and ACE-DD genotype.

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The ACE2 polymorphism was not associated with the disease outcome.

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ACE2 showed no coding variants that could explain an increased risk of COVID-19.

The Angiotensin system is implicated in the pathogenesis of COVID-19. First, ACE2 is the cellular receptor for SARS-CoV-2, and expression of the ACE2 gene could regulate the individuaĺs susceptibility to infection. In addition, the balance between ACE1 and ACE2 activity has been implicated in the pathogenesis of respiratory diseases and could play a role in the severity of COVID-19. Functional ACE1/ACE2 gene polymorphisms have been associated with the risk of cardiovascular and pulmonary diseases, and could thus also contribute to the outcome of COVID-19.

We studied 204 COVID-19 patients (137 non-severe and 67 severe-ICU cases) and 536 age-matched controls. The ACE1 insertion/deletion and ACE2 rs2285666 polymorphism were determined. Variables frequencies were compared between the groups by logistic regression. We also sequenced the ACE2 coding nucleotides in a group of patients.

Severe COVID-19 was associated with hypertension male gender (p < 0.001), hypertension (p = 0.006), hypercholesterolaemia (p = 0.046), and the ACE1-DD genotype (p = 0.049). In the multiple logistic regression hypertension (p = 0.02, OR = 2.26, 95%CI = 1.12–4.63) and male gender (p = 0.002; OR = 3.15, 95%CI = 1.56–6.66) remained as independent significant predictors of severity. The ACE2 polymorphism was not associated with the disease outcome. The ACE2 sequencing showed no coding sequence variants that could explain an increased risk of developing COVID-19.

In conclusion, an adverse outcome of COVID-19 was associated with male gender, hypertension, hypercholesterolemia and the ACE1 genotype. Our work suggested that the ACE1-I/D might influence COVID-19 severity, but the effect was dependent on the hypertensive status. This result requires further validation in other large cohorts.

Gene variants in the NF-KB pathway (NFKB1, NFKBIA, NFKBIZ) and risk for early-onset coronary artery disease

The nuclear-factor kappa-beta (NF-KB) is a driver of inflammation, and plays an important role in the pathogenesis of atherosclerosis and coronary artery disease (CAD). Early-onset CAD is defined as a coronary ischaemic episode at an age ≤55 years, and in our population was strongly associated with male sex and smoking. Our aim was to determine whether common variants in three NF-KB genes were associated with early-onset CAD. We studied 609 patients with early-onset CAD and 423 healthy controls, all male. Allele and genotype frequencies for the NFKB1 rs28362491 (-94 delATTG) and NFKBIA rs8904 were not significantly different between the two groups. For the NFKBIZ rs3217713, the deletion allele was significantly more frequent in the patients than in controls (0.27 vs. 0.22; p = 0.004). Deletion-carriers were more frequent in the patients (p < 0.001), with an OR = 1.48 (95%CI = 1.15-1.90). We performed a multiple logistic regression (linear generalized model) with smoking, hypercholesterolemia, type 2 diabetes, hypertension, and the rs3217713 deletion carriers remained significantly associated with early-onset CAD (p = 0.01). In our population, the NFKBIZ variant was an independent risk factor for developing early-onset CAD.

The Angiotensin Converting Enzyme I/D Polymorphism in Turkish Athletes and Sedentary Controls

The angiotensin converting enzyme (ACE) gene is located on human chromosome 17 expressing three genotypes within the intron 16 of the related gene structure. These genotypes are classified as I and D alleles which are termed as insertion and deletion, respectively. This study was carried out to identify possible relationships between the insertion/ deletion (I/D) polymorphisms and athletic performance in Turkish athletes. To be able to determine these relationships, eighty healthy athletes and eighty healthy sedentary controls were genotyped for the ACE I/D polymorphism at gene level. According to the results obtained, we found significant difference on ACE I/D polymorphism in between athletes and healthy controls (x2 = 7.32, df = 2, P = 0.026). This result supports the association in ACE genotype in Turkish athletes, suggesting that this might be a genetic factor influencing the physical performance.

Association of renin-angiotensin system genes polymorphisms and risk of premature ST elevation myocardial infarction in young Mexican population

: The renin-angiotensin system plays an important role in the regulation of blood pressure and the development of coronary artery disease. The aim was to examine the association of the insertion deletion in the angiotensin-converting enzyme gene, M235T and T174M polymorphisms in the angiotensinogen gene with ST elevation acute myocardial infarction (STEAMI) in young Mexican population. We analyzed 242 unrelated patients with STEAMI 45 or less years of age, admitted to a cardiovascular intense care unit, and 242 individuals without STEAMI matched by age and sex, recruited from January 2006 and June 2013. The polymorphisms insertion deletion, M235T and T174M were determined in all participants by a polymerase chain-reaction-restriction fragment length polymorphism assay. There was a significant difference in the insertion deletion genotype distribution between two groups (P = 0.03) and a higher percentage of the T allele M235T polymorphism in the group of STEAMI patients (P = 0.02). The T174M polymorphism was not associated (P = 0.08). The insertion deletion and M235T polymorphisms, smoking, hypertension, familial history of cardiovascular disease and dyslipidemia were independent risk factors for STEAMI. Our results identified that the D allele from the insertion deletion and M235T but not T174M polymorphisms represent an independent risk factor for STEAMI in young Mexican population.

Association between angiotensin II type-1 receptor A1166C polymorphism and the presence of angiographically-defined coronary artery disease in an Iranian population

Background: There are reported associations between a polymorphism of the angiotensin II type 1 receptor (AT1R/A1166C) gene and coronary artery disease (CAD), hypertension, and myocardial infarction in some populations. Objective: Investigate the association between A1166C polymorphism and CAD in an Iranian population. Methods: Four hundred and thirteen patients with suspected CAD were recruited. Based on coronary angiography, the patients were classified into CAD+ (n=315) and CAD- (n=98) groups defined as >50% and <50% stenosis of any major coronary artery, respectively. One hundred and thirty-five healthy subjects were also recruited as the control group. The AT1R polymorphism was assessed using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based method. Results: A higher frequency of the AC and CC genotypes and lower frequency of the AA genotype was observed in both CAD+ and CAD- groups, compared with the control group (p <0.05). CAD+ and CAD- groups also had a higher frequency of the C allele than controls (p <0.01). There was no significant difference in genotype and allele frequencies between hypertensive and non-hypertensive patients (p > 0.05). In addition, the AT1R genotype frequencies did not differ significantly among different subgroups of CAD+ patients, based on the number of affected coronary vessels (p >0.05). Conclusion: The frequency AT1R/A1166C polymorphism was higher among patients with some degrees of coronary stenosis who are candidates of coronary angiography.

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.

Renin-angiotensin system gene polymorphisms and premature coronary heart disease

Introduction

Experimental and clinical studies demonstrated that the renin-angiotensin system (RAS) affects the pathogenesis of atherosclerosis and prognosis of coronary heart disease (CHD). The aim of this study was to investigate the genotype distribution and the allele frequencies of three RAS genes polymorphisms and their effects on premature CHD in a Turkish population.

Materials and methods

One-hundred and fifteen Turkish patients with premature CHD and 128 controls were included into the study. Angiotensin-converting enzyme (ACE), angiotensin II type 1 (AT1) receptor and angiotensinogen (AGT) gene polymorphisms were analysed by polymerase chain reaction (PCR ) and restriction fragment length polymorphism (RFLP).

Results

The patients group showed an increased frequency of the ACE D allele compared with controls (65% vs. 35%, p=0.0001). There was a significant association between the DD genotype and premature CHD (ACE DD vs. ID and II; odds ratio [OR]=2.82 [CI 95% 1.33—2.91, p=0.002]). Also, we observed increased premature CHD risk associated with higher frequencies of the AGT MM genotype in patients when compared with controls (AGT MM vs. TT and MT, OR=1.92 [CI 95% 1.11—3.33, p=0.018]). We found a significant association between AT1-receptor AA genotype and decreased risk of premature CHD (AT1R AA vs. AC and CC, OR= 0.57[CI 95% 0.34—0.95, p=0.03]).

Conclusions

We demonstrated that increased premature CHD risk is associated with higher frequencies of the ACE DD and AGT MM genotypes. These findings indicate a synergistic contribution of ACE DD and AGT MM polymorphisms to the development of premature CHD. Also, our results suggest that family history, smoking, diabetes, hypertension, obesity and ACE DD genotype were independent risk factors for premature CHD.

Renin-Angiotensin System Polymorphisms and Coronary Artery Surgery Patients

The frequencies of angiotensin-converting enzyme gene insertion/deletion, angiotensinogen-M253T, and angiotensin II type 1 receptor-A1166C polymorphisms were analyzed in 105 patients undergoing coronary artery bypass grafting (group 1) and a control group of 105 non-cardiac patients (group 2). Blood samples were obtained for biochemical analyses and DNA extraction. Genotyping was performed by polymerase-chain-reaction-based restriction analysis. According to the angiotensin-converting enzyme gene insertion/deletion polymorphism, 36.3% of patients in group 1 and 30.7% in group 2 were homozygous for the DD allele. This difference was not statistically significant. Angiotensin II type 1 receptor-A1166C genotype polymorphism was also not significantly different between the groups. The results showed the angiotensinogen-M235T polymorphism to be heterogenous. The MM homozygote frequency was significantly higher in controls (72.3%), whereas 80% of the TT homozygote frequency was in the surgical group ( p = 0.001). These results show that although there were no significant differences in angiotensin-converting enzyme gene insertion/deletion and angiotensin II type 1 receptor-A1166C genotype polymorphisms between the groups, angiotensinogen-M235T polymorphism of TT homozygote frequency was significantly associated with patients undergoing coronary artery bypass surgery.

Influence of ACE I/D Polymorphism on Circulating Levels of Plasminogen Activator Inhibitor 1, D-Dimer, Ultrasensitive C-Reactive Protein and Transforming Growth Factor β1 in Patients Undergoing Hemodialysis

BACKGROUND

There is substantial evidence that chronic renal and cardiovascular diseases are associated with coagulation disorders, endothelial dysfunction, inflammation and fibrosis. Angiotensin-Converting Enzyme Insertion/Deletion polymorphism (ACE I/D polymorphism) has also be linked to cardiovascular diseases. Therefore, this study aimed to compare plasma levels of ultrassensible C-reactive protein (usCRP), PAI-1, D-dimer and TGF-β1 in patients undergoing HD with different ACE I/D polymorphisms.

METHODS

The study was performed in 138 patients at ESRD under hemodialysis therapy for more than six months. The patients were divided into three groups according to the genotype. Genomic DNA was extracted from blood cells (leukocytes). ACE I/D polymorphism was investigated by single polymerase chain reaction (PCR). Plasma levels of D-dimer, PAI-1 and TGF-β1 were measured by enzyme-linked immunosorbent assay (ELISA), and the determination of plasma levels of usCRP was performed by immunonephelometry. Data were analyzed by the software SigmaStat 2.03.

RESULTS

Clinical characteristics were similar in patients with these three ACE I/D polymorphisms, except for interdialytic weight gain. I allele could be associated with higher interdialytic weight gain (P = 0.017). Patients genotyped as DD and as ID had significantly higher levels of PAI-1 than those with II genotype. Other laboratory parameters did not significantly differ among the three subgroups (P = 0.033). Despite not reaching statistical significance, plasma levels of usCRP were higher in patients carrying the D allele.

CONCLUSION

ACE I/D polymorphisms could be associated with changes in the regulation of sodium, fibrinolytic system, and possibly, inflammation. Our data showed that high levels of PAI-1 are detected when D allele is present, whereas greater interdialytic gain is associated with the presence of I allele. However, further studies with different experimental designs are necessary to elucidate the mechanisms involved in these associations.

Role of angiotensin II type I (AT1 A1166C) receptor polymorphism in susceptibility of left ventricular dysfunction

BACKGROUND

Left ventricular dysfunction (LVD) with subsequent congestive heart failure (CHF) constitutes the final common pathway for a host of cardiac disorders. The impaired LV function develops in response to an ischemic insult followed by a fall in cardiac output that leads to activation of renin-angiotensin-system (RAS). Angiotensin II type I receptor (AT1), which mediate the vasoconstrictive and salt-conserving actions of the RAS, represent interesting candidate genes for cardiovascular diseases. Therefore, we conducted an association study between single nucleotide polymorphism (SNP) in AT1 gene and LVD in CAD patients.

METHODS AND RESULTS

The present study recruited a total of 950 subjects including 720 angiography confirmed CAD patients and 230 healthy controls. Among 720 CAD patients, 229 with reduced left ventricle ejection fraction (LVEF≤45%) were categorized as LVD. The AT1 (A1166C, rs5186) polymorphism was determined by ARMS-PCR. Our results showed that the frequency of AT1 1166AC and CC genotypes were significantly higher in LVD patients in comparison to non-LVD (LVEF >45%) patients (p value = 0.003; OR = 1.81 and p value <0.001; OR = 4.33). Further analysis showed that AT1 A1166C polymorphism was significantly associated with LV end diastole (p-value = 0.031), end systole (p-value = 0.038) dimensions, and mean LVEF (p-value = 0.035). Moreover, on comparing the AT1 A1166C polymorphism in CAD patients with healthy controls, we did not find any association both at genotypic and allelic level (p value = 0.927; OR = 1.04 and p value = 0.219; OR = 0.83) respectively.

CONCLUSIONS

Our study suggests that AT1 A1166C polymorphism may play significant role in conferring genetic susceptibility of LVD.

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.

Association of angiotensin II type I and type II receptor genes polymorphisms with the presence of premature coronary disease and metabolic syndrome

Premature coronary artery disease (PCAD) is known to have a particularly strong genetic component. We aimed to investigate the association between angiotensin II receptor type 1 (ATR1) or type II (ATR2) genes polymorphisms and PCAD with or without metabolic syndrome in males. 132 male patients with PCAD and 132 controls were included in the study. ATR1 and ATR2 genes polymorphisms were analyzed by polymerase chain reaction. The present study revealed that ATR1 CC genotype and ATR2 G allele increased the risk of PCAD by 2.9 and 1.3 respectively as well as they increased susceptibility to metabolic syndrome by 4.5 and 2.3 respectively. The present study proved that diabetes, smoking, obesity, total cholesterol, triglycerides, LDLc and HDLc were independent risk factors for the development of PCAD. We concluded that ATR1 CC genotype and ATR2 G allele increased the susceptibility of Egyptian males to have PCAD. The increased susceptibility to have metabolic syndrome could be one of the mechanisms leading to the development of PCAD in subjects carrying one or both of these polymorphisms.

Association between angiotensin II type 1 receptor polymorphism and sudden cardiac death in myocardial infarction

Objective. The renin-angiotensin system is involved in the pathogenesis of coronary artery disease and myocardial infarction (MI). Angiotensin II (Ang II) has many adverse effects such as vasoconstriction and vascular remodeling, and these actions are mediated by the angiotensin II type 1 receptor (AT1R). Patients and Methods. A total of 1376 patients were recruited from January 2010 to April 2012. The study group consisted of 749 patients with ACS (317 females and 432 males) and of 627 healthy controls. Results. The ACS patients demonstrated a lower proportion of AA genotypes and AC genotypes but higher proportions of CC genotypes than the control population. The AT1R CC genotype conferred a 2.76-fold higher risk of MI compared with the genotype AC and AA. In addition, the CC genotype was also associated with a 4.08 times higher risk of left anterior descending artery infarction and a 3.07 times higher risk of anterior wall infarction. We also found that the CC genotype was independently associated with sudden cardiac death. In Summary. This study demonstrated that the AT1R CC genotype is an independent risk factor for ACS incidence, and this genotype is associated with a greater ACS severity and greater risk of sudden cardiac death.

Angiotensin II type 1 receptor A1166C gene polymorphism and essential hypertension in Calabar and Uyo cities, Nigeria

OBJECTIVES:

The angiotensin II protein is a vasoconstrictor that exerts most of its influence through the angiotensin II type 1 receptor (AT₁R). Inconsistent association between the A1166C polymorphism of the AT₁R gene and hypertension has been reported among various populations but not among the peoples of Calabar and Uyo. This study was designed to determine the frequency of the A1166C polymorphism of the AT₁R gene and its association with hypertension in a sample population of Calabar and Uyo.

MATERIALS AND METHODS:

A population-based case control design consisting of total of 1224 participants, 612 each of patients and controls were randomly recruited from hypertension clinics and the general population. Genotyping of the A1166C allele of the AT₁R gene to identify variants was performed using polymerase chain reaction and restriction enzyme digestion. Multiple regressions were applied to test whether the A1166 genotypes were predictors of hypertension.

RESULTS:

99% of the study population had the wild type AA genotype, and 1% was AC heterozygous carriers of the A1166C polymorphism.

CONCLUSION:

The A1166C polymorphism was not a predictor of hypertension in the sample population of Calabar and Uyo.

Lack of association of angiotensin II type 1 receptor A1166C gene polymorphism with the risk of end-stage renal disease

The association between angiotensin II type 1 receptor (AT1R) A 1166C (rs5186) gene polymorphism and end-stage renal disease (ESRD) risk remains controversial. We aimed to assess the association between AT1R A1166C gene polymorphism and ESRD susceptibility by performing a meta-analysis. Eligible studies were searched according to a predefined criterion using electronic databases. Eight articles were identified for the analysis of the association between AT1R A1166C gene polymorphism and ESRD risk. A allele and AA genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.834 and 0.832, Caucasians: p = 0.853 and 0.884, Asians: p = 0.243 and 0.982). CC and AC genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.304 and 0.712, Caucasians: p = 0.510 and 0.987, Asians: p = 0.319 and 0.225). In conclusion, AT1R A1166C gene polymorphism may not be correlated with ESRD risk in overall populations, Caucasians and Asians. However, more studies should be performed in the future.

Lack of association of genetic polymorphisms of angiotensin converting enzyme 1 and angiotensin II type 1 receptor with breast cancer risk in Iranian population

We aimed to investigate the association of insertion/deletion (I/D) and A1166C polymorphisms of angiotensin I converting enzyme 1 and angiotensin II type 1 receptor genes, respectively and their combination on breast cancer risk in an Iranian population. A case-control study (70 cases, 70 controls) was performed on an Iranian population. The I/D and A1166C polymorphisms were analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism PCR, respectively. The results revealed no significant difference between cases and controls in I/D (p = 0.14) and A1166C (p = 0.94) polymorphisms after adjustment for breast cancer known risk factors. In combined genotype analysis, considering DD and AA genotypes as low-risk genotypes, women with one and two high-risk genotypes (one high-risk genotype: adjusted odds ratio (OR), 1.24; two high-risk genotypes: adjusted OR, 1.97) were at higher risk for breast cancer. Also, the highest risk for breast cancer was seen in a subgroup of postmenopausal women carriers of two high-risk genotypes (adjusted OR, 2.41). In conclusion, I/D and A1166C polymorphisms are not significantly associated with breast cancer risk in the Iranian population; however, the combination of these two polymorphisms seems to have a synergic effect on the risk of breast cancer particularly in postmenopausal women, which may deserve consideration in large-scale case-control studies.

Gender specificity of a genetic variant of angiotensin-converting enzyme and risk of coronary artery disease

Etiological factors for coronary artery disease (CAD) involve a wide range of gene and environmental interactions. One of the systems being implicated in the pathophysiology of CAD is the renin-angiotensin system (RAS). However, the genetic polymorphisms of this system have not been widely studied in Iranian patients diagnosed with CAD. The aim of this study was to assess the relationship between six gene polymorphisms of RAS components and CAD in a sample of Iranian population. A total of 374 participants were enrolled in a case/control study. The presence of CAD was determined by coronary angiography. Genotyping of six RAS gene polymorphisms was performed using a modified PCR-RFLP method. Our results revealed, for the first time, a significant independent association of angiotensin-converting enzyme (ACE) A-240T polymorphism and incidence of CAD among Iranian women (P=0.005, OR=20.4, 95% CI=2.49-41.2). There has also been a significant difference in genotype distribution of ACE A-240T (P=0.008) and angiotensin II receptor type 2 C3123A polymorphism (P=0.032) in Iranian female participants. In conclusion, TT genotype of ACE A-240T seems to be a genetic risk factor for CAD in Iranian women.

Exaggerated blood pressure response during the exercise treadmill test as a risk factor for hypertension

Exaggerated blood pressure response (EBPR) during the exercise treadmill test (ETT) has been considered to be a risk factor for hypertension. The relationship of polymorphisms of the renin-angiotensin system gene with hypertension has not been established. Our objective was to evaluate whether EBPR during exercise is a clinical marker for hypertension. The study concerned a historical cohort of normotensive individuals. The exposed individuals were those who presented EBPR. At the end of the observation period (41.7 months = 3.5 years), the development of hypertension was analyzed within the two groups. Genetic polymorphisms and blood pressure behavior were assessed as independent variables, together with the classical risk factors for hypertension. The I/D gene polymorphism of the angiotensin-converting enzyme and M235T of angiotensinogen were ruled out as risk factors for hypertension. EBPR during ETT is not an independent influence on the chances of developing hypertension. No differences were observed between the hypertensive and normotensive individuals regarding gender (P = 0.655), skin color (P = 0.636), family history of hypertension (P = 0.225), diabetes mellitus (P = 0.285), or hypertriglyceridemia (P = 0.734). The risk of developing hypertension increased with increasing body mass index (BMI) and advancing age. The risk factors, which independently influenced the development of hypertension, were age and BMI. EBPR did not constitute an independent risk factor for hypertension and is probably a preclinical phase in the spectrum of normotension and hypertension.

Genes of renin angiotensin system and coronary heart disease

Coronary constriction, proliferation of smooth muscle cells and arrhythmia are involved in the pathophysiology of coronary heart disease and its complications such as myocardial infarction and sudden death. All these effects are favoured by high angiotensin II levels. Angiotensin II is the main effector molecule of the renin angiotensin system and it acts through angiotensin II type receptors. Genetically determined differences in the expression of the components of this system could adversely affect angiotensin II concentration and subsequently heart. Consequently each component of this system represents a potential candidate in the etiology of cardiovascular disease. In this article we review the variation of the angiotensin I converting enzyme, angiotensin II type I receptor and angiotensinogen genes and their association with cardiovascular disease.

Association of angiotensin-converting enzyme polymorphism with coronary artery disease in Iranian patients with unipolar depression

OBJECTIVES

Major depressive disorder (MDD) is an increasingly recognized risk factor of coronary artery disease (CAD). The aim of this study was to assess the relationship between renin-angiotensin system (RAS) genetic polymorphisms and CAD in a sample of depressed Iranian patients.

DESIGN AND METHODS

A total of 191 patients with a history of unipolar depression were enrolled in a case/control study. The presence of MDD was reconfirmed at study entry using DSM-IV criteria and CAD was diagnosed by coronary angiography. Genotyping of six RAS genes polymorphisms was performed by a modified PCR-RFLP method.

RESULTS

DD genotype of ACE I/D was independently associated with the incidence of CAD in depressed patients (P=0.011, OR=9.41, 95% CI: 1.68-17.81). Moreover, serum creatinine (P=0.033, OR=11.91, 95%CI: 7.23-15.62) was an independent predictor of CAD among depressed individuals.

CONCLUSION

ACE I/D polymorphism may play a major role in the development of CAD amongst Iranian depressed patients.

ACE I/D, ACTN3 R577X, PPARD T294C and PPARGC1A Gly482Ser polymorphisms and physical fitness in Taiwanese late adolescent girls

Physical performance of youth is influenced by various factors, including body composition, biological maturity status, level of habitual physical activity, and muscular strength. Muscular strength has been largely attributed to genetic effects. To exclude possible confounding effects from various acquired factors, this study examined the relationships between polymorphisms of the angiotensin-converting enzyme (ACE), α-actinin-3 (ACTN3), peroxisome proliferator-activated receptor delta (PPARD), and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PPARGC1A) genes and performance as measured by six fitness tests (handgrip strength of dominant hand, 30- and 60-s sit-ups, standing long jump, 60-m dash, and 800-m run) in 170 sedentary adolescent girls with the adjustment of anthropometric characteristics. We found that subjects with the ACE DD genotype were significantly heavier than those with I allele, while those with the ACTN3 RR genotype had higher fat-free mass percentage (FFM%) than those with the XX genotype. In addition, those with the PPARD TT genotype were significantly taller, heavier, and had a greater FFM than those with the CC genotype. Subjects with the ACE DD, ACTN3 RR and PPARD TC genotype had better performance in handgrip strength, 30- and 60-s sit-up tests, and standing long jump, respectively, when individual gene was analyzed independently after adjusting anthropometric characteristics. In the gene combination analysis, subjects with ACE DD, ACTN3 RR and PPARD TT genotype had significantly greater performance in handgrip strength. Overall, the results indicate that the genes studied have a modest influence on individual performance as assessed by specific fitness and strength tests in female late adolescents.

Renin-angiotensin system genes polymorphism in Egyptians with premature coronary artery disease

Genetics polymorphism of the renin-angiotensin system (RAS) affects the pathogenesis of atherosclerosis and associated with coronary artery disease (CAD). We aimed to investigate the association between the RAS genes and premature CAD (PCAD) in Egyptians. 116 patients with PCAD, 114 patients with late onset CAD and 119 controls were included in the study. Angiotensin converting enzyme (ACE), angiotensin II receptor type 1 (ATR1) and angiotensinogen (AGT) genes polymorphisms were analyzed by polymerase chain reaction (PCR). We found that ACE DD, AGT TT and ATR1 CC increased the risk of PCAD by 2.7, 2.8 and 2.86 respectively). Smoking, hypertension, diabetes, total cholesterol, triglycerides and LDL cholesterol were independent risk factors for the development of PCAD. We conclude that the ACE DD, AGT TT and ATR1 CC genotypes may increase the susceptibility of an individual to have PCAD. The coexistence of CAD risk factors with these risky RAS genotypes may lead to the development of PCAD in Egyptian patients.

Synergism between paraoxonase Arg 192 and the angiotensin converting enzyme D allele is associated with severity of coronary artery disease

We have previously shown that angiotensin-converting enzyme (ACE) gene D allele is an independent risk factor for early onset coronary artery disease (CAD). Little is known about the concomitant presence of the ACE gene D allele and paraoxonase (PON1) codon 192 arginine (Arg) on the severity of CAD. Regarding the high rate of CAD among Iranians the aim of present study was to examine the hypothesis of synergistic effects between ACE-D and PON1-Arg alleles on predisposition and the severity of CAD in our population. The PON1 192 and ACE insertion/deletion (I/D) genotypes were detected by PCR-RFLP and PCR, respectively in 414 individuals undergoing their first coronary angiography. Patients were placed into one of two groups: CAD and control without CAD or diabetes. We mentioned the synergistic effects of both genes and not ACE gene alone is a risk factor for CAD. We found that PON1 Arg 192 and ACE D allele act synergistically to increase the risk of CAD (OR 1.3, P = 0.044). Our results showed a significant correlation between the possession of both PON1 192 Arg and the ACE D allele and the extent of CAD in CAD patients and CAD subjects without diabetes, represented by the increased frequency of three-vessel disease with OR 2.7, P = 0.046; χ(2) = 4, P = 0.046 and OR 2.4, P = 0.051; χ(2) = 3.8, P = 0.051, respectively. We found that PON1 Arg 192 and ACE D alleles act synergistically to increase the risk of CAD in CAD patients and CAD subjects without diabetes from west of Iran, who have high frequency of three-vessel disease. Our data suggest that PON1 192 Arg and the ACE D allele in combination with each other can be important independent risk factor for severity of CAD in patients carrying both PON1 192 Arg and the ACE D allele in a west population of Iran.

Is the ACE I/D polymorphism associated with extreme longevity? A study on a Spanish cohort

The 287 bp Ins(I)/Del(D) polymorphism [rs1799752] in intron 16 of the angiotensin-converting enzyme ( ACE) gene has been associated with extreme longevity (≥ 100 years) in some Caucasian and Asian cohorts, but this finding was not corroborated in other reports. We compared the allelic/genotypic frequency of the ACE I/D polymorphism among centenarians ( N = 64, 100—108 years, 89.1% female) and nonagenarians ( N = 47, 90—97 years, 76.6% female), and a control group of healthy young adults ( n = 434, age 20—40 years, 50% female). All participants were of the same Caucasian (Spanish) descent. The ACE I/D genotype met Hardy—Weinberg expectations in all the cohorts. Allelic and genotypic frequencies did not differ by sex in any of the study groups (all p > 0.2). There were no differences in allelic or genotypic frequencies between groups, for example the frequency of the D allele was 62.3% in controls vs. 65.3% in the elderly (64.8% in centenarians). In summary, the ACE I/D polymorphism is not significantly associated with extreme longevity in the Spanish population. Further research is, however, necessary using other approaches. It also remains to be determined if the interaction of ACE genotypes with some other genetic variants exerts a potential effect on longevity.

Investigation of ACE, ACE2 and AGTR1 genes for association with nephropathy in Type 1 diabetes mellitus

BACKGROUND

Polymorphisms in ACE and AGTR1 genes have been assessed in multiple studies for association with diabetic nephropathy; however, results are conflicting. The ACE2 gene has not been studied extensively for association with diabetic nephropathy.

METHODS

We investigated variants in ACE, ACE2 and AGTR1 for association with nephropathy in a case-control group (1467 participants with Type1 diabetes, case subjects n=718; control subjects n=749) of white descent with grandparents born in the British Isles. All recruited individuals were carefully phenotyped and genotyping was performed using Sequenom, Taqman and gel electrophoresis methods. The χ(2) -test for contingency tables was used to compare genotype and allele frequencies in case and control groups.

RESULTS

No departure from Hardy-Weinberg equilibrium was observed in cases or controls. Two variants within the ACE gene (rs4293, P(allelic) =0.02, P(genotypic) =0.008; rs4309, P(allelic) =0.02, P(genotypic) =0.01) were significantly associated with nephropathy at the 5% level. No variant remained statistically significant following adjustment for multiple comparisons. No single nucleotide polymorphisms in the ACE2 or AGTR1 genes were significantly associated with nephropathy when analysed either by genotype or allele frequencies.

CONCLUSIONS

Our independent case-control study provides no evidence that common variants in ACE, ACE2 and AGTR1 play a major role in genetic susceptibility to diabetic nephropathy in a white population with Type1 diabetes.

A1166C genetic variation of the angiotensin II type I receptor gene and susceptibility to coronary heart disease: collaborative of 53 studies with 20,435 cases and 23,674 controls

OBJECTIVE

Angiotensin II induces vasoconstriction and vascular smooth muscle growth via stimulation of the angiotensin II type I receptor (AGTR1). Some studies have reported an association between a genetic variant (A1166C) in the 3' un-translated region of AGTR1 and increased risk of coronary heart disease (CHD), but other have yielded apparently conflicting results.

METHODS

Literature-based meta-analyses were performed on 48 papers including 53 studies published before June 2008 in relation to the A1166C polymorphism (NCBI, dbSNP: rs5186) of the AGTR1, involving a total of 20,435 CHD cases and 23,674 controls. We also explored potential sources of heterogeneity and conducted appropriate stratified analyses.

RESULTS

In a combined analysis, the per-allele odds ratio (OR) for CHD of the A1166C polymorphism was 1.11 (95% confidence interval: 1.03-1.19), but there is an indication of publication bias and heterogeneity among the 53 studies. Sample size and study quality were significant sources of heterogeneity among studies of the A1166C polymorphism with possibly overestimates in studies of smaller sample-size and poor-quality. When the analyses were restricted to 11 larger studies (≥500 cases), and to 8 high-quality studies (quality score: ≥11 points), the summary per-allele odds ratios were 0.992 (95% confidence interval, 0.944-1.042) and 0.990 (95% confidence interval, 0.915-1.072), respectively.

CONCLUSIONS

An overall weak association between the A1166C polymorphism and CHD is observed but this is likely to be due to publication bias and heterogeneity between studies. There were no significant associations among the larger sample-size and high-quality studies which are less prone to selective publication and have greater power to detect a true association.

The angiotensin converting enzyme D allele is an independent risk factor for early onset coronary artery disease

OBJECTIVE

The role of angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in early onset coronary artery disease age < 55years (ECAD) is controversial. The aim of this study was to further evaluate the role of this ACE(I/D) gene polymorphism on the risk of premature CAD in patients from western Iran.

METHODS

The ACE(I/D) genotypes were detected by PCR-RFLP in 323 individuals undergoing their first coronary angiography. Patients were placed into two groups: ECAD and late onset CAD age ≥ 55years (LCAD).

RESULTS

We found a statistically significant association of the ACE D allele, as homozygous or ACE ID plus DD genotypes (ID+DD), only in the ECAD subjects OR=1.35, p=0.015, OR=3.27, p=0.014, and OR=2.8, p=0.013, respectively. In addition, there was a significant association after adjustment for the absence of history of diabetes, presence of normolipidemia and absence of history of blood pressure [OR 1.38, p=0.017 and 2.35, p=0.02]. Our results indicated that the ACE D allele is a risk factor for early onset of CAD even after correcting for conventional risk factors. The incidence of triple vessel disease was significantly higher in individuals carrying ACE(D/D) genotype in ECAD patients compared to those who carried ACE(I/I) genotype (OR 3.38; p=0.019; 57.5% vs. 42.5%; p=0.013).

CONCLUSION

The presence of D allele of ACE can be important independent risk factor in the onset of CAD patients less than 55 years old in a west population of Iran. Larger collaborative studies are needed to confirm these results.

Functional polymorphisms in genes of the Angiotensin and Serotonin systems and risk of hypertrophic cardiomyopathy: AT1R as a potential modifier

Background

Angiotensin and serotonin have been identified as inducers of cardiac hypertrophy. DNA polymorphisms at the genes encoding components of the angiotensin and serotonin systems have been associated with the risk of developing cardiovascular diseases, including left ventricular hypertrophy (LVH).

Methods

We genotyped five polymorphisms of the AGT, ACE, AT1R, 5-HT2A, and 5-HTT genes in 245 patients with Hypertrophic Cardiomyopathy (HCM; 205 without an identified sarcomeric gene mutation), in 145 patients with LVH secondary to hypertension, and 300 healthy controls.

Results

We found a significantly higher frequency of AT1R 1166 C carriers (CC+AC) among the HCM patients without sarcomeric mutations compared to controls (p = 0.015; OR = 1.56; 95%CI = 1.09-2.23). The AT1R 1166 C was also more frequent among patients who had at least one affected relative, compared to sporadic cases. This allele was also associated with higher left ventricular wall thickness in both, HCM patients with and without sarcomeric mutations.

Conclusions

The 1166 C AT1R allele could be a risk factor for cardiac hypertrophy in patients without sarcomeric mutations. Other variants at the AGT, ACE, 5-HT2A and 5-HTT did not contribute to the risk of cardiac hypertrophy.

Association analysis of TNFR2, VDR, A2M, GSTT1, GSTM1, and ACE genes with rheumatoid arthritis in South Asians and Caucasians of East Midlands in the United Kingdom

Genetic associations of TNFR2, VDR (Bsm I and Fok I), A2M, GSTT(1), GSTM(1) and ACE in South Asian and Caucasian patients with rheumatoid arthritis (RA) were assessed in this study. DNA samples from South Asians (134 cases, 149 controls) and Caucasians (137 cases, 150 controls) from the East Midlands of the United Kingdom were genotyped for seven polymorphisms. All cases were rheumatoid-factor positive. Significant genetic associations were observed with TNFR2 R-R (OR = 3.16, CI 1.20-9.26, P < 0.05), A2M 1-1 (OR = 2.09, CI 1.21-3.64, P < 0.05) and GST T(1)null (OR = 1.97, CI 1.07-3.68, P < 0.05) among Caucasian patients. In South Asians, VDR Bsm I B-B genotype (OR = 2.08, CI 1.23-3.52, P < 0.05), A2M 2-2 genotype (OR = 3.99, CI 1.19-17.18, P < 0.05), and GST T(1)null genotype (OR = 2.81, CI 1.40-5.77, P < 0.002) genotypes were associated with RA. In the majority of cases, recessive and multiplicative modes of inheritance explained the observed associations. This study demonstrates that ethnicity affects the genetic associations in RA.

Renin-angiotensin-aldosterone system gene polymorphisms in coronary artery bypass graft surgery patients

INTRODUCTION

Candidates for coronary artery bypass grafting (CABG) represent a group of patients with well documented, severe coronary artery disease (CAD). Genetic polymorphisms of renin-angiotensin-aldosterone system (RAAS) components have been associated with CAD. We examined the association of polymorphisms of angiotensin-converting enzyme (ACE), angiotensinogen (AGT), and angiotensin II type 1 receptor (AT(1) receptor) with severe CAD in CABG patients.

MATERIALS AND METHODS

One hundred and fifty-four CABG patients and 155 non-CAD controls were included in the study. Established PCR methods were used for genotyping of AGT M235T, AGT T174M, AT(1) receptor A1166C, and ACE I/D polymorphisms. Cumulative effect of analysed polymorphisms was assessed by calculation of each individual's RAAS gene score (addition of 0.5 points for each variant allele and then calculating the sum for all four polymorphisms).

RESULTS

No association between AGT M235T, AGT T174M, ACE I/D and AT(1) receptor A1166C polymorphisms and CAD was observed. Within CABG patients, the frequency of homozygous AGT 235TT genotype was higher in hypertensive compared to normotensive CABG patients (21.7% vs. 6.3%, p=0.03). RAAS gene score did not differ between CABG patients and non-CAD controls.

CONCLUSIONS

There is no association of the analysed RAAS polymorphisms with severe CAD in CABG patients. However, within these patients, an association was found between AGT 235TT genotype and hypertension.

Allelic frequencies at the ACE and LRPAP1 loci suggest age-related relationships in a Northern Italian population

The present work attempts to determine the distribution of ACE and LRPAP1 genotypes and allele frequencies in a sample of the population of north-western Italy and to examine the age-related association of these polymorphisms. ACE D allele frequency found in this work further confirms data obtained in previous studies of Northern Italian populations. Regarding the LRPAP1 gene, high frequencies of the deleted allele in European populations were also confirmed. In order to analyse the relationship between ACE and LRPAP1 gene polymorphisms and age, the sample was subdivided into four age groups: 1-30 (n= 99), 31-50 (n= 165), 51-79 (n= 146) and 80-100 years old (n= 57). For the ACE gene, significant difference in D/D genotype frequency was found only between the younger and the 51-79 age groups (p<0.05), the latter showing the lower frequency value. Significant differences were found, for both the I/D and D/D LRPAP1 genotypes, between the first and the second age group (p < 0.02) and between the first and the third age group (p < 0.01), with the 51-79 age group showing the higher D/D and the lower I/D genotype frequency values.

Genetic variations of Mrf-2/ARID5B confer risk of coronary atherosclerosis in the Japanese population

A phenotypic change of smooth muscle cells (SMCs) is considered to be critical in the pathogenesis of atherosclerotic lesions such as coronary artery disease (CAD). Mrf-2/ARID5B, a member of the AT-rich interaction domain family of transcription factors, is highly expressed in the cardiovascular system and is believed to play essential roles in the phenotypic change of SMCs through its regulation of SMC differentiation. In addition, recent studies on gene-engineered mice suggested that this transcriptional factor is involved in obesity and adipogenesis, which are critical aspects for the pathogenesis of atherosclerosis. Thus, we hypothesized that genetic variations of the Mrf-2 gene might be associated with susceptibility to CAD. We investigated 11 common genetic variations of Mrf-2 to determine whether they were associated with susceptibility to CAD in 475 CAD subjects and 310 control subjects. The prevalence of homozygotes for the minor allele G of SNP4 (rs2893880) and minor allele G of SNP6 (rs7087507) were significantly more frequent in the control subjects than in patients with CAD (P=0.0002, rs2893880, P=0.0058, rs7087507). Four nearby SNPs (SNP4 to SNP7) (rs2893880, rs10740055, rs7087507 and rs10761600) showed almost complete linkage disequilibrium, and haplotype analysis revealed that the haplotype G (rs2893880)-C (rs10740055)-G (rs7087507)-A (rs10761600) was also significantly negatively associated with susceptibility to CAD (P=0.049). Moreover, these negative disease associations still existed after logistic regression analysis was taken into account to eliminate confounding conventional coronary risk factors. The results implicate possible disease relevance of the polymorphisms in the Mrf-2 gene with susceptibility to CAD. However, a larger scale prospective study is needed to clarify these findings.

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

Background

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

Methods

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

Results

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

Conclusion

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

Pharmacogenomics of Renin Angiotensin System Inhibitors in Coronary Artery Disease

Renin Angiotensin System (RAS) inhibitors comprise some of the most commonly used medications in coronary artery disease (CAD) and its related syndromes. Unfortunately, significant inter-patient variability seems likely in response to these agents; of which, the influence of genetic determinants is of interest. This review summarizes the available RAS inhibitor pharmacogenomic studies which have evaluated RAS polymorphisms that either elucidate mechanism via surrogate endpoint measurements, or predict efficacy via clinical outcomes in CAD related syndromes.Regardless of the endpoint, none of the RAS genotypes conclusively predicts efficacy of RAS inhibitors. In fact, the results of the pharmacogenomic studies were often in direct conflict with one another. Varied results appear due to methodological limitations (e.g., inadequate study power, genotyping error, methods of endpoint measurement), study conceptualization (e.g., overestimating the contribution of polymorphism to disease, lack of haplotype approach), and differences between studies (e.g., genotype frequency, study subject characteristics, the specific medication and dose used). Thus investigators should consider the various methodological limitations to improve upon the current approach to RAS inhibitor pharmacogenomic research in the vast CAD population.

Angiotensin-converting enzyme gene polymorphism and allele frequencies in the lebanese population: prevalence and review of the literature

We studied the distribution of the D/D, I/D, and I/I genotypes of the angiotensin-converting enzyme (ACE) in a sample of healthy Lebanese individuals to assess their prevalence and compare them with other populations. ACE genotypes were determined using the Cardiovascular Disease (CVD) StripAssay, which is based on a Polymerase Chain Reaction-Reverse hybridization technique. DNA from 133 unrelated healthy donors from our HLA-bank was used. The prevalence of D/D, I/D, and I/I genotypes was found to be 39.1, 45.1, and 15.8% respectively, with D and I allelic frequency of 61.7 and 38.3%, respectively. The sampled Lebanese population showed ACE genotypic distributions similar to Caucasians; however, with tendency towards harboring high D allele frequency together with a low I allele frequency just like the Spanish population. This first report from Lebanon will serve as a baseline statistical data for future investigations of the prevalence of ACE genotypes in association with various clinical entities notably cardiovascular diseases. The medical literature was also reviewed in this context.

Angiotensin II type I receptor gene polymorphism: anthropometric and metabolic syndrome traits

BACKGROUND

The renin angiotensin system is important in the regulation of vascular tone and fluid and electrolyte balance. The angiotensin converting enzyme gene (ACE) genotype has been shown to affect exercise response and glucose load response dependent on birth weight. Angiotensin II type I receptor (AGTR1) A1166C has previously been associated with the development of hypertension and coronary disease, but its metabolic effects have not been investigated.

METHOD

AGTR1 A1166C was genotyped by allele specific PCR in 378 individuals from Hertfordshire, UK, who had been characterised for metabolic syndrome traits.

RESULTS

Genotype counts were: AA, 183; AC, 170; CC, 25, consistent with Hardy-Weinberg equilibrium. The CC genotype was associated with significantly lower body mass index (by 1.7 units) in men (p = 0.03), and the same magnitude effect in women with significant lower weight in both genders (p = 0.01), also lower waist circumference and waist-hip ratio (p = 0.01) in men, with a trend for lower waist circumference in women also. Additionally, the CC genotype and/or C allele was associated with lower fasting glucose and insulin, and 30 and 120 min glucose in men (respectively, p = 0.08, 0.04, 0.01, 0.06). Lower means of systolic blood pressure, pulse pressure, cholesterol, and fasting triglyceride were also observed for the CC genotype in both genders though these were not statistically significant.

CONCLUSIONS

The AGTR1 1166 CC genotype appears to predispose to favourable anthropometric and metabolic traits, relative to cardiovascular risk.

Genetic polymorphisms of the renin-angiotensin system in end-stage renal disease

BACKGROUND

End-stage renal disease (ESRD) is a complex phenotype resulting from underlying kidney diseases of different etiologies as well as from environmental and genetic factors. The responsible genes influencing the development and rate of progression to ESRD have yet to be defined. We examined an association of the three renin-angiotensin system (RAS) gene polymorphisms with renal disease and progression to ESRD in dialyzed patients.

METHODS

Genotyping was performed in 745 ESRD patients and 520 control subjects for the angiotensin-converting enzyme (ACE) I/D, angiotensinogen (AGT) M235T and angiotensin II type 1 receptor (AT1R) A1166C gene polymorphisms using polymerase chain reaction and gel analysis.

RESULTS

Allele and genotype frequencies of the ACE polymorphism did not differ significantly between ESRD patients and controls. The patient group showed an increased frequency of the T allele of the AGT polymorphism (P = 0.02) and the C allele and CC genotype of the AT1R polymorphism (P<0.01). There was an association of the AT1R gene polymorphism with the progression of renal disease to end-stage failure. The time from diagnosis to the onset of ESRD was significantly shorter in patients carrying the C allele than in subjects with the homozygous AA genotype (4.7 years vs 12.6 years, P<0.001). The observed effect was not associated with hypertension in studied subjects.

CONCLUSION

The results of our study demonstrate the association between the AT1R A/C polymorphism and renal disease progression. The CC/AC genotype of this polymorphism might serve as a predictor for early ESRD and might be useful in planning therapeutic strategies for individual patients.

Genetic variation in G-protein-coupled receptors – consequences for G-protein-coupled receptors as drug targets

G-protein-coupled receptors (GPCRs), including 'orphan' GPCRs whose natural ligands are unknown, comprise the largest membrane receptor superfamily and are the most commonly used therapeutic targets. GPCR genetic loci harbour numerous variants, such as DNA insertions or deletions and single nucleotide polymorphisms that alter GPCR expression and function, thereby contributing to inter-individual differences in disease susceptibility/progression and drug responses. In this article, the authors review examples of GPCR genetic variants that influence transcription, translation, receptor folding and expression on cell surface (by affecting receptor trafficking, dimerisation, desensitisation/downregulation), or perturb receptor function (by altering ligand binding, G-protein coupling and receptor constitutive activity). In spite of such effects, assessment for genetic variants is not currently applied to the drug development and approval process or in the clinical use of GPCR drugs. Further insights will, the authors believe, alter drug discovery/development, therapeutics and likely provide new GPCR drug targets.

Association between the eNOS (Glu298Asp) and the RAS genes polymorphisms and premature coronary artery disease in a Turkish population

BACKGROUND

The renin-angiotensin system (RAS) and endothelial nitric oxide (NO) affect the pathogenesis of atherosclerosis and prognosis of coronary artery disease (CAD). Previous epidemiologic data suggested that genetic factors are more likely to affect young rather than old people. Our objective was to investigate the association between the polymorphisms of eNOS (Glu298Asp) and the RAS genes and premature CAD in a Turkish population.

METHODS

A total of 115 Turkish patients with premature CAD and 83 controls were included in the study. ACE I/D, AT1R A/C, AGT T/M and eNOS Glu298Asp gene polymorphisms were analysed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP).

RESULTS

It was found that increased premature CAD risk is associated with higher frequencies of the ACE DD [OR: 2.600 (CI 95% 1.395-4.847, p=0.002)], AGT MM [OR=2.407 (CI 95% 1.267-4.573, p=0.007)] and eNOS 894TT [OR=17.000 (CI 95% 3.952-73.125, p<0.001)] genotypes. Carriers of ACE DD+eNOS 894TT (p=0.002), AGT MM+eNOS 894TT (p=0.001), AT1R AA+eNOS 894TT and AT1R non-AA+eNOS 894TT (p=0.002) genotypes were significantly associated with the risk of premature CAD.

CONCLUSIONS

This study indicates a synergistic contribution of RAS genes (ACE I/D, AGT T/M, AT1R T/C) and eNOS Glu298Asp polymorphisms to the development of the premature CAD.