Angiotensin converting enzyme gene polymorphism and activity in Turkish patients with essential hypertension

Studies in various ethnic groups have shown contradictory evidence on the association of the angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism with essential hypertension. We conducted a case-control study in Samsun, Turkey, to examine the association between ACE genotype, ACE serum activity, and blood pressure. Serum ACE activity was measured and ACE I/D polymorphism performed in 165 hypertensive and 143 normotensive subjects. Genomic DNA was extracted from blood samples and amplified by polymerase chain reaction (PCR). PCR primers were flanking the polymorphic region in intron 16 of the ACE gene. The distribution of the DD, ID, and II ACE genotypes was 65, 77, and 23 in hypertensive patients and 42, 82, and 19 in normotensive subjects (P > .05). The estimated frequency of the insertion allele was 0.37 in hypertensive and 0.42 in normotensive subjects. Nevertheless, sensitivity analysis, based on positive family history and severity of hypertension, suggested that significant associations existed between more homogeneous groups of hypertensives and normotensives (P < .05). ACE genotype influenced ACE activity and the highest level was in DD genotype, being the lowest in II genotype. ACE serum levels were significantly higher in hypertensives as compared with normotensives (P < .01). A modest correlation was observed between blood pressure and ACE among hypertensive persons (r = 0.25, P < .05) and this did persist in multivariate analysis (P < .05 for systolic blood pressure and P < .005 for diastolic blood pressure). These data suggest that ACE DD genotype may have predisposing effects on severe hypertensives and cases with positive family history, and that ACE may be one of the independent factors on hypertension.     

Neutral endopeptidase and angiotensin I converting enzyme insertion/deletion gene polymorphism in humans

Neutral endopeptidase (NEP) hydrolyses angiotensins (Ang) I and II and generates angiotensin-(1-7) [Ang-(1-7)]. In humans, the insertion/deletion (I/D) angiotensin-I converting enzyme (ACE) gene polymorphism determined plasma ACE levels by 40%. In rats, a similar polymorphism determines ACE levels which are inversely associated to NEP activity. The objective of this study is to evaluate the relationship between ACE expression and plasma NEP activity in normotensive subjects and in hypertensive patients. In total, 58 consecutive patients with hypertension, evaluated in our Hypertension Clinic, were compared according to their ACE I/D genotypes with 54 control subjects in terms of both plasma ACE activity and NEP activities. Plasma ACE activity was elevated 51 and 70% in both DD ACE groups (normotensives and hypertensives) compared with their respective ID and II ACE groups (P<0.001). A significant effect of the ACE polymorphism and of the hypertensive status on ACE activity was observed (P<0.001). In normotensive DD ACE subjects, NEP activity was 0.30+/-0.02 U/ml, whereas in the normotensive II ACE and in the normotensive ID ACE subjects NEP activity was increased 65 and 48%, respectively (P<0.001). In the hypertensive DD ACE patients, NEP activity was 0.47+/-0.03 U/mg. An effect of the I/D ACE genotypes on NEP activity (P<0.04) and an interaction effect between the I/D ACE genotype and the hypertensive status were also observed (P<0.001). These results are consistent with a normal and inverse relationship between the ACE polymorphism and NEP activity in normotensive humans (as is also observed in rats). This normal relationship is not observed in hypertensive patients.     

Angiotensin I Converting Enzyme Gene Polymorphism in Chinese Patients With Hypertension

Reports from different ethnic populations failed to show consistent findings on the association of hypertension with insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme (ACE) gene. In this population association study in Chinese, we compared the distribution of the ACE genotypes and allele frequency in 150 healthy controls with normal blood pressure and 148 hypertensive patients categorized by age. Although the frequencies of homozygote deletion (DD) genotype and deletion allele were greater in Chinese with hypertension than in normotensive controls (0.23 vs 0.13 and 0.44 v 0.37, respectively), the differences were not significant by χ² analysis (P = .07 and .09, respectively). Furthermore, we did not find the trend of decreasing number of DD genotype in older hypertensive Chinese patients. The results indicated a much lower prevalence of ACE/DD genotype in Chinese than in Caucasians and a modest association between I/D polymorphism of the ACE gene and hypertension in Chinese.     

Distribution of different HLA antigens in Greek hypertensives according to the angiotensin-converting enzyme genotype

The angiotensin-converting enzyme (ACE) insertion/deletion polymorphism is an independent risk factor for cardiovascular disease. It has also been suggested that some HLA genes may contribute to the genetic susceptibility to essential hypertension. So far, an association between ACE polymorphism and HLA antigens in arterial hypertension has not been reported. We have studied 94 subjects with newly diagnosed essential hypertension, 49 men and 45 women (mean age, 52.3 ± 11.3 years), as well as 104 randomly selected, age- and gender-matched normotensive individuals (54 men and 50 women, mean age 48.7 ± 10.8 years). Both cohorts originated from the Greek population and lived in the greater Athens area. The ACE genotype was analyzed by polymerase chain reaction. HLA class I and II antigens were studied by serologic and molecular techniques.The prevalence of the ACE genotypes did not differ significantly between hypertensives and normal individuals. The casual blood pressure levels and the average ambulatory blood pressure levels were similar among the three ACE genotypes. Hypertensives with the ACE-DD genotype were characterized by an increased prevalence of the HLA-A2 antigen (50% v 31.4%, P < .005) and DR6 (16.7% v 11.4%, P < .01) in comparison to the normotensive subjects with the ACE-DD genotype. HLA-A24 was found more frequently among the hypertensives with the ACE-ID genotype than in the normal controls with the same genotype (35.5% v 26.4%, P < .05). ACE-DD genotype is associated with a high prevalence of specific HLA antigens. The coexistence of the ACE-DD genotype with certain HLA phenotypes could reveal a distinct hypertensive population with increased risk for cardiovascular events.     

高血压患者血管紧张素Ⅱ受体基因多态性与颈动脉硬化间的关系

为探讨血管紧张素Ⅱ１型受体基因多态性与原发性高血压及高血压颈动脉硬化之间的关系,将高血压患者（ｎ＝１２０）和正常对照者（ｎ＝８６）进行血压、身高、体重、空腹血糖及血清总胆固醇和甘油三酯浓度测定,用饱和盐析法常规提取外周血白细胞ＤＮＡ,采用多糖酶链反应结合限制性内切酶法检测血管紧张素Ⅱ１型受体基因的Ｃ１１６６等位基因在正常人和原发性高血压患者中的频率。并测定正常对照组（ｎ＝３２）和高血压组（ｎ＝６８     

高血压患者血管紧张素Ⅱ受体基因多态性与颈动脉硬化间的关系

为探讨血管紧张素Ⅱ 1型受体基因多态性与原发性高血压及与高血压颈动脉硬化之间的关系 ,将高血压患者 (n =12 0 )和正常对照者 (n =86 )进行血压、身高、体重、空腹血糖及血清总胆固醇和甘油三酯浓度测定 ,用饱和盐析法常规提取外周血白细胞DNA ,采用多聚酶链式反应结合限制性内切酶法检测血管紧张素Ⅱ 1型受体基因的C116 6等位基因在正常人和原发性高血压患者中的频率。并测定正常对照组 (n =32 )和高血压组 (n =6 8)颈总动脉内膜 -中膜厚度、管腔内径及壁 腔比值。结果发现 ,高血压患者血管紧张素Ⅱ 1型受体基因AC基因型频率比正常对照者高 (P <0 .0 1) ;高血压组C116 6等位基因频率高于正常对照组 (P <0 .0 5 ) ;AC基因型高血压患者颈总动脉内膜 -中膜厚度比AA基因型高血压患者厚 (P <0 .0 5 ) ,AC基因型高血压患者壁 腔比值大于AA基因型高血压患者 (P <0 .0 1) ,AA和AC基因型高血压患者颈总动脉内径无差别。提示血管紧张素Ⅱ 1型受体基因A116 6C多态性与中国人高血压病有关 ,并且可能与高血压动脉硬化有关     

血管紧张素转换酶基因插入/缺失多态性检测方法的研究

目的 采用三条引物法进行力紧张素转换酶（ACE）基因分型检测,并与Rigat法进行比较,以探讨Rigat造成DD型分型的错判率,并用此方法检测了中国汉族人群中ACE基因I／D基因型的分布频率以及插入（I）／缺失（D）多态性与高血压病（EH）间的相关性。方法 EH患（EH组）206例,用上述两种方法进行ACE基因分型;正常血压组（NT组）156例以及核心家系25个共118例,三条引物法进行ACE基因分型。结果 EH组Rigat法得出的DD型比例较三条引物法高。与三条引物法相比较,Rigat法对DD型的错判率为13．04％。用三条引物法进行基因分型的结果如下：（1）在NT组,ACE各基因型的分布频率为Ⅱ型0．51,ID型0．41,DD型0．08。等位基因频率为：I0．71,D0．29。（2）25个EH家系所有成员的基因分型结果,完全符合孟德尔遗传规律。（3）EH与NT两组间基因型和等位基因频率无显性差异。结论 三条引物法1次完成ACE基因分型,有良好的特异性、准确性和重复性。     

Exclusion of the ACE D/I gene polymorphism as a determinant of endothelial dysfunction

A deletion/insertion (D/I) polymorphism within the ACE gene may increase the risk of cardiovascular events through still unknown mechanisms. The latter may involve increased angiotensin II-induced NO breakdown and/or reduced agonist-mediated NO release. We therefore investigated whether the D allele of the ACE gene affects endothelium-dependent vasodilatation in mild-to-moderate primary hypertensive patients and healthy normotensive subjects. We compared in a cross-sectional study the forearm blood flow response of the 3 D/I genotypes with 5 incrementally increasing doses of the endothelium-dependent vasodilator acetylcholine (0.15, 0.45, 1.5, 4.5, and 15 microg. 100 mL(-1). min(-1)) in 142 subjects: 103 mild-to-moderate uncomplicated primary hypertensives (49.3+/-9.1 years old, 152+/-11/99+/-5 mm Hg) and 39 normotensives (44.6+/-15.3 years old, 122+/-12/78+/-6 mm Hg). We also assessed the endothelium-independent vasodilatation in the forearm, as blood flow response to 3 incrementally increasing doses of sodium nitroprusside (1, 2, and 4 microg. 100 mL(-1). min(-1)). The overall genotype distribution was II, n=10; ID, n=70; and DD, n=62. It did not differ significantly between primary hypertensives and normotensives. A significant blunting of endothelium-dependent vasodilatation in primary hypertensive patients compared with normotensive subjects (P:<0.001) was found. No effect of the DI genotype on endothelium-dependent and -independent vasodilatation was detected. Thus, these results obtained in a relatively large population do not support the contention that the D allele is associated with a blunting of either stimulated endothelial NO or donated NO responses in both mild-to-moderate primary hypertensive patients and normotensive subjects.     

M235T polymorphism of human angiotensinogen gene in essential hypertension in Polish population

Genetic factors play very important role in the pathogenesis of essential hypertension. Angiotensinogen gene is one of the candidate genes in the research concerning genetic background of elevated blood pressure. The aim of this work was to assess an association of M235T polymorphism in human angiotensinogen gene with essential hypertension in Polish population. 250 patients with essential hypertension and 150 normotensives were involved in the study. M235T polymorphism was detected using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods. Polymorphic allele and genotypes frequencies did not differ between hypertensive and normotensive groups. However T allele and TT genotype frequency among hypertensive men was higher than in normotensive men. The difference is statistically significant. T allele and TT genotype occurred more frequently in hypertensives with positive family history of essential hypertension. The difference between hypertensive men with positive family history and normotensive men was even more significant. This results are similar to those already published by other authors concerning Caucasian populations and indicate that angiotensinogen gene is involved in the determination of at least some cases of essential hypertension.     

The C242T CYBA polymorphism of NADPH oxidase is associated with essential hypertension

OBJECTIVE: Oxidative stress is implicated in hypertension. The reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases are the main source of superoxide in phagocytic and vascular cells. The C242T polymorphism of CYBA, the human gene that encodes p22phox, has been found to be functionally associated with vascular NADPH oxidase activity in atherosclerotic patients. We investigated the association of the C242T polymorphism with hypertension and its potential impact on NADPH oxidase activity. We also analysed the interaction of C242T polymorphism with the -930A/G CYBA variant. DESIGN: Case-control study in a random sample of 623 subjects (326 hypertensive patients and 297 normotensive controls) from the general population. METHODS: CYBA polymorphisms were determined by restriction fragment length polymorphism (RFLP) or allelic discrimination. NADPH oxidase activity and p22phox expression were quantified in phagocytic cells by chemiluminescence and by northern and western blots, respectively. RESULTS: The prevalence of the CC genotype and the C allele frequency were significantly higher (P < 0.05) in hypertensives than in normotensives. CC genotype remained associated with hypertension after adjusting for potential confounders in a logistic regression analysis. Increased phagocytic NADPH oxidase activity was observed in CC hypertensives compared with CT and TT hypertensives (P < 0.05). Enhanced plasma levels of von Willebrand factor were found in CC hypertensives compared with TT hypertensives (P < 0.05). The C242T polymorphism was not in linkage disequilibrium with the -930A/G CYBA promoter variation, which also associates with hypertension. CONCLUSION: The C242T CYBA polymorphism is associated with essential hypertension. Furthermore, hypertensives carrying the CC genotype of this polymorphism exhibit features of NADPH oxidase-mediated oxidative stress and endothelial damage.     

A1166C polymorphism of the angiotensin II type 1 receptor gene and essential hypertension in Han, Tibetan and Yi populations.

Our aim was to clarify whether substitution of cytosine for adenine at position 1166 (A1166C) polymorphism of the angiotensin II type 1 receptor (AT1R) gene is associated with susceptibility to essential hypertension in Han, Tibetan and Yi populations in China. This study involved 302 normotensive and 446 hypertensive subjects. The polymorphism was detected by polymelase chain reaction of genomic DNA and restriction fragment length polymorphism (PCR-RFLP) in genomic DNA. The data were analyzed by analysis of covariance (ANCOVA), X2 test, and multiple logistic regression. In normotensive controls, the A1166 allele frequencies were 0.979, 0.939 and 0.965 in Han, Tibetan and Yi participants, respectively. There was no significant intergroup variation in frequency of the allele in normotensives (X2=4.166, p=0.125). The frequency of the A1166 allele was significantly higher in Tibetan male hypertensives than that in normotensives (X2=11.46, p=0.001). There was no significant difference in A1166C genotype distribution and allele frequency between normotensives and hypertensives either in the Han (p=0.465) or Yi (p=0.357) populations. Body mass index in the Han and Yi populations (p=0.0001), age in the Tibetan and Yi populations (p=0.0001), and AA genotype in the Tibetan male population (p=0.0034) all were independent risk factors for hypertension. Diastolic blood pressure levels were significantly higher in Tibetan male subjects with the AA genotype than in those with the AC+CC genotype (p=0.0040). We concluded that the A1166 allele is very common in Han, Tibetan and Yi populations, approximately 1.35-fold more common than in Caucasians. The A1166 allele of the AT1R gene may be a predisposing factor for essential hypertension in Tibetan males. A1166C polymorphism of the AT1R gene is probably not involved in the pathogenesis of essential hypertension in Han or Yi populations.     

Abnormal Leucocyte Sodium Transport in Chinese Patients with Essential Hypertension and their Normotensive Offsprings

We studied changes in intracellular electrolytes and the rate constant of ²²Na efflux from isolated leucocytes in Chinese patients with essential hypertension and their normotensive offsprings. The hypertensives had an increase of sodium content and a reduction of the total or ouabain-sentive ²²Na efflux from leucocytes. The normotensives born of hypertensive parents showed lower sodium content, higher potassium content and reduced rate constant of oua-bain-insensitive ²²Na efflux from leucocytes. The results suggest that the inhibition of cell sodium pump activity may be a marker of essential hypertension. Abnormal cell sodium transport observed in normotensives with family history of hypertension may have some etiological linking with the inheritance of hypertension.     

中国汉族人血管紧张素转换酶基因I/D多态性与原发性高血压的关系

目的探讨ＡＣＥ基因Ｉ／Ｄ多态性在中国汉族人群分布规律及与原发性高血压（ＥＨ）的关系。方法取汉族ＥＨ病人１２１例，对照组９５人外周血，提取ＤＮＡ，应用ＰＣＲ技术进行ＡＣＥ基因Ｉ／Ｄ分型。结果在汉族血压正常群体中，ＡＣＥ基因Ｉ／Ｄ多态ＤＤ、ＤＩ、Ｉ基因型频率分别为２２％，４８％和３０％，其Ｄ和Ｉ等位基因频率分别为４６％和５４％。Ｉ／Ｄ多态分布符合Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ定律，达到遗传平衡，具有群体代表性。ＥＨ组与正常组相比，基因型和等位基因分布均具有显著统计学差异（Ｐ＜０．０５），ＥＨ组ＤＤ基因型和Ｄ等位基因频率增加。结论汉族ＥＨ发病与ＡＣＥ基因Ｉ／Ｄ多态性相关联，基因型ＤＤ和等位基因Ｄ可能是ＥＨ发病的易患因素     

血管紧张素转化酶基因多态性对血清血管紧张素转化酶水平及血脂的影响

为探讨血管紧张素转化酶基因多态性对本地人群高血压患者和正常人血清血管紧张素转化酶及血脂水平的影响,采用聚合酶链反应技术,对118例高血压患者和98例正常人的血管紧张素转化酶基因插入/缺失多态性进行分型,并检测血清血管祭张素转化酶活性及血脂含量。结果发现,高血压组血管紧张素转化酶三种基因型(缺失纯合子型、插入纯合子型和杂合子型)及插入/缺失等位基因的频率与正常对照组比较差异无统计学意义(X2=0.468,P=0.791;X2=0.379,P=0.538)。血清血管紧张素转化酶活性在三种基因型之间差异有显著性意义(F=17.107,P=0.000)。高血压组总胆固醇、低密度脂蛋白胆固醇、脂蛋白(a)高于正常对照组(P<0.05);高血压组三种基因型之间血脂各指标含量及正常对照组三种基因型之间总胆固醇、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇和载脂蛋白B含量差异有显著性意义(P<0.05)。此结果提示,血管紧张素转化酶基因多态性与血清血管肾张素转化酶活性及血脂含量有关,缺失纯合子型高血压患者血清血管紧张素转化酶活性最高且易患高脂血症。     

Association of polymorphism in the promoter region of the apolipoprotein E gene with diastolic blood pressure in normotensive Japanese.

The epsilon4 allele of apolipoprotein E (APOE) is reported to be a genetic risk factor of atherosclerosis through hyperlipidemia and late-onset Alzheimer's dementia. A recent report showed that a genetic variant (A -491T) in the promoter region of the APOE gene increases the risk of Alzheimer's disease. In the present study, we examined whether these APOE polymorphisms were genetically involved in essential hypertension. Japanese hypertensives (n=180) with a family history of hypertension and normotensive controls (n=195, sex and age matched with hypertensives) were recruited from the outpatients of Osaka University Hospital, and an informed consent to participate in the study was obtained from each person. APOE polymorphisms were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The frequencies of the A -491 allele in hypertensives and normotensives were 0.98 and 0.97, respectively, and the TT/-491 genotype was not found in either group. No significant differences between hypertensives and normotensives were observed in allele frequencies in either APOE polymorphism; however, the mean diastolic blood pressure in normotensive subjects with AA/-491 was significantly higher than in the subjects with AT/-491 (p < 0.01). These results suggest that the presence of the APOE promoter polymorphism is not a major risk factor for hypertension but that it does have some minor effect on basal blood pressure variation.     

Importance of the renin system for determining blood pressure fall with acute salt restriction in hypertensive and normotensive whites

Hypertensive (n=93) and normotensive (n=39) white individuals were given a high sodium intake of approximately 350 mmol/d for 5 days followed by a low sodium intake of 10 to 20 mmol/d for 5 days. With this acute and large reduction in salt intake, no significant change was seen in blood pressure in the normotensive individuals, but blood pressure decreased in the hypertensive individuals. Compared with normotensive subjects, hypertensive patients had a 7/7-mm Hg greater fall in blood pressure (P<0.05 for systolic and P<0.01 for diastolic, adjusted for age), with similar changes in urinary sodium excretion. From the high-salt to low-salt diet, plasma renin activity rose from 0.90 to 5.99 ng. mL(-1). h(-1) in normotensives, whereas in hypertensives it rose from 0.73 to only 3.14 ng. mL(-1). h(-1) (P<0.05 between hypertensives and normotensives). Plasma aldosterone rose by 1396 pmol/L in normotensive subjects and by 511 pmol/L in hypertensive patients (P<0.05). Significant inverse correlations were obtained for all subjects between the fall in blood pressure from the high-salt to low-salt diet and the rise in plasma renin activity and aldosterone that occurred in addition to the absolute level on the low-salt diet. These results demonstrate that the larger fall in blood pressure with an acute reduction in salt intake in hypertensives compared with normotensives is, at least in part, due to a less-responsive renin-angiotensin-aldosterone system in the hypertensive patients.     

AT_1R基因多态性对血压的影响

目的 检测血管紧张素Ⅱ的Ⅰ型受体(AT_1R)C1166等位基因在正常人和原发性高血压(EH)患者中的频率,并研究中国汉族人AT_1R基因多态性与原发性高血压的关系.方法 测定120例汉族原发性高血压病人和86个汉族正常人的血压、体重指数、空腹血糖及血胆固醇和甘油三酯浓度.用盐析法提取外周血白细胞DNA,用PCR加上限制性酶切方法检测AT_1R的C1166位基因突变.结果 高血压组除收缩压、舒张压显著高于对照组外,其它临床指标如体重指数、空腹血糖及血脂水平两组间无显著差异;EH患者AT_1R基因AC基因型频率比正常对照组高(0.081vs 0.058,P<0.01),C1166等位基因频率EH组高于正常对照组(0.091vs 0.029,P<0.05);两组中均未发现CC纯合子基因型;进行性别分组后,发现在女性EH患者C1166等位基因频率高于女性正常对照组(0.125 vs 0. 031,P<0.05),在男性EH患者C166频率与男性正常对照组无显著差异(0.072vs O.028,P>0.05);将EH组分为有、无高血压家族史两组,发现有高血压家族史的EH患者C1166频率高于无家族史EH患者(0.123 vs 0.035,P<0.05).结论 在中国汉族人群中,AT_1R基因多态性与原发性高血压有关;C1166等位基因可能是一个高血压的易感基因,并与有家族史的原发性高血压以及女性高血压病密切相关.     

−344C/T polymorphism of CYP11B2 gene in Italian patients with idiopathic low renin hypertension

Most patients with low renin essential hypertension are not qualitatively different from patients with idiopathic hyperaldosteronism, as in both conditions aldosterone secretion is not appropriately reduced. The aim of the study was to investigate allele and genotype frequencies of the −344C/T polymorphism, located in the promoter region of the aldosterone synthase gene, in 83 patients with idiopathic low renin hypertension characterized by an increased aldosterone to renin ratio, including both patients with low renin essential hypertension (n = 53) and subjects with idiopathic hyperaldosteronism (n = 30), compared with 78 patients with normal to high renin essential hypertension and 126 normotensive control subjects. The relationship of −344C/T genotypes to basal and post-captopril plasma aldosterone/plasma renin activity ratio was also examined in the entire hypertensive population. An increased frequency of the T allele and a relative excess of TT homozygosity over CC homozygosity were found in patients with idiopathic low renin hypertension in comparison with both normal to high renin hypertensives and normotensive controls. A higher post-captopril aldosterone to renin ratio was found in the hypertensives with TT genotype than in those with CC genotype, and TT+TC genotypes were associated with a smaller decrease in the aldosterone-to-renin ratio elicited by captopril administration. The present study suggests that the −344C/T polymorphism, or a functional variant in linkage disequilibrium with it, may play a role in the abnormal regulation of aldosterone secretion in idiopathic low renin hypertension.     

Different frequencies of inducible nitric oxide synthase genotypes in older hypertensives

A locus for essential hypertension has been found recently on chromosome 17 in the general vicinity of the inducible nitric oxide synthase (iNOS) gene (NOS2A at 17cen-q11.2). We therefore tested NOS2A markers for association and linkage with hypertension in affected Australian Anglo-Caucasians. Patients for the association study (n=112) were from our cohort of hypertensives (systolic/diastolic=175+/-25 SD/112+/-19 mm Hg) who were the offspring of 2 hypertensive parents; control subjects (n=164) were normotensives whose parents were both normotensive. The linkage study involved 156 hypertensive sib-pairs. Genotypes for an 8-allele pentameric repeat located 2.6 kb upstream of NOS2A and of a biallelic tetranucleotide repeat 0.7 kb upstream were determined by polymerase chain reaction and automated gene scan analysis. In the association study, the frequency of the minor allele of the biallelic marker was 0.18 in the hypertensives and 0.14 in the normotensives (chi21 df=1.1, P=0.3). Allele frequencies for the multiallelic marker were also similar in each group (chi2 7 df=9.8, P=0.2). Furthermore, no genotypic differences in blood pressure were apparent. In the sib-pair study, SPLINK APM, and MAPMAKERS/SIBS did not indicate excess allele sharing. We also examined genotype as a function of age. In the younger (< 60 years) hypertensives as well as younger or older normotensives, genotype and allele frequency of the biallelic marker was similar (0.12 to 0.14). However, in hypertensives >/=60 years of age, frequency of the minor allele was 0.28 (chi2=7.4, P=0.006). Homozygotes for this allele were rare. Frequency of heterozygotes was 0.19 for normotensives but 0.39 for the older hypertensives (chi2=8.0, P=0.018) and was 0.40 for hypertensive sibs >/=60 years of age with a diastolic pressure >/=100 mm Hg. Furthermore, homozygotes for the major allele were 7 years younger than heterozygotes (P=0.05 by ANOVA). In conclusion, the present study shows (1) no evidence for a role of NOS2A in hypertension and (2) a genotypic difference in frequency of a NOS2A promoter variant in older hypertensives, seen in 2 different cohorts. A possible interpretation of the latter observation is that NOS2A genotype could affect longevity, at least in patients at high risk by having moderate to severe hypertension.     

不同性别血管紧张素转化酶基因型与原发性高血压相关性研究

目的 :探讨男、女不同性别的血管紧张素转化酶 (ACE)基因型与原发性高血压 (EH)的相关关系。方法 :应用聚合酶链反应 (PCR)技术检测 12 8例男性 (其中EH患者 73例 ) ,79例女性(其中EH患者 4 3例 )ACE基因插入 /缺失 (I/D)多态性。结果 :男性组EH患者DD基因型频率(0 .35 6 )和D等位基因频率 (0 .5 75 )显著高于对照者 (0 .182和 0 .4 2 7,分别P <0 .0 5 ,<0 .0 2 )。且ACEDD基因型与男性EH患者的收缩压和脉压增高有关 (P <0 .0 5 )。而女性ACE基因型与EH及血压无显著相关性存在 (均P >0 .0 5 )。结论 :ACE基因I/D多态性对男性EH的发生及血压的增高有显著影响 ,而对女性无此作用。