Genetic risk for renal artery stenosis: association with deletion polymorphism in angiotensin 1-converting enzyme gene

ACE I/D genotype associates with strength in sarcopenic men but not with response to ACE inhibitor therapy in older adults with sarcopenia: Results from the LACE trial

BACKGROUND

Angiotensin II (AII), has been suggested to promote muscle loss. Reducing AII synthesis, by inhibiting angiotensin converting enzyme (ACE) activity has been proposed as a method to inhibit muscle loss. The LACE clinical trial was designed to determine whether ACE inhibition would reduce further muscle loss in individuals with sarcopenia but suffered from low recruitment and returned a negative result. Polymorphic variation in the ACE promoter (I/D alleles) has been associated with differences in ACE activity and muscle physiology in a range of clinical conditions. This aim of this analysis was to determine whether I/D polymorphic variation is associated with muscle mass, strength, in sarcopenia or contributed to the lack of response to treatment in the LACE study.

METHODS

Sarcopenic individuals were recruited into a 2x2 factorial multicentre double-blind study of the effects of perindopril and/or leucine versus placebo on physical performance and muscle mass. DNA extracted from blood samples (n = 130 72 women and 58 men) was genotyped by PCR for the ACE I/D polymorphism. Genotypes were then compared with body composition measured by DXA, hand grip and quadriceps strength before and after 12 months' treatment with leucine and/or perindopril in a cross-sectional analysis of the influence of genotype on these variables.

RESULTS

Allele frequencies for the normal UK population were extracted from 13 previous studies (I = 0.473, D = 0.527). In the LACE cohort the D allele was over-represented (I = 0.412, D = 0.588, p = 0.046). This over-representation was present in men (I = 0.353, D = 0.647, p = 0.010) but not women (I = 0.458, D = 0.532, p = 0.708). In men but not women, individuals with the I allele had greater leg strength (II/ID = 18.00 kg (14.50, 21.60) vs DD = 13.20 kg (10.50, 15.90), p = 0.028). Over the 12 months individuals with the DD genotype increased in quadriceps strength but those with the II or ID genotype did not. Perindopril did not increase muscle strength or mass in any polymorphism group relative to placebo.

CONCLUSION

Our results suggest that although ACE genotype was not associated with response to ACE inhibitor therapy in the LACE trial population, sarcopenic men with the ACE DD genotype may be weaker than those with the ACE I/D or II genotype.

An Outline of Renal Artery Stenosis Pathophysiology-A Narrative Review

Renal artery stenosis (RAS) is conditioned mainly by two disturbances: fibromuscular dysplasia or atherosclerosis of the renal artery. RAS is an example of renovascular disease, with complex pathophysiology and consequences. There are multiple pathophysiological mechanisms triggered in response to significant renal artery stenosis, including disturbances within endothelin, kinin-kallikrein and sympathetic nervous systems, with angiotensin II and the renin-angiotensin-aldosterone system (RAAS) playing a central and key role in the pathogenesis of RAS. The increased oxidative stress and the release of pro-inflammatory mediators contributing to pathological tissue remodelling and renal fibrosis are also important pathogenetic elements of RAS. This review briefly summarises these pathophysiological issues, focusing on renovascular hypertension and ischemic nephropathy as major clinical manifestations of RAS. The activation of RAAS and its haemodynamic consequences is the primary and key element in the pathophysiological cascade triggered in response to renal artery stenosis. However, the pathomechanism of RAS is more complex and also includes other disturbances that ultimately contribute to the development of the diseases mentioned above. To sum up, RAS is characterised by different clinical pictures, including asymptomatic disorders diagnosed in kidney imaging, renovascular hypertension, usually characterised by severe course, and chronic ischemic nephropathy, described by pathological remodelling of kidney tissue, ultimately leading to kidney injury and chronic kidney disease.

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.

Lack of an association between angiotensin converting enzyme gene polymorphism and peripheral arterial occlusive disease

Numerous factors have been reported to influence the pathogenesis of atherosclerosis. The angiotensin I converting enzyme (ACE) gene is a candidate gene for atherosclerotic-related disease. In the present study, the association between the polymorphism of the ACE gene and peripheral arterial occlusive disease (PAOD) was investigated. Using polymerase chain reaction techniques, 100 patients (age 66.7-7.7 years) with PAOD and 100 age-matched controls were divided into the three ACE genotypes: II, ID and DD (Insertion I and Deletion D). There was no evidence of any association between ACE gene polymorphism and the presence of PAOD (odds ratio 0.759; 95% confidence interval 0.418-1.377). These results indicate an absence of association between DD genotype and PAOD. Further evaluation in a larger population study is required to examine the possibility of an increased risk of PAOD in DD homozygotes.

Gene therapy--why can it fail?

The success of reductionism in medicine has enabled the experimental expression of individual genes in complex living systems. The promise of gene therapy, permanent reversal or amelioration of disease symptoms without dependence on a long-lasting intake of drugs, has come within reach because of these conceptual and technical advances in molecular biology. However, there have been setbacks posing serious questions for the medical community. The incidents came at a time when technical advances in the manipulation of DNA had led to wide-spread testing of gene based therapies. In fact, the major limiting factor of this approach had been perceived to be gene delivery rather than toxicity. Here we discuss the hypothesis that knowledge of DNA sequences for relevant genes alone will not be sufficient to allow this promise to come to fruition, unless additional factors are recognized and addressed. The physiologic consequences of gene expression depend on gene dosage, transcriptional regulation by promoters, posttranscriptional editing, and interdependence among gene products, all of which vary among cells. The success of gene therapy will depend, in part, on insight into the factors summarized here, very much like successful drug therapy has depended on an understanding of the manifold influences of pharmacokinetics and pharmacodynamics. In principle, these considerations apply to all transfections, gene disruptions, and transgenic approaches and to potential clinical applications derived from them. Gaining insight and control over those factors may allow gene therapy to live up to current expectations.

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

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

Cardiovascular risk factor treatment targets and renal complications in high risk vascular patients: a cohort study

BACKGROUND

To determine if recommended treatment targets, as specified in clinical practice guidelines for the management of cardiovascular disease, reduces the risk of renal complications in high risk patient populations.

METHODS

This was a cohort study. Participants in Utrecht, The Netherlands either at risk of, or had cardiovascular disease were recruited. Cardiovascular treatment targets were achievement of control in systolic and diastolic blood pressure, total and low-density cholesterol, and treatment of albuminuria. Outcome measures were time to development of end stage renal failure or symptomatic renal atherosclerotic disease requiring intervention.

RESULTS

The cohort consisted of 7,208 participants; 1,759 diabetics and 4,859 with clinically manifest vascular disease. The median age was 57 years and 67% were male. Overall, 29% of the cohort achieved the treatment target for systolic blood pressure, 39% for diastolic blood pressure, 28% for total cholesterol, 31% for LDL cholesterol and 78% for albuminuria. The incidence rate for end stage renal failure and renal atherosclerotic disease reduced linearly with each additional treatment target achieved (p value less than 0.001). Achievement of any two treatment targets reduced the risk of renal complications, hazard ratio 0.46 (95% CI 0.26-0.82). For patients with clinically manifest vascular disease and diabetes, the hazard ratios were 0.56 (95% CI 0.28 - 1.12) and 0.28 (95%CI 0.10 - 0.79) respectively.

CONCLUSION

Clinical guidelines for cardiovascular disease management do reduce risk of renal complications in high risk patients. Benefits are seen with attainment of any two treatment targets.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Genetic Risk of Atherosclerotic Renal Artery Disease

It is largely unknown to what extent genetic abnormalities contribute to the development of atherosclerotic renal artery disease. Among the potential candidate genes, those of the renin-angiotensin system and the endothelial nitric oxide synthase (eNOS) rank high because of their importance in the atherosclerotic process. We investigated the association of polymorphisms in these genes (the angiotensinogen Met235Thr, the angiotensin-converting enzyme insertion/deletion, the angiotensin II type-1 receptor A1166C, and the eNOS Glu298Asp) with the presence or absence of atherosclerotic renovascular disease in 456 consecutive hypertensive patients referred for renal angiography on the suspicion of renovascular hypertension. Nondiseased normotensive (n=200) and hypertensive (n=154) patients from a family practice served as external controls. Renal artery disease was present in 30% of our angiography group. The Asp allele of the eNOS Glu298Asp polymorphism was associated with atherosclerotic renal artery stenosis with an odds ratio of 1.44 (95% confidence interval 1.00 to 2.09) versus hypertensives with angiographically proven patent arteries, of 1.89 (1.24 to 2.87) versus hypertensive family practice controls, and of 2.09 (1.29 to 3.38) versus normotensive family practice controls. However, this allele also differed significantly between patients with patent renal arteries and normotensive and hypertensive controls. No differences were found with respect to the other genetic polymorphisms. We hypothesize that the Asp allele of the Glu298Asp polymorphism may predispose to the development of atherosclerotic lesions but that renal artery involvement depends on other factors, also.

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.

I/D ACE gene polymorphism in survival of leukemia patients -- hypothesis and pilot study

Angiotensin-I converting enzyme (ACE) is involved not only in intracellular volume regulation but also in proliferation control. Since both ACE gene polymorphism (I/D ACE) and ABO blood group determine ACE level in peripheral blood and probably also in bone marrow, the hypothesis to the interindividual differences in survival of leukemic patients was suggested. The data of 25 patients of both sexes with acute myelogenous (AML), acute lymphatic (ALL), chronic myelogenous (CML) and chronic lymphatic (CLL) leukemia treated by conventional were used for the study. The overall survival (SUR) was estimated as the time from the date of diagnosis to the date of death. The difference between patient's individual SUR (iSUR) and median SUR according to the type of leukemia (mSUR) was calculated. This difference (iSUR-mSUR) varied with I/D ACE genotype (p<0.02) but neither with diagnosis nor with ABO blood group. The regression model for iSUR calculation, from mSUR and I/D ACE genotype, has been suggested.

Disease of proximal part of vertebral artery in patients with coronary artery disease

Recognition of coincidence of cerebral vascular disease is of importance in patients with coronary artery disease. One hundred and seventy-three patients who underwent coronary angiography were also studied by angiography of subclavian arteries and abdominal aorta. The majority of the patients (128/173; 74%) were men. Risk factors of hypertension, diabetes, and hypercholesterolemia were present in a high percentage of patients. Disease of the proximal part of the vertebral artery was seen in 41.6% (72/173). Presence of vertebral artery disease was significantly correlated with diabetes (p = 0.02), renal artery stenosis (p = 0.003), coronary artery disease (p = 0.05), and iliac artery disease (p = 0.05). The proximal part of the vertebral artery was found to be affected in a high percentage (41.6%) of patients undergoing coronary angiography.

Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Prior to 1993, most drug efficacy and safety trials were conducted in white males, although gender and racial differences in pharmacodynamics and pharmacokinetics have been documented since the early 1900s. Over the last 2 decades, supported by the FDA and legislation, attempts to include more women and minorities in clinical drug trials have been made, with limited success. Yet, there are important differences in pathophysiology and pharmacogenetics, as well as pharmacotherapeutic effectiveness. This is the first of 2 articles that review the basic scientific principles of such differences. In particular, genetic polymorphisms of cardiovascular candidate genes and drug metabolism are described. The pharmacodynamic and pharmacokinetic variations among genders and ethnicities are summarized.

Angiotensin-converting enzyme gene polymorphism and vascular manifestations in Korean patients with SLE

Systemic lupus erythematosus (SLE) is an inflammatory multisystem disease of unknown etiology with immunologic aberrations. Many studies have shown that genetic and environmental factors are implicated in the development of SLE. Angiotensin-converting enzyme (ACE) affects various immune phenomena through the renin-angiotensin and kallikrein-kininogen systems by creating angiotensin II and inactivating bradykinin. We investigated the correlation between insertion/ deletion polymorphism of the ACE gene and the clinical manifestations of SLE, especially vascular involvement and lupus nephritis. Two-hundred and eleven Korean patients fulfilling the ACR criteria and 114 healthy subjects were enrolled. The ACE genotype was determined by polymerase chain reaction using genomic DNA from peripheral blood. The nephritis patients were classified by the WHO classification. In addition, the activity and chronicity index were used to assess the severity of renal involvement. We evaluated vascular involvement by the presence or absence of hypertension, Raynaud's phenomenon, livedo reticularis, antineutrophil cytoplasmic antibody and the SLICC/ACR Damage Index. The gene frequency of ACE gene polymorphism was as follows: II 39 vs 34%, ID 41 vs 50%, DD 20 vs 16% in SLE patients and controls, respectively. There was no difference in genotype frequency between both groups. There were no significant differences between the distribution of ACE gene genotypes and lupus nephritis and its related parameters, including WHO classification, activity index, chronicity index, renal dysfunction and amount of 24 h urinary protein. The ACE genotypes and alleles did not affect the presence of vascular manifestations evaluated, but the frequency of DD genotype was significantly low in SLE patients with Raynaud's phenomenon compared to those without Raynaud's phenomenon (P = 0.002 for ACE ID vs DD and II, OR 2.7, 95% CI 1.43-5.09; P=0.023 for ACE DD vs ID and II, OR 0.33, 95% CI 0.12-0.89). Also skewing from DD to II genotype was noted in patients with anti-Sm antibody compared to those without anti-Sm antibody (P = 0.025 for ACE DD vs ID and II, OR 0.21, 95% CI 0.05-0.93). The onset age of serositis was older in patients with the ID genotype than the others (ID= 34.5+/-10.8, II + DD = 25.6+/-10.2, P= 0.002). Also the onset age of malar rash was older in patients with II genotype than the others (II=26.7+/-8.4, ID+DD=21.3+/-9.0; P=0.021). The patients with I allele showed a significantly higher frequency of serositis (P = 0.022). Taken together, the I/D polymorphisms of ACE gene did not affect susceptibility of SLE, lupus nephritis and the vascular manifestations, including Raynaud's phenomenon, in Korean SLE patients, although the DD genotype was negatively associated with Raynaud's phenomenon among SLE patients. However, it would be valuable to evaluate the role of other genes potentially related to vascular events, such as endothelin, nitric oxide or angiotensin II receptor as well as ACE gene.

Extent and severity of atherosclerotic vascular disease in patients undergoing coronary angiography--the Kuwait Vascular Study

Only a few angiographic studies have correlated the presence and severity of coronary artery disease with atherosclerosis in other arteries. The presence of disease in more than 1 area clearly has important implications on management. One hundred and seventy eight patients had angiographic evaluation of their peripheral arteries and abdominal aorta after routine diagnostic coronary angiography. The extent and severity of vascular disease was correlated with those of coronary artery disease. Of the 178 patients, 73.6% were men (mean age +/- sd was 52.93 +/- 10.12 years). Hypercholesterolemia (59%), systemic hypertension (56.7%) and diabetes mellitus (50.6%) were the major risk factors. Triple-vessel coronary artery disease was present in 48.9%, and 13.5% had normal coronaries. A new atherosclerotic vascular disease score, which reflects the presence and severity of atherosclerotic vascular disease elsewhere, was seen to correlate significantly with the extent of coronary artery disease. Of particular interest was the involvement of the first part of the vertebral artery in 41.6% of patients. The combined involvement of the abdominal aorta, renal artery, and iliac artery segments (together referred to as the lower body segment) was seen almost exclusively in those with 2- or 3-vessel coronary artery disease. Also there was a direct correlation between the extent of coronary artery disease and the score in the lower body segment as opposed to the upper body segment (subclavian, vertebral, and internal mammary arteries). The presence of atherosclerotic vascular disease correlated with the severity of coronary artery disease, particularly in respect to disease in the lower body segment. Thus early detection of such disease in the iliac or femoral arteries has a potential for early diagnosis of significant coronary artery disease.

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

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

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.

Lack of association of ACE/angiotensinogen genotype with renal function in autosomal dominant polycystic kidney disease

ACE polymorphisms have recently been shown to associate with worse renal and or cardiovascular outcome, with the D allele widely reported as a risk factor for cardiovascular disease. In autosomal dominant polycystic kidney disease (ADPKD), there are conflicting reports of an association between ACE polymorphisms and disease phenotype. There are no previous reports of any association between angiotensinogen polymorphisms and clinical phenotype in ADPKD. We examined the ACE I/D and angiotensinogen M235T polymorphisms in 176 patients with ADPKD. Patients are categorized into three groups according to the reason for initial investigation. Clinical history and examination findings were recorded at the time of first referral. A cohort of 17 patients had progressive renal impairment observed after 3 or more years of follow-up. Reciprocal creatinine against time was plotted in this group. From the patient population of 176, a total of 33 patients reached end-stage renal failure (ESRF) or a serum creatinine greater than 500 microm/liter. ACE genotype and M235T polymorphism frequencies were compared across groups. Serum creatinine and presence of hypertension and onset of ESRF were taken as outcome variables; age and source of referral were taken as confounding variables. There was no association of any genotype or allele with either creatinine, inverse creatinine, hypertension, or age at end-stage renal failure. These findings do not support the proposition that ACE genotype or angiotensinogen polymorphisms are associated with a worse prognosis in patients with ADPKD.

What can knockout mice contribute to an understanding of hypertension?

The generation of knockout mice using homologous recombination in embryonic stem cells is a powerful tool for physiologic investigations. This experimental approach has provided unique insights into the study of hypertension. Studies using knockout mice have shed new light on blood pressure regulatory mechanisms, molecular mechanisms of end-organ injury, and genetic mechanisms for hypertension. With the development of more accessible approaches for carrying out sophisticated manipulation of the mouse genome, there will be continuing utility of this technique for future studies of hypertension.

ACE gene polymorphism and survival in atherosclerotic renovascular disease

Renovascular disease (RVD) is an important cause of end-stage renal disease and is associated with a high mortality rate, mostly because of coexisting cardiovascular and cerebrovascular disease. The deletion (DD) polymorphism of the angiotensin-converting enzyme (ACE) gene has been described in association with severe vascular disease affecting major organs. To investigate whether DD genotype is a risk factor for mortality in RVD, we performed a follow-up study of 61 patients with this disease. Patients (age, 68.0 +/- 6.5 years) affected by atherosclerotic vascular disease were enrolled after angiographic demonstration of a renal artery stenosis. The average follow-up was 48.1 +/- 14.9 months. Genotype was insertion/deletion (I/D) in 30 patients, DD in 27 patients, and II in 4 patients. At enrollment, a complete assessment of heart, blood vessels, and renal function was performed. During the follow-up period, 13 patients died (9 DD, 4 ID) and 7 patients evolved into end-stage renal failure. The cumulative survival rate at 5 years was 45.4% +/- 13.4%. Factors associated with mortality were analyzed with Cox proportional hazard regression. The multivariate analysis showed that DD genotype, severe carotid disease, and smoking were independent predictors of mortality. The multivariate analysis of predictors of renal failure showed that the only significant association was found with baseline serum creatinine level of 265 micromol/L or greater. We conclude that the DD genotype of the ACE gene is a marker for mortality in RVD.

Analysis of the insertion/deletion polymorphism of the human angiotensin converting enzyme (ACE) gene in patients with renal cancer

The angiotensin I-converting enzyme (ACE) contains an insertion/deletion (I/D) polymorphism, with the DD genotype associated with benign renal diseases. The distribution frequencies of the D and I alleles, and the DD, DI and II genotypes were determined in DNA extracted from kidney tissues of 58 renal cancer patients. The observed frequencies in patients who develop renal cancer was not significantly different than the normal population.

Angiotensin-converting enzyme gene I/D polymorphism and carotid artery disease in renovascular hypertension

There is evidence linking the activation of the renin-angiotensin system (RAS) with target organ damage in renovascular hypertension (RVH). A genetic association of the DD genotype of the angiotensin-converting enzyme (ACE) gene with cardiovascular complications has been found in various clinical conditions. The aim of our study was to determine whether the insertion/deletion (I/D) polymorphism of the ACE gene is associated with the high prevalence of target organ damage reported in RVH. A total of 65 atherosclerotic patients (age 68.2 +/- 5.2 years) with RVH and 49 atherosclerotic patients (age 68.0 +/- 6.3 years) with essential hypertension (EH) were sequentially enrolled when attending the outpatient clinic for specialist assessment of their vascular disorder. Cardiac, renal, and vascular involvement were assessed in both groups and blood was taken for genetic analysis. Patients with RVH had a higher prevalence of left ventricular hypertrophy (LVH), carotid artery disease, and albuminuria than those with EH. In RVH, but not in EH, the DD genotype was significantly associated with severe arterial disease. In RVH, carotid disease (lumen narrowing >60%) was present in 62% of DD patients versus 25% of the other genotypes (OR = 4.90, 95% CI: 1.70-14.13). Such an association was also present in peripheral vascular disease: 72.4% in DD patients versus 41.6% in the other genotypes (OR = 3.67, 95% CI = 1.29-10.36). Logistic regression analysis showed that the DD genotype was the strongest predictor of risk of severe carotid disease. We conclude that, in atherosclerotic RVH, there is an association of the severity of vascular disease with the DD genotype of the ACE gene.

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

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

Relationship between the apolipoprotein E and angiotensin-converting enzyme genotypes and LDL particle size in Japanese subjects

We investigated whether the apolipoprotein E (apoE) and the angiotensin-converting enzyme (ACE) genotypes contribute to the variance in low-density lipoprotein (LDL) particle size in Japanese subjects (n = 136; M/F= 106/30). ACE polymorphism was associated with neither LDL size nor individual lipid levels. In contrast, the subjects with the epsilon2 allele of the apoE genotype had significantly lower levels of total cholesterol (P = 0.002) and LDL cholesterol (P = 0.004) compared with those without the epsilon2 allele. The subjects with the epsilon4 allele had a significantly smaller LDL particle size than those without the epsilon4 allele (P = 0.012). Separate analyses of the male subjects showed similar associations. A stepwise regression analysis revealed the epsilon4 allele to be an independent contributing variable that could affect LDL particle size. Our results suggest that the apoE genotype is associated with the development of atherosclerotic disease, since the epsilon2 and epsilon4 alleles relate to a decrease in LDL cholesterol levels and a decrease in LDL particle size, respectively.

Lack of c-kit mutation in familial urticaria pigmentosa

Somatic mutations within c-kit have been reported in individuals with mastocytoses, including urticaria pigmentosa (UP). We have identified three siblings with UP. We aimed to determine whether the c-kit proto-oncogene was playing a part in the aetiology of UP in these three siblings. Using seven microsatellite repeat markers spanning an 8-cM interval encompassing the c-kit gene we followed the transmission of the c-kit gene in this family. Furthermore, single-strand conformation polymorphism analysis was used to scan exon 17 of the c-kit gene for mutations in genomic DNA of all family members and somatic DNA extracted from skin of the eldest affected sibling, the proband. No mutations were found in exon 17 in either genomic DNA of all family members or somatic DNA of the proband. Patients with UP have been shown to possess somatic mutations of the c-kit gene. However, this locus has been excluded as playing a part in the three siblings examined here in whom a second gene locus must be determining their UP. Therefore, this study emphasizes genetic heterogeneity in UP. Future study to identify primary molecular determinants of UP should include affected sib-pair studies.

Insertion/deletion angiotensin converting enzyme gene polymorphism affects the microvascular structure of the kidney in patients with nondiabetic renal disease

OBJECTIVE

It has been reported that the deletion allele of the insertion/deletion polymorphism of the angiotensin I converting enzyme gene is associated with increased cardiovascular risk and progressive renal disease, including immunoglobulin A nephropathy. We therefore investigated the relationship between angiotensin converting enzyme polymorphism and intrarenal microvascular structure in 56 patients with nondiabetic renal disease.

METHODS AND RESULTS

We determined various cardiovascular hormones of the renin-angiotensin system and angiotensin converting enzyme gene polymorphism in 56 patients with nondiabetic renal diseases who underwent a renal biopsy. The patients were divided into three groups by angiotensin converting enzyme genotype (insertion/insertion, n = 21; insertion/deletion, n = 23; deletion/deletion, n = 12) using polymerase chain reaction methods. The angiotensin converting enzyme insertion/ deletion and deletion/deletion genotypes were associated with a significantly higher interlobular artery wall : lumen ratio than the insertion/insertion genotype (insertion/insertion 0.27 +/- 0.01, insertion/deletion 0.32 +/- 0.01, deletion/deletion 0.33 +/- 0.02; P < 0.05). Afferent arteriolar and tubulo-interstitial injury scores were similar among the three genotypes. Although serum angiotensin converting enzyme activity was higher in the deletion/deletion than in the other two genotypes (insertion/insertion 9.7 +/- 0.7, insertion/deletion 10.7 +/- 0.9, deletion/deletion 14.0 +/- 2.4 IU/I; P < 0.05), other factors of the renin-angiotensin system, including blood pressure and serum creatinine levels, were not different among the three groups.

CONCLUSIONS

The angiotensin converting enzyme deletion/deletion genotype may be considered a risk factor for the development of microvascular wall thickening in nondiabetic renal diseases.

Renin-angiotensin system gene polymorphisms and left ventricular hypertrophy. The case against an association

There is accumulating evidence for association between genetic polymorphisms of components of the renin angiotensin system (RAS), especially angiotensin-converting enzyme (ACE), and cardiovascular disease. However, there is lack of agreement that the ACE polymorphism is associated with left ventricular hypertrophy (LVH) in hypertension. A possible paradigm for the development of LVH involves the ACE gene polymorphism influencing cardiac mass by an action on plasma and/or tissue levels of angiotensin II. Such a model has experimental support and provides the basis for examining the lack of agreement between studies. The finding of lack of association between RAS gene polymorphism and LVH may be due to methodological problems, differences in genetic background between populations, interactions between genetic variants of RAS components or to the model being inappropriate. Low predictability of ACE genotype markers for LVH together with conflicting reports on the influence of RAS genetic variants on angiotensin II production suggests that the simple RAS paradigm may not apply for hypertension. Further information on the nature of the link between the ACE polymorphism and ACE regulation as well as the relation between the RAS and pathophysiology of LVH is needed. At present there is insufficient evidence to accept ACE gene polymorphism as a susceptibility marker for LVH.

The deletion/insertion polymorphism of the angiotensin converting enzyme gene and cardiovascular-renal risk

OBJECTIVE

This meta-analysis attempted to derive pooled estimates for the associations between various cardiovascular-renal disorders and the deletion/insertion (D/I) polymorphism of the angiotensin converting enzyme (ACE) gene.

METHODS

Case-control studies were combined, using the Mantel-Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the within-study mean of the II genotype as the denominator.

RESULTS

The computerized database used for this analysis included 145 reports with an overall sample size of 49 959 subjects. Overall, possession of the D allele was associated with an increased risk of atherosclerotic and renal microvascular complications. In comparison with the II reference group, the excess risk in DD homozygotes (P < 0.001) was 32% for coronary heart disease (CHD; 30 studies), 45% for myocardial infarction (20 studies), 94% for stroke (five studies) and 56% for diabetic nephropathy (11 studies). The corresponding risk in DI heterozygotes amounted to 11% (P= 0.02), 13% (P= 0.02), 22% (P= 0.10) and 40% (P < 0.001), respectively. Hypertension (23 studies), left ventricular hypertrophy (five studies), hypertrophic or dilated cardiomyopathy (eight studies) and diabetic retinopathy (two studies) were not related to the DI polymorphism. Publication bias was observed for CHD, myocardial infarction and microvascular nephropathy, but not hypertension. In studies with DNA amplification in the presence of insertion-specific primers, the risk associated with the DD genotype increased to 150% [95% confidence interval (CI) 76-256; four studies] for diabetic nephropathy, but decreased to 12% (95% CI -3 to 28; seven studies) for CHD and 14% (95% CI -6 to 37; four studies) for myocardial infarction. On the other hand, the pooled odds ratios did not materially change if the meta-analysis was limited to articles published in journals with an impact factor of at least 4. Furthermore, compared with the II control group, the circulating ACE levels (29 studies) were raised 58 and 31% (P < 0.001) in DD and DI subjects, respectively. In contrast, plasma renin (10 studies), systolic and diastolic blood pressure (46 studies) and body mass index (30 studies) were not associated with the D allele.

CONCLUSION

The D allele is not associated with hypertension, but behaves as a marker of atherosclerotic cardiovascular complications and diabetic nephropathy. These associations do not necessarily imply a causal relationship and may have been inflated by publication bias. Nevertheless, their possible therapeutic implications may be subject to further investigation in prospective (intervention) studies.

Angiotensin-converting enzyme gene I/D polymorphism and carotid plaques in Japanese

To clarify the role of genetic factors in atherosclerotic plaque formation in the carotid artery and magnetic resonance imaging abnormalities in the brain, we investigated the association of these abnormalities with the angiotensin-converting enzyme (ACE) genotype. One hundred sixty-nine subjects (age, 59.2+/-0.8 years, mean+/-SE) admitted to our hospital for health checkups underwent brain magnetic resonance imaging to evaluate lacunar infarction. B-mode ultrasound examinations of the carotid arteries were performed to detect atherosclerotic plaque. The I/D polymorphism of the ACE gene was determined by the polymerase chain reaction method. Multivariate regression analysis was performed to assess the effects of the following variables on the presence of plaque, mean plaque thickness, and number of plaques: fibrinogen, sex, age, body mass index, mean blood pressure, glycosylated hemoglobin, LDL cholesterol, HDL cholesterol, hematocrit, and the D allele of the ACE gene. The frequency of carotid atherosclerotic plaque was significantly (P=.034) higher in subjects with the D allele than in those without this allele. However, the frequency of lacunar stroke was similar in these groups. A multivariate regression analysis showed that the presence of plaque was independently associated with the D allele (odds ratio=3.27, P=.016). However, mean plaque thickness and the number of plaques were not associated with the D allele. The D allele of the ACE gene may be involved in the presence of carotid plaque but not in the extent of this plaque or asymptomatic lacunar stroke in Japanese subjects.

Association between angiotensin converting enzyme gene polymorphism and clinical features in autosomal dominant polycystic kidney disease

We investigated the association between angiotensin converting enzyme (ACE) gene polymorphism and clinical manifestations in 47 patients with autosomal dominant polycystic kidney disease (ADPKD). One-hundred, age- and sex-matched subjects with non-ADPKD served as the controls. ACE gene polymorphism was analysed using a GeneAnp kit. Renal size was determined by abdominal CT scan, by adding the longitudinal axis of each kidney. Incidence of extrarenal complication was also examined. Out of 47 patients, 24 patients (51%) were II, 18 (38%) ID and 5 (11%) DD type. The frequencies of the I and D alleles as well as the distributions of ACE genotypes in ADPKD did not differ from those in controls. The number of patients undertaking renal replacement therapy was 11 in II (46%), 6 (33%) in ID and 2 (40%) in DD genotype, respectively, that was not significantly different among the groups. The mean age of the initiation of renal replacement therapy did not vary among the three genotypes. The slopes of 1/serum creatinine did not differ between II and ID genotypes, whose initial serum creatinine levels ranged from 1.5 to 2.5 mg/dl. Renal size, blood pressure, and extrarenal complications including liver cysts and cardiac valvular disease were unrelated to the ACE genotypes. The present data suggested the irrelevance of ACE gene polymorphism in clinical manifestations in patients with ADPKD.