Angiotensin-converting enzyme gene polymorphism in systemic hypertension

Angiotensin-Converting Enzyme (ACE) gene polymorphism and arterial blood pressure among the Tawang Monpa of Eastern Himalayan Mountains: Is there a signature of natural selection?

OBJECTIVES

The present paper aims to characterize the Angiotensin-converting enzyme (ACE) genotype, with particular emphasis on its association with arterial oxygen saturation, arterial blood pressure, hemoglobin [Hb] concentration, and ventilatory measures among the Tawang Monpa, a high-altitude native population of the Eastern Himalaya, India.

METHODS

A cross-sectional sample of 168Monpa participants from Tawang town, Arunachal Pradesh, India, was selected who live at an altitude of ∼3,200 meters (m) above sea level. For each participant, height, weight, and skinfold thickness were measured, based on which body mass index (BMI, kg/m2) and percentage of body fat (%BF) were calculated. Physiological measures, such as the transcutaneous arterial oxygen saturation (SaO2), hemoglobin [Hb] concentration, forced vital capacity (FVC), forced expiratory volume in 1-second (FEV1), and systemic arterial blood pressure were measured. First, the peripheral venous blood samples (four ml) were drawn, and then white blood cells were separated for the ACE genotyping of each participant.

RESULTS

Unlike high-altitude natives from Peru and Ladakh, who exhibit high frequencies of II homozygotes, the Tawang Monpa shows a significantly high frequency of ID heterozygotes (p<0.0001). In addition, no significant association was identified between ACE gene polymorphism and arterial blood pressure, oxygen saturation at rest, vital capacity, or [Hb] concentration.

DISCUSSION

The results suggest that the association of the ACE gene with resting SaO2 is inconsistent across native populations living under hypobaric hypoxia. Further, ACE I/D gene polymorphism may not be under natural selection in specific native populations, including Tawang Monpa, for their adaptation to high-altitude hypoxia.

Association Between Polymorphism of the Angiotensin I Converting Enzyme Gene and Hypertension in Turkish Type II Diabetic Patients

It has been suggested that an insertion/deletion (I/D) polymorphism in intron 16 of the angiotensin converting enzyme (ACE) gene may be associated with essential hypertension. The aim of this study was to examine the association between ACE I/D polymorphism with blood pressure level and hypertension status in Turkish type 2 diabetic subjects. Hundred and seven hypertensive (78 female, 29 male) and 132 normotensive type 2 diabetic subjects (73 female, 59 male) and 138 sex and age matched control subjects (87 female, 51 male) without diabetes and hypertension were included into the study. The I/D polymorphism was determined by polymerase chain reaction (PCR). There were no statistically difference in genotypic and allelic frequencies of the ACE I/D polymorphism between the hypertensive and normotensive diabetic patients and control subjects. Also no significant differences was detected in systolic and diastolic blood pressure among three different genotypes. ACE I/D polymorphism does not seem to play an important role in the development of hypertension in Turkish type 2 diabetic subjects, but prospective studies may show an association between ACE gene polymorphism and the development of hypertension in diabetic subjects.

ACE Inhibitor-Induced Angioedema: a Review

PURPOSE OF REVIEW

This study aims to examine current knowledge on the occurrence, pathophysiology, and treatment of angioedema among patients who receive angiotensin-converting enzyme inhibitors.

RECENT FINDINGS

Angiotensin-converting enzyme inhibitors (ACE-I), a medication class used by an estimated 40 million people worldwide, are associated with angioedema that occurs with incidence ranging from 0.1 to 0.7%. The widespread use of ACE-I resulted in one third of all emergency department visits for angioedema. Angioedema occurs more frequently in African Americans, smokers, women, older individuals, and those with a history of drug rash, seasonal allergies, and use of immunosuppressive therapy. The pathophysiology of ACE-I-induced angioedema involves inhibition of bradykinin and substance P degradation by ACE (kininase II) leading to vasodilator and plasma extravasation. Treatment modalities include antihistamines, steroids, and epinephrine, as well as endotracheal intubation in cases of airway compromise. Patients with a history of ACE-I-induced angioedema should not be re-challenged with this class of agents, as there is a relatively high risk of recurrence.

CONCLUSION

ACE-I are frequently used therapeutic agents that are associated with angioedema. Their use should be avoided in high-risk individuals and early diagnosis, tracheal intubation in cases of airway compromise, and absolute avoidance of re-challenge are important.

Association between angiotensin-converting enzyme insertion/deletion genetic polymorphism and hypertension in a sample of Lebanese patients

BACKGROUND/AIM

several studies have looked at the potential link between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and the risk of hypertension and have shown that the DD polymorphism may be associated with a higher prevalence of hypertension. Our objective was to assess for possible association between ACE variants and hypertension in a sample of Lebanese patients.

METHODS

one hundred ninety-two Lebanese subjects were included. DNA was isolated and amplified by polymerase chain reaction. The products were identified by gel electrophoresis according to their size.

RESULTS

one hundred fifteen (59.9%) patients were hypertensive and 77 (40.1%) were nonhypertensive with the following genotype frequencies: 43.4% DD, 45.2% ID, and 11.4% II compared with 35.2% DD, 51.9% ID, and 12.9% II, respectively. Age was found to be the most significant risk factor for hypertension. This was more prominent when accounting for ACE genotype; for instance, the DD genotype with age had a significantly higher odds ratio (OR = 11.852; p = 0.001) than the ID genotype with age (OR = 4.599; p = 0.006), II genotype with age (OR = 1.866; p = 0.519), and age alone (OR = 5.558; p = 0.006).

CONCLUSION

our results show that the ACE I/D polymorphism is common in Lebanon, and the combinations of ACE D allele and age is associated with an increased risk of hypertension.

Effect of angiotensin-converting enzyme gene polymorphism on left ventricular remodeling after anteroseptal infarction

BACKGROUND AND HYPOTHESIS

Genetic influence on cardiac remodeling is uncertain. The purpose of this study is to determine the effects of polymorphism of the angiotensin-converting enzyme (ACE) gene on cardiac remodeling after myocardial infarction.

METHODS

The subjects were 43 patients with old anteroseptal myocardial infarction. Based on the polymorphism of the ACE gene, they were classified into a deletion group of 25 patients (D/D genotype in 4 and D/I genotype in 21) and an insertion group of 18 patients (all I/I genotype). Echocardiograms were used to determine left ventricular end-diastolic and end-systolic diameters, interventricular septal and posterior wall thicknesses, left ventricular mass, left atrial diameter, and left ventricular ejection fraction. Blood concentrations of atrial and brain natriuretic peptide were also measured.

RESULTS

Left ventricular end-systolic and end-diastolic dimensions, left ventricular mass, and levels of both atrial and brain natriuretic peptide were significantly higher in the deletion group. In contrast, septal thickness, posterior wall thickness, and ejection fraction showed no differences between the two groups.

CONCLUSIONS

In patients with old anteroseptal infarction, ACE gene polymorphism of the D/D and D/I genotypes has a stronger influence on left ventricular remodeling than polymorphism of the I/I genotype.

Influence of angiotensin-converting enzyme gene polymorphism on development of athlete's heart

BACKGROUND AND HYPOTHESIS

Genetic influence on development of athlete's heart is uncertain. This study investigated whether angiotensin-converting enzyme (ACE) gene polymorphism influenced development of athlete's heart.

METHODS

Forty-three participants in a 100-km ultramarathon were classified on the basis of ACE gene polymorphism into a deletion group (n = 26) and an insertion group (n = 17). Echocardiograms were recorded to determine left ventricular end-diastolic and end-systolic diameters, interventricular septal thickness, left ventricular posterior wall thickness, left ventricular mass, and ejection fraction.

RESULTS

Left ventricular end-diastolic diameter (65.5 +/- 4.0 mm) and left ventricular mass (369.5 +/- 73.9 g) were significantly larger in the subjects with deletion than in those with insertion (57.4 +/- 4.2 mm, 306.5 +/- 93.7 g). However, no significant differences in the other parameters were noted.

CONCLUSIONS

In long-distance runners, ACE gene polymorphism of the D/D and D/I genotypes has a stronger influence on left ventricular hypertrophy than polymorphism of the I/I genotype.

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

AIM

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

METHODS

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

RESULTS

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

INTERPRETATION

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

Single nucleotide polymorphism detection by polymerase chain reaction-restriction fragment length polymorphism

Accurate analysis of DNA sequence variation in not only humans and animals but also other organisms has played a significant role in expanding our knowledge about genetic variety and diversity in a number of different biological areas. The search for an understanding of the causes of genetic variants and mutations has resulted in the development of a simple laboratory technique, known as the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, for the detection of single nucleotide polymorphisms (SNPs). PCR-RFLP allows rapid detection of point mutations after the genomic sequences are amplified by PCR. The mutation is discriminated by digestion with specific restriction endonucleases and is identified by gel electrophoresis after staining with ethidium bromide (EtBr). This convenient and simple method is inexpensive and accurate for SNP genotyping and especially useful in small basic research studies of complex genetic diseases. The whole protocol takes only a day to carry out.

The gene polymorphism of the angiotensin I-converting enzyme correlates with tumor size and patient survival in colorectal cancer patients

We studied the putative significance of angiotensin I-converting enzyme (ACE) in colorectal cancer (CRC) biology. Local expression of ACE was investigated by quantitative reverse transcription-polymerase chain reaction and by immunohistochemistry in CRCs and adenomas. ACE insertion (I)/deletion (D) polymorphism was studied in 141 CRC patients and 189 controls. ACE mRNA was upregulated in CRCs compared to corresponding nonlesional tissues (2.5-fold; P = .009). ACE protein was more commonly expressed in adenomas [17 (81%)] and cancer epithelial cells [22 (100%)] than in corresponding non-neoplastic crypt and surface epithelium [2 (10%) and 2 (9%), respectively]. Thirty-seven CRC patients (26%) carried II genotype, 69 (49%) carried ID genotype, and 35 (25%) carried DD genotype. The distribution of the genotypes did not differ from that of controls. Female CRC patients more commonly carried the ID genotype and less frequently the II and DD genotypes compared with male patients (P = .033). Men heterozygous or homozygous for the D-allele had larger tumors compared to carriers of the II genotype (P < .01). Women homozygous for the D-allele lived longer than carriers of the ID and II genotypes. Our study shows that ACE is differentially expressed in CRCs and that gene polymorphism is associated with gender-specific differences in primary tumor size and patient survival.

Angiotensin I-converting enzyme insertion-related genotypes and allele are associated with higher susceptibility of endometriosis and leiomyoma

Endometriosis and leiomyoma display features similar to malignancy, requiring neovascularization to proliferation and growth. Altered vascular-related genes might be related to the development of endometriosis and leiomyoma. Polymorphisms of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) genes have been linked with some vascular diseases. This study investigates whether ACE I/D gene polymorphisms could be used as markers of susceptibility in endometriosis and leiomyoma. Women were divided into three groups: (1) endometriosis (n = 125); (2) leiomyoma (n = 120); (3) normal controls (n = 128). Genomic DNA was obtained from peripheral leukocyte. ACE I/D gene polymorphisms in intron 16 were amplified by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) Genotypes and allelic frequencies in both groups were compared. We observed the genotype distribution and allele frequency of ACE I/D gene polymorphisms in both groups were significantly different. Proportions of ACE*I homozygote/heterozygote/D homozygote in both groups were: (1) 50.4/24/25.6%; (2) 25/23.33/51.67%; (3) 10.2/29.7/60.1%. Proportions of I/D alleles in each group were: (1) 62.4/37.6%; (2) 36.7/63.3%; (3) 25/75%. We concluded that ACE*I/D gene polymorphisms are associated with endometriosis and leiomyoma susceptibilities. ACE*I-related genotypes and allele are strongly related to the occurrence of endometriosis and moderately related to the occurrence of leiomyoma.

Association between the insertion/deletion polymorphism of the angiotensin I-converting enzyme gene and risk for psoriasis in a Chinese population in Taiwan

BACKGROUND

Genetic factors play an important role in susceptibility for psoriasis. The angiotensin I-converting enzyme (ACE) is expressed by keratinocytes. Administration of ACE inhibitors may induce or exacerbate psoriasis in clinical practice. Thus, ACE gene variants may contribute to the genetic background of psoriasis.

OBJECTIVES

To assess the role of the ACE insertion/deletion (I/D) polymorphism in psoriasis among ethnically Chinese Taiwanese subjects.

METHODS

In total, 312 patients with psoriasis and 615 control subjects were analysed for the ACE I/D polymorphism by polymerase chain reaction.

RESULTS

A marginally significant difference (P=0 x 035) was found in the distribution of ACE I/D genotype frequencies between patients with psoriasis and controls. The frequency of the II genotype in patients with psoriasis was significantly higher than that in the control group (55 x 1% vs. 46 x 7%, respectively, P=0 x 015). Although the I allele frequency in patients with psoriasis (72 x 4%) was higher than that in the control group (68 x 2%), the difference was not significantly different (P=0 x 062). After adjusting for age and gender, carriers of the II genotype were 1 x 45 (95% confidence interval 1 x 09-1 x 92) times more likely than noncarriers to have psoriasis (P=0 x 010).

CONCLUSIONS

Our results suggest that the presence of the I allele may confer susceptibility to development of psoriasis among ethnically Chinese Taiwanese individuals.

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.

The angiotensin I-converting enzyme gene insertion/deletion polymorphism is linked to early gastric cancer

The insertion/deletion polymorphism of the angiotensin I-converting enzyme (ACE) gene has recently been linked to the pathogenesis and progression of human cancers. Using genomic DNA from 88 patients with early gastric cancer confined either to mucosa (pT(1a)) or submucosa (pT(1b)), we assessed the insertion (I) and deletion (D) polymorphism by PCR analysis and compared it with a large noncancer control population (n = 145). In the noncancer control group, the II genotype was observed in 33 (23%) individuals, whereas the ID and DD genotypes were found in 72 (50%) and 40 (27%) individuals, respectively. Interestingly, in the cancer group, we found the II genotype in six (7%) patients and the ID genotype in 46 (52%) individuals, whereas the DD genotype was observed in 36 (41%) individuals (P = 0.0034). Accordingly, the odds ratio for the II genotype was 0.20 [95% confidence interval (95% CI), 0.08-0.54; P = 0.009] and 0.55 for the ID/II genotype (95% CI, 0.31-0.96; P = 0.044) using the high-activity genotype DD as the reference category. No correlation was found among tumor type, tumor stage, the presence of Helicobacter pylori, and the ACE genotype. Our study provides further evidence that the ACE insertion/deletion gene polymorphism may be linked to the development of early gastric cancer.

Weight Gain after Liver Transplantation and the Insertion/Deletion Polymorphism of the Angiotensin-Converting Enzyme Gene

BACKGROUND

Subjects who carry the D allele of the angiotensin-converting enzyme (ACE) gene have higher plasma and tissue angiotensin II levels, possibly concurrent with the development of obesity. In transplant recipients, treatment with calcineurin antagonists would magnify these effects. The present study verifies whether the allelic variants of ACE are a factor involved in excess weight gain after liver transplantation.

METHODS

A consecutive series of 108 liver transplant recipients (73 males) were studied. Recipient ACE genotypes, determined by a polymerase chain reaction-based method, were related to body mass changes 1 year after transplant.

RESULTS

Body mass index (BMI) increased from the pretransplant value of 25.1+/-3.3 kg/m2 to 25.9+/-3.5 kg/m2 (P<0.005). The difference was mainly attributable to recipients carrying 1 D allele or more (N=88) in whom the BMI increased from 25.3+/-3.1 kg/m2 to 26.3+/-3.3 kg/m2 (P<0.005). A BMI of 25 kg/m or greater was measured in 30 of 45 deletion/deletion homozygotes and 25 of 43 insertion/deletion heterozygotes; in contrast, 14 of 20 insertion/insertion homozygotes had a normal body mass (P<0.01). Among patients with normal body mass pretransplant (N=56), none of 13 insertion/insertion homozygotes reached a BMI value 25 kg/m or greater posttransplant (P<0.005). At multivariate analysis, pretransplant body mass and carriage of 1 D allele or more were independent predictors of body mass gain greater than 2 kg/m.

CONCLUSIONS

Carriage of the D allele of the ACE gene is a strong, independent risk factor for excess weight gain after liver transplantation.

Genetic determinants of nonmodulating hypertension

We sought to determine whether genes of the renin-angiotensin-aldosterone system can predict the nonmodulating intermediate phenotype in essential hypertension. Aldosterone responses to angiotensin II were assessed in 298 subjects with hypertension. Subjects were genotyped at the angiotensinogen M235T, angiotensin-converting enzyme I/D, aldosterone synthase C-344 T, renin, angiotensin II type 1 receptor, and adducin loci. The data were analyzed by Student t test, ANOVA, stepwise linear regression and general linear model or GENMOD regression techniques, and chi2 analysis odds ratios (ORs). Aldosterone response varied by genotype for angiotensin and aldosterone synthase but not for the other loci. The combination of angiotensinogen 235 TT and angiotensin-converting enzyme DD showed further reduction (P=0.0377) when compared with angiotensinogen 235 TT alone, an example of genetic epistasis. When the subject was required also to possess the CYP11B2 -344 TT genotype, there was a further substantial reduction. Of these 3 loci, only angiotensinogen 235 TT significantly increased the OR of predicting the nonmodulating hypertensive phenotype (OR, 2.00; 95% confidence interval, 1.152 to 3.51). However, when angiotensin-converting enzyme DD was combined with angiotensinogen 235 TT, the OR nearly doubled to 3.74, with a further increase to 5.36-fold when the subject possessed all 3 genotypes. Thus, the angiotensinogen, angiotensin-converting enzyme, and aldosterone synthase genotypes identified individuals with the nonmodulating phenotype with an increasing degree of fidelity. For this subclass of essential hypertension, it is likely that genotyping can be substituted for complex phenotyping for therapeutic and preventive decision making.

Angiotensin converting enzyme gene polymorphism and traditional Sasang classification in Koreans with cerebral infarction

Sasang constitutional medicine is a major branch of Korean traditional oriental medicine. Constitutions of Sasang medicine refer to Taeyangin, Taeumin, Soyangin, and Soumin. The differences of disease severity to be shown in the constitution may be due to genetic factors. Therefore, we examined interrelationship among cerebral infarction, CI, angiotensin converting enzyme (ACE) gene polymorphism, and Sasang constitutional classification. We investigated the association between ACE genotype and CI by case-control study in a Korean population. We also classified CI patients and control group into groups according to Sasang constitutional medicine. 208 CI patients and 643 controls without CI were examined. ACE genotype was determined by 7.5 % polyacrylamide gel separation after DNA amplification. The ACE/DD genotype was not associated with CI. The frequency of Taeumin of Sasang constitutional medicine in patients with CI was significantly higher than that in controls (chi2=41.202, p<0.001). However, the Taeumin constitution did not enhance the relative risk for CI in the subjects with ACE/DD genotype. Although we did not find any association between ACE gene polymorphism and CI in Koreans, there were significant differences in allele frequencies between Koreans and Europeans, but not Japanese and Chinese populations. Furthermore, we first attempted to evaluate the efficacy of Sasang constitutional medicine, and to find an association with CI.

Association of angiotensin-converting enzyme DD genotype with blood pressure sensitivity to weight loss

BACKGROUND

Weight loss and sodium reduction are useful nonpharmacologic interventions in the management of hypertension. Salt sensitivity--the degree of blood pressure change in response to a change in sodium load--has been extensively explored. However, the determinants of the extent of blood pressure change after weight reduction have not been evaluated.

METHODS

We studied the relationship of the angiotensin-converting enzyme insertion-deletion (ACE I/D) polymorphism to blood pressure change after weight loss in the Trial Of Nonpharmacologic interventions in the Elderly (TONE). We focused on the 86 overweight white hypertensive TONE participants who were randomized to weight loss only.

RESULTS

A similar weight reduction was observed across all ACE genotypes, whereas a significantly greater decrease in blood pressure after weight loss was seen among participants with the DD genotype. In addition, DD participants had a higher probability of remaining normotensive for the duration of the trial.

CONCLUSIONS

The DD genotype may be associated with higher "weight sensitivity" in overweight white hypertensive persons, potentially through reduced activity of the renin-angiotensin and sympathetic systems after weight loss.

Role of the alpha-adducin genotype on renal disease progression

BACKGROUND

A genetic susceptibility to hypertension may predispose to the development of end-stage renal disease (ESRD) and promote a more rapid loss of renal function in patients with renal diseases. The alpha-adducin (ADD) gene, alone or in combination with the angiotensinogen (AGT) and the angiotensin-converting enzyme (ACE), is a candidate for abnormal blood pressure regulation and thus for increased susceptibility or faster progression to ESRD.

METHODS

Genotyping for the G460W-ADD, M235T-AGT and the insertion/deletion (I/D)-ACE gene polymorphisms was performed in 260 control subjects and 260 ESRD patients using polymerase chain reaction, gel analysis and appropriate restriction digest.

RESULTS

The frequencies of the ADD, AGT and ACE genotypes in ESRD patients did not differ from observed frequencies in control subjects. The average (+/-SE) time from diagnosis to the onset of ESRD tended to be shorter in the presence of the ADD-460WW (5.1 +/- 1.1 years, N = 10) than with the GW (9.9 +/- 0.7 years, N = 81) and GG (11.3 +/- 1.0 years, N = 164) genotypes (F-ratio=2.71, P = 0.068; WW vs. GW P < 0.06 and vs. GG <0.03). In the 167 patients homozygous for the ADD-G allele, a more rapid progression with the ACE-DD genotype as compared to ACE-DI and II was found (P < 0.02).

CONCLUSIONS

The ADD genotype is predictive of the course of renal function loss in an unselected renal population and influences the effect of the ACE genotype to modulate the rate of progression to ESRD. Thus, the ADD genotype may play a role for the understanding of interindividual differences in the course of renal diseases.

Recipient RAS gene variants and renal allograft function

BACKGROUND

Genetic variants of the renin-angiotensin system (RAS) have been implicated in the progression of native kidney diseases. A decreased long-term renal allograft function has also been associated with increased activity of RAS, which may be genetically determined.

METHODS

The effect of the angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin type 1 receptor (AGT1R), and aldosterone synthase (CYP11B2) genotypes on renal function was investigated in 223 first-allograft recipients. Graft function was estimated by yearly determinations of serum creatinine. Genotyping was performed for the M235T-AGT, the I/D-ACE, the A1166C-AGT1R, and the -344T/C-CYP11B2 gene polymorphisms using polymerase chain reaction.

RESULTS

The percentage of patients with preserved stable graft function up to 15 years after transplantation was higher when mean blood pressure was <97 mmHg, than when it was >117 mmHg (60 vs. 25% of patients). The CYP11B2 genotype predicted long-term stable graft function with more patients suffering from worsening renal function with the CYP11B2 TT than the CC genotype (P=0.002). There was a weak association between the AGT1R genotype (P=0.037), but not the AGT or ACE genotypes, and a preserved long-term graft function. Cox proportional hazards estimation showed no interactions between the observed effect of CYP11B2 genotype on renal function over time and the number of HLA class I and II matches, other RAS genotypes, graft function, or mean blood pressure at 1 year after transplantation.

CONCLUSIONS

The rate of decline in renal allograft function is strongly associated with the CYP11B2 but not AGT, ACE, or AGT1R genotypes. This finding suggests that certain genetic factors related to the RAS are important determinants of long-term renal allograft function.

Angiotensin-converting enzyme degrades Alzheimer amyloid beta-peptide (A beta ); retards A beta aggregation, deposition, fibril formation; and inhibits cytotoxicity

We have demonstrated that the angiotensin-converting enzyme (ACE) genotype is associated with Alzheimer's disease (AD) in the Japanese population (). To determine why ACE affects susceptibility to AD, we examined the effect of purified ACE on aggregation of the amyloid beta-peptide (A beta) in vitro. Surprisingly, ACE was found to significantly inhibit A beta aggregation in a dose response manner. The inhibition of aggregation was specifically blocked by preincubation of ACE with an ACE inhibitor, lisinopril. ACE was confirmed to retard A beta fibril formation with electron microscopy. ACE inhibited A beta deposits on a synthaloid plate, which was used to monitor A beta deposition on autopsied brain tissue. ACE also significantly inhibited A beta cytotoxicity on PC12 h. The most striking fact was that ACE degraded A beta by cleaving A beta-(1-40) at the site Asp(7)-Ser(8). This was proven with reverse-phase HPLC, amino acid sequence analysis, and MALDI-TOF/MS. Compared with A beta-(1-40), aggregation and cytotoxic effects of the degradation products A beta-(1-7) and A beta-(8-40) peptides were reduced or virtually absent. These findings led to the hypothesis that ACE may affect susceptibility to AD by degrading A beta and preventing the accumulation of amyloid plaques in vivo.

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

BACKGROUND

Hypertension contributes to the progression to renal failure. A genetic susceptibility to hypertension may predispose to the development of end-stage renal disease (ESRD) and promote a more rapid progression to ESRD in patients with renal diseases. Genes encoding for angiotensinogen (AGT), angiotensin-converting enzyme (ACE), and aldosterone synthase (CYP11B2) are candidates for abnormal blood pressure regulation.

METHODS

Genotyping was performed in 327 control subjects and 260 ESRD patients for the M235T-AGT, the insertion/deletion (I/D)-ACE, and the -344T/C-CYP11B2 gene polymorphisms using polymerase chain reaction, gel analysis, and appropriate restriction digest when required.

RESULTS

Genotype frequencies did not differ significantly between ESRD patients and controls. When ESRD diabetic subjects were compared with diabetic patients without nephropathy, the prevalence of the AGT-MM genotype was lower (28.1 vs. 52.8%, P < 0.01), while the AGT-TT genotype was higher (15.6 vs. 2.7%, P < 0.05). The AGT-TT genotype was associated with a faster progression to ESRD in patients with glomerulonephritis (P < 0.05). In the total ESRD population, progression of renal disease was faster with the ACE-DD than with the DI and II alleles (P < 0.05). This association was particularly strong when the interaction with the AGT genotype was analyzed, with a rapid progression in ACE-DD as compared with ACE-DI and II in patients with the AGT-MM genotype (P < 0.01).

CONCLUSIONS

Susceptibility for ESRD and faster progression to ESRD are linked with the AGT genotype in diabetic patients. Faster progression to ESRD is associated with the ACE genotype when the total population with ESRD and with the AGT genotype when patients with glomerulonephritis are considered. Thus, genes of the renin-angiotensin-aldosterone system are candidate genes for further understanding of the interindividual differences in the development and course of ESRD.

Angiotensin-converting enzyme gene I/D polymorphism in malignant hypertension

BACKGROUND

The mechanism of the rapid transition of a stable benign hypertensive disease to a severe and devastating malignant hypertension is not fully understood. However, the renin angiotensin system, which is highly activated in malignant hypertension, is established as an important pathogenetic factor in different cardiovascular and renal diseases. Over the last decade, a polymorphism in genes regulating this system has been found. This includes the 287 bp sequence deletion (D)/insertion (I) polymorphism in the angiotensin-converting enzyme (ACE) gene and the methionine (M) to threonine (T) point mutation polymorphism in the angiotensinogen (AGT) gene. These gene polymorphisms have been associated with various cardiovascular and renal diseases and the aim of this study was to investigate whether they were linked to malignant hypertension.

METHODS

Forty-two patients with malignant hypertension (mean age 55 years), 42 patients with non-malignant hypertension (mean age 57 years) and 85 normotensive control subjects (mean age 42 years) were investigated with respect to ACE I/D and AGT M/T genotypes. DNA was prepared by standard methods from isolated white blood cells and analysed by the PCR technique. The PCR reaction used in the detection of the ACE I/D polymorphism was optimized for an equal amplification of the I and D alleles.

RESULTS

The frequency of the DD genotype was significantly increased in patients with malignant hypertension (43%) compared with patients with non-malignant hypertension (14%) and normotensive control subjects (18%) (p <0.01) for both. The frequency distribution of AGT M/T genotype did not differ between patients with malignant and non-malignant hypertension.

CONCLUSION

The DD genotype of the ACE gene occurred more than twice as often in malignant hypertension than in non-malignant hypertension and indicates that ACE gene polymorphism is a significant risk factor for initiation of malignant hypertension.

Angiotensin-converting enzyme genotype is associated with Alzheimer disease in the Japanese population

We compared the distribution of an insertion (I)/deletion (D) polymorphism of the gene coding for the angiotensin-converting enzyme (ACE) in 133 Japanese sporadic Alzheimer disease (AD) patients with 257 controls. The association between AD and ACE genotypes or alleles was found to be significant. The frequency of II genotypes was 1.4 times higher in AD than controls, while that of DD genotypes was only 0.4 times as high. The altered distribution of ACE alleles in patients with AD appeared to be independent of apolipoprotein E.

Polymorphism in the angiotensin converting enzyme but not in the angiotensinogen gene is associated with hypertension and type 2 diabetes: the Skaraborg Hypertension and diabetes project

OBJECTIVE

To study the association between polymorphisms in the angiotensin converting enzyme (ACE) gene and angiotensinogen (AGT) gene and hypertension and/or type 2 diabetes in a community population.

PATIENTS AND METHODS

The insertion (I)/deletion (D) polymorphism of the ACE gene and the M235T polymorphism of the AGT gene were genotyped in 773 nondiabetic individuals with hypertension, 193 normotensive patients with type 2 diabetes, 243 patients with type 2 diabetes and hypertension, and in 820 normotensive control individuals identified in a community-based study.

RESULTS

The DD genotype was associated with hypertension in individuals less than 70 years [odds ratio (OR) = 1.54, confidence interval (CI) = 1.09-2.18] and remained so when patients with type 2 diabetes were excluded from the analysis (OR = 1.45, CI = 1.01-2.09). The strongest association was with the combination of type 2 diabetes and hypertension (OR = 2.19, CI = 1.09-4.38). There was no association with type 2 diabetes without hypertension. No association was observed between the M235T variant or the 3'-microsatellite polymorphism of the AGT gene and hypertension.

CONCLUSION

The D-allele of the ACE gene ID polymorphism increases susceptibility to hypertension, particularly when associated with type 2 diabetes. No association was observed between the M235T variant or 3'-microsatellite polymorphism of the AGT gene and hypertension.