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

Association of Angiotensin-Converting Enzyme Insertion/Deletion Polymorphism with the Risk of Atherosclerosis

AIMS

The objective of this study was to perform a meta-analysis to evaluate the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and susceptibility to atherosclerosis (AS).

METHODS

MEDLINE, EMBASE, and the ISI Web of Science were searched for all eligible published studies concerning the relationship of ACE gene polymorphism with AS without language restrictions. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to evaluate this relationship under different genetic models using meta-analytic methods.

RESULTS

A total of 15 articles (16 studies) were involved in this meta-analysis. The D allele of the ACE gene had a nonsignificant increase in the risk of AS (D versus I: OR = 1.23, 95% CI, .98-1.53, P = .07; I² = 87.2%, P_{heterogeneity} < .01). Compared with the II genotype, the DI (relative risk [RR]: 1.35, 95% CI: 1.09, 1.67, P < .01; I² = 47.8%, P_{heterogeneity} = .017) and (DD + DI) (RR = 1.38, 95% CI: 1.04, 1.82, P = .02; I² = 73.3%, P_{heterogeneity} < .01) genotype of ACE was associated with higher risk of AS, respectively. Subjects with the DD genotype showed a statistically nonsignificant trend toward greater risk of AS (RR = 1.53, 95% CI: .97, 2.43, P = .07; I² = 88.6%, P_{heterogeneity} < .01). Further subgroup analyses showed that significant relationships were only found in Europeans under different gene polymorphism or different genotype models rather than Asians.

CONCLUSIONS

The present meta-analysis indicated that the D allele in the ACE gene was associated with the risk of AS, especially in Europeans. Furthermore, increased copy number of D allele was significantly associated with increased AS risk in a dose-dependent manner.

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.

Polymorphism of the angiotensin-converting enzyme (ACE) and angiotesinogen (AGT) genes and their associations with blood pressure and carotid artery intima media thickness among healthy Finnish young adults--the Cardiovascular Risk in Young Finns Study

The roles of angiotensin converting enzyme (ACE) insertion-deletion (I/D) and angiotensinogen (AGT) m235t polymorphisms in cardiovascular diseases have been investigated extensively during the past decade but results have been inconsistent. A sex-specific association between the ACE I/D polymorphism and systolic blood pressure (BP) was seen among Finnish children and adolescents previously. We investigated if these polymorphisms associate with the BP and carotid artery intima media thickness (IMT) in the same cohort during their adulthood. IMT data were available for 224 ACE I/D genotyped individuals and 202 AGT m235t genotyped individuals. Systolic and diastolic blood pressure values did not differ between ACE and AGT genotypes. Age and BMI adjusted mean IMT was 0.02 (95% CI: -0.05 to 0.02, p=0.33) and 0.03 mm (95% CI: -0.07 to 0.001, p=0.06) lower among the ID and DD genotype groups, respectively, compared to the II genotype group. MT and TT genotype groups had 0.02 mm (95% CI: -0.01 to 0.05, p=0.17) higher and 0.01 mm (95% CI: -0.04 to 0.02, p=0.59) lower mean IMT, respectively, compared to the MM genotype group. We conclude that ACE I/D and AGT m235t polymorphisms are not associated with carotid IMT in healthy young Finnish adults.

Angiotensinogen and Plasminogen Activator Inhibitor-1 Gene Polymorphism in Relation to Renovascular Disease

The present study was designed to evaluate angiotensinogen (AGT) M235T and plasminogen activator inhibitor-1 (PAI-1) (4G/5G) polymorphisims in relation to the occurrence of atherosclerotic renal artery stenosis (ARAS) and recurrent stenosis. In this study, 30 patients were enrolled after angiographic demonstration of ARAS; 100 healthy subjects for AGT polymorphism and 80 healthy subjects for PAI-1 polymorphism were considered the control group. The patients were followed for a mean 46.1 +/- 9.2 months. The patients had significantly higher frequencies of the MT genotype and the T allele than control group (chi(2) = 18.2, p < 0.001 and chi(2) = 11.5 p < 0.001). There were no significant differences in the PAI-1 genotype and allele findings when the data for all patients were compared with that for the controls (chi(2)= 2.45, p = 0.29 and chi(2) = 0.019, p = 0.89). There were no significant differences in the genotype and allele findings for the patients with and without restenosis (p > 0.05). The C-reactive protein (CRP) level was higher in the patients with restenosis than in the patients without restenosis (7.694 +/- 0.39 mg/L and 1.56 +/- 1.08 mg/L) (p = 0.001). Our results suggest that the M235T MT genotype and T allele might be associated with increased risk of atherosclerotic renal artery stenosis. The CRP level might be an independent predictor for recurrent stenosis.

Angiotensinogen and plasminogen activator inhibitor-1 gene polymorphism in relation to chronic allograft dysfunction*

Chronic allograft dysfunction (CAD) is the most common cause of allograft failure in the long-term, and current immunologic strategies have little effect on this condition. The renin-angiotensin system (RAS) plays important roles progression of chronic renal disease. It is thought that plasminogen activator inhibitor-1 (PAI-1) functions in the RAS, in addition to involvement in thrombotic risk and fibrosis. This study investigated possible links between angiotensinogen (AGT) genotypes (M235T/MM, MT, TT) and PAI-1 genotypes (4G4G, 4G5G, 5G5G) and CAD assessments of both types of polymorphism were performed in 82 renal allograft recipients. One hundred healthy subjects were also investigated for AGT polymorphism, and 80 healthy subjects for PAI-1 polymorphism. Genotypes were determined using polymerase chain reaction (PCR) sequence-specific primers, and PCR followed by restriction fragment length polymorphism analysis. Kidney recipients with CAD had significantly lower frequencies of the MM genotype and the M allele than the recipients without CAD (p < 0.05 and <0.001). The transplant recipients with CAD also had significantly lower frequencies of the 5G5G genotype and the 5G allele than those without CAD (p < 0.001 and <0.05). Determination of AGT M235T and PAI-1 genotypes prior to transplantation may help identify patients who at risk for chronic renal transplant dysfunction.

Renovascular disease: effect of ACE gene deletion polymorphism and endovascular revascularization

BACKGROUND

Renal artery stenosis (RAS) is associated with high cardiovascular mortality and significant clinical complications, including resistant hypertension and ischemic nephropathy. Despite availability of endovascular revascularization techniques, determining which patients should undergo revascularization and the timing of the procedure still are controversial. Several studies have reported a higher frequency of the DD genotype of the insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene in patients with RAS, and one study found higher mortality in patients with the DD genotype. Material and methods We retrospectively studied 100 patients with documented atherosclerotic RAS and evaluated long-term (median follow-up, 28 months) mortality, blood pressure control, and renal function in relation to the ACE genotype and two therapeutic strategies, that is, endovascular treatment with percutaneous renal transluminal angioplasty or stenting (ET group) versus conservative drug therapy (CT group).

RESULTS

Comparison between therapeutic groups showed a higher cumulative probability of survival (86.7% vs 67.1%), better blood pressure control (57.4% vs 29%), and slower decline in renal function (17.9% vs 48.4%) in the ET group. The DD genotype was strongly represented in our study patients (DD, 50%; II, 15.5%; I/D, 34.5%), but bore no relation to mortality, blood pressure control, decline in renal function, or rate of recurrent stenosis.

CONCLUSIONS

Conservative medical treatment of RAS, compared with endovascular treatment, is associated with higher mortality, poorer blood pressure control, and impaired renal function over the long term. Early endovascular treatment enables amelioration of this unfavorable evolution. The DD genotype does not predict clinical outcome of RAS.

Different impact of deletion polymorphism of gene on the risk of renal and coronary artery disease

OBJECTIVE

An increased frequency of the angiotensin converting enzyme (ACE) D variant has recently been reported in patients with atheromatous renal artery disease (RAD), whereas controversy exists on the risk of coronary artery disease (CAD) associated with this polymorphism. In spite of the frequent coexistence of RAD and CAD, no studies have specifically compared ACE insertion/deletion (I/D) polymorphism in patients with coronary versus renal artery disease or defined the risk of each disease associated with the D variant.

DESIGN

We designed a large case-control study of subjects for whom objective renal or coronary angiographic documentation was available.

METHODS AND RESULTS

We analysed ACE I/D genotype and clinical-biochemical data of a total of 942 subjects (123 patients with and 137 without angiographic evidence of RAD, 420 patients with and 262 without angiographic evidence of CAD). Renal (with and without RAD) and coronary patients were similar for most conventional risk factors. There was no difference in DD frequency between CAD and CAD-free patients (38.1 versus 33.6%, NS) and DD homozygosity was not associated with CAD risk (OR = 1.27, 95% CI = 0.82-1.98). In contrast, the DD genotype was more frequent in RAD than in RAD-free patients (54.5 versus 39.4, P < 0.05) and was associated with a 2.25-fold increased risk of RAD in both the univariate and multivariate logistic regression models. Additional predictors of RAD were age and creatinine. In RAD/RAD-free patients with angiographically documented CAD, DD homozygosity was confirmed to be preferentially associated with RAD (P < 0.05).

CONCLUSIONS

ACE D variant is preferentially associated with atherosclerotic renal rather than with coronary disease, despite similar exposure to atherogenic noxae. DD homozygosity confers a 2.25-fold increased risk of RAD.