Meta-analysis of the association of 4 angiotensinogen polymorphisms with essential hypertension: a role beyond M235T?

Angiotensinogen (AGT) gene polymorphisms have been linked to increased risk of hypertension, but the data remain controversial. In this study we review the most commonly investigated polymorphisms at the AGT locus (other than M235T) and provide summary estimates regarding their association with essential hypertension, while addressing heterogeneity, as well as publication biases. Data on 26 818 subjects from 46 studies for the 4 most-studied AGT variants (T174M in exon 2 and 3 promoter variants: A-6G, A-20C, and G-217A) were meta-analyzed. Statistically significant associations with hypertension were identified for the T174M (odds ratio [OR]: 1.19; 95% CI: 1.07 to 1.33; P=0.002) and G-217A (OR: 1.37; 95% CI: 1.17 to 1.59; P=0.00006) polymorphisms. A dual but consistent effect was observed for the -20C allele, which was associated with a decreased risk of hypertension in populations of mixed and European ancestries (OR: 0.64; 95% CI: 0.44 to 0.92; P=0.02 and OR: 0.77; 95% CI: 0.65 to 0.91; P=0.003, respectively), but with a 24% increase in the odds of hypertension in Asian subjects (OR: 1.24; 95% CI: 1.04 to 1.48; P=0.02). No association of the A-6G variant with hypertension was detected. Current studies support the notion that single variants at the AGT might modulate the risk of hypertension but indicate caution in interpreting these results because of the putative presence of publication bias and gene-environment interactions.     

Angiotensinogen promoter haplotypes are associated with blood pressure in untreated hypertensives

BACKGROUND: The polymorphic angiotensinogen (AGT) gene is one of the most promising candidates for blood pressure (BP) regulation and essential hypertension. OBJECTIVES: To investigate whether AGT haplotype analysis adds significant information compared to single polymorphism analysis with respect to different BP phenotypes in an untreated hypertensive sample. METHODS: Two hundred and twelve untreated hypertensive subjects of Caucasian origin were genotyped for the AGT polymorphisms C-532T, A-20C, C-18T, and G-6A. RESULTS: In single variant analyses, untreated hypertensives, carrying the AGT -532T or -6A alleles had significantly higher systolic blood pressure (SBP) and diastolic blood pressure (DBP), as well as ambulatory BP values compared to respective non-carriers. In haplotype-based analyses, combining all four AGT promoter variants, we demonstrate that AGT haplotypes containing different allele combinations at positions -532 and -6 were significantly associated with different BP values: (1) -532T and -6A with higher, (2) -532C and -6G with lower, (3) -532C and -6A with intermediate BP values. Since the result for the -532C/-20A/-18C/-6G haplotype was due to differences between non-carriers and carriers of this haplotype on both chromosomes, a recessive inheritance model for BP effects could be assumed. CONCLUSIONS: Our results designate the C-532T and G-6A as the best candidates for functional studies on the AGT gene. Haplotype-based analyses should greatly aid in the dissection of the genetic basis of complex traits, such as BP regulation and hypertension.     

Die Rolle des Angiotensinogengens für die essentielle Hypertonie

Essential hypertension is a complex disease influenced by different genetic and environmental factors. The renin-angiotensin system (RAS) is implicated in blood pressure regulation. Angiotensinogen (AGT) is the precursor of the biologically active angiotensin II (Ang II). Initial studies on hypertensive siblings and case-control studies indicated the important role of the angiotensinogen gene (AGT) for the predisposition to essential hypertension, preeclampsia and obesity-related hypertension. Recently, different AGT polymorphisms had been identified and analyzed in case-control studies. The aim of present studies is the analysis of potentially functional AGT variants (C-532T, G-6A), which might be responsible for the regulation of gene expression and therefore AGT generation. The A-6 allele is in complete linkage disequilibrium with the T235 allele and is associated with higher AGT expression in vitro. Segregation linkage analysis demonstrated that the C-532T polymorphism influences plasma AGT variability more significantly than the G-6A variant. Since the C-532T polymorphism is located within a AP-2 consensus element, functional promoter analyses are required. The understanding of the molecular basis of RAS in essential hypertension may provide us with new and more specific pharmacological agents and perhaps the ability to individualize antihypertensive treatment.     

Polymorphisms in the promoter region of the angiotensinogen gene are associated with liver cirrhosis in patients with chronic hepatitis B

BACKGROUND AND AIMS: It is known that the renin-angiotensin system (RAS) regulates fibrosis. Polymorphisms in the genes of the RAS may contribute to the outcome of liver cirrhosis. Angiotensinogen (AGT), mainly produced in the liver, is the substrate of renin. The aim of this study was to determine whether polymorphisms in the promoter region of the AGT gene are associated with liver cirrhosis in patients with chronic hepatitis B. METHODS: Restriction fragment length polymorphism PCR was used to study polymorphisms in the promoter region of the AGT gene in patients with liver cirrhosis and in a control population. Four polymorphisms were assayed: G-217A, G-152A, A-20C and A-6G. RESULTS: A statistically significant relationship was seen between polymorphisms of the AGT core promoter region and liver cirrhosis in patients with chronic hepatitis B (A-20C, P = 0.007; A-6G, P = 0.042). However, the distributions of the AGT-217 and AGT-152 genotypes were not significantly different from the control population (P = 0.615 and P = 0.170, respectively). CONCLUSIONS: Polymorphisms of the core promoter region of the AGT gene (AGT-20 and AGT-6) were associated with liver cirrhosis in patients with chronic hepatitis B.     

Relationship between the M235T and G(-6)A polymorphisms of the angiotensinogen gene

AIMS: Previous studies have reported tight linkage disequilibrium between the T235 and the A(-6) molecular variants of the angiotensinogen gene. This study was designed primarily to ascertain whether a similar relationship exists between the M235 and the G(-6) variants of the gene. We have investigated the degree of agreement between the genotypes of the M235T and the G(-6)A polymorphisms in two ethnic groups. METHODS: Subjects were an heterogeneous group of normotensive and hypertensive subjects of Caucasian (n = 77) and Afro-Caribbean (n = 51) origin. DNA was extracted from whole blood and was genotyped for both the M235T and G(-6)A polymorphisms using PCR-based methods. RESULTS: The distribution frequencies of the MM, MT, and TT genotypes were 0.39, 0.42, and 0.20 in white subjects, and 0.09, 0.17, and 0.74 in black subjects, respectively (chi-square, P < 0.0001). The distribution of AA, GA, and GG genotypes also differed between the two groups as follows: 0.22, 0.48, and 0.30 in white subjects, and 0.82 and 0.18 and 0 in black subjects respectively (chi-square, P < 0.0001). The agreement for TT-AA, MT-GA, and MM-GG was 93%, 91%, and 76% respectively in white and 100%, 67% and 0% respectively in black subjects. CONCLUSIONS: The results indicate ethnic differences in the distribution of both M235T and G(-6)A genotypes. The trend towards a decrease in the degree of agreement in the order of TT-AA > MT-GA > MM-GG suggests that linkage disequilibrium between the M235 and G-6 variant does not mirror that observed with the T235 and A-6 variants. These observations may have significant implications regarding the associations between the G(-6)A polymorphism and hypertension. However, this needs to be further investigated.     

简化的血管紧张素原基因单倍型分析与原发性高血压的关系

目的探讨血管紧张素原(AGT)基因连锁不平衡状态、单倍型及与原发性高血压的关系。方法选取497例病例对照样本,采用。PCR-RFIP法检测AGT基因7个位点多态性,同时用最大期望值(EM)算法进行两位点连锁不平衡和单倍型结构估计。结果A-6G,C 31T,T235M三位点两两存在完全连锁不平衡(D’=1)。用5种多态(A-217G,G-152A,A-20C,T174M和T235M)和7种多态(A-217G,G-152A,A-20C,A-6G,C 31T,T174M)估计单倍型结果相同。病例对照研究发现单倍型H2在病例组中频率高于对照组;单个位点分析未见与高血压关联。结论AGT基因研究中A-6G,C 31T,T235M三种多态可简化为其中一种;H2单倍型可能与控制血压的保护性因素连锁不平衡。     

血管紧张素原基因和血管紧张素转换酶基因多态性与高血压

目的　研究中国人群中血管紧张素原 (AGT)基因单核苷酸多态性 (SNP)及血管紧张素转换酶 (ACE)基因插入 /缺失多态与高血压病的关系。方法　在 3 4 5例高血压病患者与 2 0 6名血压正常人中采用PCR RFLP法检测AGT基因A 2 0C ,A 6G和M 2 3 5T的多态性 ,用PCR法检测ACE基因 16内含子Alu片段插入 /缺失多态 ,同时用EM算法进行两位点连锁不平衡分析。结果　在M 2 3 5T和A 2 0C ,M 2 3 5T和A 6G ,A 2 0C和A 6G位点观察到了连锁不平衡 (P <10 - 4)。病例 对照检验显示T2 3 5等位基因频率在高血压组中高于对照组 ,且高血压病患者中ACE (DD +ID) +AGT TT2 3 5基因型频率高于对照组。结论　受检人群中AGT基因各多态频率处于两两连锁不平衡 ,但AGT基因即T2 3 5位点以隐性作用方式与高血压关联 ,T2 3 5等位基因与ACE D等位基因在高血压病发生中具协同作用     

Angiotensinogen gene and essential hypertension in the Japanese: extensive association study and meta-analysis on six reported studies.

BACKGROUND: Accumulating evidence has supported the pathophysiological role of angiotensinogen in essential hypertension. However, some studies of molecular genetics have implicated that there may be an ethnic variation concerning the disease susceptibility of the AGT gene. OBJECTIVES AND METHODS: To evaluate the importance of this candidate gene for hypertension, we undertook an extensive association study in the Japanese. This case-control study was conducted in a total of 1232 individuals consecutively enrolled in a single institution, divided into two subgroups: one subgroup comprised 254 hypertensive and 224 normotensive subjects and the other comprised 463 hypertensive and 291 normotensive subjects. A meta-analysis was subsequently performed on six Japanese studies including the present study. RESULTS: No significant association was observed between a molecular variant of AGT, Thr235, and hypertension status in our case-control study. Moreover, this finding was extendible to another AGT polymorphism, G-6A, one of the potential functional polymorphisms in the promoter region, because these two polymorphisms proved to be in complete linkage disequilibrium in the studied population. The meta-analysis revealed that the pooled estimate of the odds ratio across the studies was 1.22 (95% CI 1.05-1.42), and that there was significant evidence against homogeneity of the odds ratios among the studies included (phi2 = 19.8, df = 5, P = 0.0014). In particular, a large range of variation (60-83%) was found for the allele frequency of Thr235 among control subjects of the six Japanese case-control studies. CONCLUSIONS: Although the meta-analysis appears in favour of association between the AGT variant and essential hypertension in the Japanese, there is considerable heterogeneity among the studies and the evidence is also rather borderline. Further comprehensive approaches are needed to resolve this debatable issue.     

Association of angiotensinogen M235T and A(-6)G gene polymorphisms with coronary heart disease with independence of essential hypertension: the PROCAGENE study. Prospective Cardiac Gene

OBJECTIVES: We examined the relationship between the angiotensinogen (AGT) gene M235T polymorphism, the variant promoter of the AGT gene A(-6)G and the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and coronary heart disease (CHD) in native Gran Canaria Island habitants, who have the highest rates of CHD in Spain. BACKGROUND: Some studies subject that the ACE (I/D) polymorphism could be associated with CHD, while AGT (M235T) has been related to essential hypertension. METHODS: We studied 304 subjects with angiographic evidence of coronary artery disease and a clinical diagnosis of myocardial infarction or unstable angina and 315 age- and gender-matched controls. Blood was drawn and DNA extracted. Angiotensin-converting enzyme (I/D) gene polymorphism was analyzed by polymerase chain reaction (PCR) and AGT gene polymorphisms by restriction fragment length polymorphism-PCR and mutagenically-separated PCR. RESULTS: The ACE (I/D) polymorphism showed no association with CHD, whereas the frequency distribution of AGT (M235T) genotypes among patients and controls (235T: 29.1% and 19.0%; M235T: 48.5% and 50.2%; M235: 22.4% and 30.8%, respectively) was statistically different (p = 0.005) and not related to the presence of essential hypertension. Similar results were observed with the AGT A(-6)G polymorphism. In multiple logistic regression analysis, CHD odds ratio associated with 235T and M235 homozygotes were 1.7 (1.1 to 2.6) and 0.54 (0.36 to 0.82), respectively. CONCLUSIONS: This study shows that genetic variation of the AGT (M235T), but not the ACE (I/D), genotypes contributes to the presence of CHD independently of blood pressure profile in a subset of the Spanish population with a high prevalence of cardiovascular disease.     

血管紧张素原基因启动子区域单核苷酸多态与高血压并发冠心病的关系

目的　研究在中国南方汉人群中 ,血管紧张素原基因 (angiotensinogen ,AGT)启动子区域 2 17位和 2 0位上的二种单核苷酸多态与高血压病 (EH)并发冠心病的关系。方法　运用多重SNaPshot反应 ,对 2 0 5例EH并发冠心病患者、185例EH患者和 185名健康对照者进行G 2 17A和A 2 0C多态基因分型。结果　G 2 17A多态的基因型分布在EH并发冠心病组 (AA =8、AG =71、GG =12 6 )和对照组 (AA =8、AG =37、GG =14 0 )之间有显著性差异 (P =0 0 0 5 ) ;A、G等位基因频率与对照组相比亦有显著性差异 (A 2 1 2 2 %、G 78 78%比A 14 32 %、G 85 6 8% ,P =0 0 12 ) ;A 2 0C多态的基因型分布 (CC、AC、AA)及C、A等位基因频率在二组间的差异无显著性 (分别为CC =5、AC =4 9、AA =15 1比CC =2、AC =6 1、AA =12 2 ,P =0 0 97;C 14 39%、A 85 6 1%比C 17 5 7%、A 82 4 3% ,P=0 2 2 6 )。在男性EH并发冠心病组中 ,G 2 17A和A 2 0C多态的基因型分布及其等位基因频率与对照组相比均有显著性差异 (G 2 17A :AA =7、AG =5 3、GG =86比AA =6、AG =2 8、GG =97,P =0 0 2 2 ;A 2 2 95 %、G 77 0 5 %比A 15 2 7%、G 84 73% ,P =0 0 2 2。A 2 0C :CC =3、CA =2 7、AA =116比CC =2、CA =4 3、AA =86 ,P =0 0 2 3;C 11 30 %     

Interaction of gender, hypertension, and the angiotensinogen gene haplotypes on the risk of coronary artery disease in a large angiographic cohort

There is increasing evidence suggesting the importance of evaluating gene-environment interactions in the genetic study of coronary artery disease (CAD). We investigated the association of multiple single nucleotide polymorphisms in the angiotensinogen (AGT) gene with CAD, considering the interaction between the genetic and non-genetic factors, using a larger and ethnically homogeneous angiographic cohort. A total of 1254 consecutive patients who underwent cardiac catheterization (735 with CAD and 519 without) were recruited. T174M (rs4762), M235T (rs699), G-6A, A-20C, G-152A, and G-217A polymorphisms of the AGT gene were genotyped. We used a regression approach based on a generalized linear model to evaluate haplotype effects defined by the multilocus data and detection of gene-environment interaction by incorporating interaction terms in the model. We found significant differences in global AGT gene haplotype profile between patients with and without CAD (the global score statistic=25.411, P=0.008). Significant interactions between AGT gene haplotypes, gender and hypertension were detected. We also used haplotype counting to directly estimate the odds ratio of each AGT gene haplotype, and found that the effects of haplotypes were markedly different in subgroups defined by gender and hypertension, providing strong evidence of gene-environment interaction. Female gender synergistically enhances (or male gender reverses) the effects of AGT gene haplotypes on the risk of CAD in the presence of hypertension. In conclusion, the effect of AGT gene haplotypes on the risk of CAD was significantly increased in women with hypertension, which highlights the importance of evaluating gene-environment interactions in the genetic study of CAD.     

血管紧张素原基因启动子区域单核苷酸多态性与心肌梗死的相关性

为研究血管紧张素原基因启动子区域 - 2 17、- 2 0位和 - 6位上的三种单核苷酸多态性与心肌梗死的相关性 ,采用多重SnaPshot反应 ,在中国南方汉人群中 ,对 2 16例心肌梗死患者和 185名健康对照者进行G 2 17A ,A 2 0C和G 6A多态基因分型。结果发现 ,G 2 17A多态AA、AG和GG基因型分布和A、G等位基因频率在心肌梗死组与对照组之间相比有显著性差异 (分别为 10、77、12 9比 8、37、14 0 ,P =0 .0 0 2 ;2 2 .4 5 %、77.5 5 %比 14 .32 %、85 .6 8% ,P=0 .0 0 3)。G 6A多态AA、AG和GG基因型分布在心肌梗死组和对照组之间亦有显著性差异 (分别为 14 7、6 4、5比12 7、4 4、14 ,P =0 .0 2 9) ,但A、G等位基因频率在两组间无显著性差异 (P =0 .394 )。A 2 0C多态CC、AC和AA基因型分布在两组间有差异 (分别为 6、5 1、15 9比 2、6 1、12 2 ) ,但无统计学意义 (P =0 .0 6 7) ,C、A等位基因频率在两组间亦无显著性差异 (P >0 .0 5 )。Logistic回归分析发现 ,年龄 (P =0 .0 0 1)、收缩压 (P =0 .0 13)和血浆甘油三酯浓度 (P =0 .0 10 )是该人群发生心肌梗死的独立危险因素 ,而高密度脂蛋白胆固醇 (P =0 .0 18)是一种保护因素。结果提示 ,在中国南方汉人群中 ,血管紧张素原基因G 2 17A和G 6A多态可能与心肌梗死的发生     

血管紧张素原基因核心启动子区域的单核苷酸多态与冠心病的关系

目的:在中国南方汉族人群中,检测血管紧张素原基因(AGT)5'端核心启动子内AGCE1区域的单 核苷酸多态(SNPs),并探讨其与冠心病发病的关系。方法:应用PCR直接测序技术检测AGCE1区域的序列,并 结合多重SNaPshot反应在145例血压正常的冠心病患者和185例健康对照者中对所检测的SNPs进行基因分 型。结果:在AGT基因AGCE1区域-20和-6位上发现2个SNPs,且A 20C和G 6A多态呈连锁不平衡。A 20C多态的基因型分布在冠心病组(CC=4,AC=29,AA=112)和对照组(2,61,122)之间差异有统计学意义(P <0.05)。C等位基因频率在两组间虽有差异(12.76%/17.57%),但未达到统计学意义(P>0.05)。G 6A多态 的基因型分布和等位基因频率在冠心病组与对照组之间差异均无统计学意义。单倍型分析表明,各组单倍型的 频率分布在两组间差异亦无统计学意义。结论:AGT基因的A 20C多态可能与血压正常人群的冠心病发病相 关。     

Genetic polymorphisms of angiotensinogen and essential hypertension in a Tibetan population.

The human angiotensinogen gene (AGT) is a promising candidate for an essential hypertension-susceptibility gene. We aimed to explore the single-locus, haplotype and epistasis patterns of three polymorphisms of AGT (A-20C, A-6G and M235T) and their relation to the risk of essential hypertension in a Tibetan population. The three polymorphisms were genotyped in 333 essential hypertension patients and 235 healthy controls on the basis of a door-to-door cross-sectional study. Genotyping was performed using polymerase chain reaction (PCR)-restriction fragment length polymerase (RFLP) and direct sequencing techniques. The data were analyzed using the EH/EH+ program and the multifactor dimensionality reduction (MDR) method. Our single-locus analysis revealed that except for a marginal, significant association of A-20C allele distribution, no significant association between genotype and allele distributions of the A-20C, A-6G, or M235T polymorphism of AGT and essential hypertension was found. In haplotype analysis, we found that the H(1) haplotype may be the risk-conferring factor for hypertension, even after the Bonferroni correction. In epistasis analysis, we selected the final best model, which included the A-20C and A-6G polymorphisms with a strong synergistic effect. This model had a maximum testing accuracy of 0.564 and a maximum cross validation consistency of 10 out of 10 (p=0.001). The present study thus provides evidence of a strong synergistic effect of the A-20C and A-6G polymorphisms of AGT, which were not found to be associated with essential hypertension in the single-locus analysis. Moreover, we have proposed a promising data-mining analytical method using the open-source MDR software package for detecting and characterizing gene-gene interactions.     

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.     

血管紧张素原基因多态性与高血压血尿醛固酮水平相关

目的研究血管紧张素原(Angiotensinogen,AGT)基冈5个单核苷酸多态性(single nucleotide polymorphisms,SNPs)及其构成的单倍型在中国汉族人群中与原发性高血压的相关性及各SNP与高血压患者血浆肾素活性(PRA)、血管紧张素Ⅱ(AngⅡ)、血浆和尿醛固酮(Ald)水平的关系。方法采用MassARRAYTM系统质谱检测技术,在500例原发性高血压患者和500名正常对照者中,对AGT基因启动子区域的C-532T、A-20C、G-6A及编码区的T174M和M235T进行基因分型。用放免法检测高血压患者PRA、AngⅡ、血尿Ald水平。结果5种SNP的等位基因频率和单倍型分布在原发性高血压组和对照组中均无显著差异(P>0．05);男性高血压患者中C-532T多态CT TT基因型个体尿Ald水平显著高于CC型个体(6．52 vs 5．19μg／d,P=0．03);女性高血压患者G-6A多态GG GA基因型个体血Ald水平显著高于AA型个体(78．63 vs 58．86 pg/ml,P=0．015);女性高血压患者M235T多态MM MT基因型个体血Ald水平显著高于TT型个体(78．73 vs 58．81 pg／ml,P=0．03); A-20C多态AC CC基因型与G-6A多态GG GA基因型联合者尿Ald水平(P<0．05)、体重指数(P <0．01)显著高于其他联合基因型。结论AGT基因5个SNP及单倍型分布在高血压患者和正常血压对照之间无显著差异,AGT基因的SNP分布与原发性高血压患者血尿醛固酮水平有关。     

Angiotensinogen gene polymorphisms M235T/T174M: no excess transmission to hypertensive Chinese

The gene encoding angiotensinogen (AGT) has been widely studied as a candidate gene for hypertension. Most studies to date have relied on case-control analysis to test for an excess of AGT variants among hypertensive cases compared with normotensive controls. However, with this design, nothing guarantees that a positive finding is due to actual allelic association as opposed to an inappropriate control population. To avoid this difficulty in our study of essential hypertension in Anqing, China, we tested AGT variants using the transmission/disequilibrium test, a procedure that bypasses the need for a control sample by testing for excessive transmission of a genetic variant from parents heterozygous for that variant. We analyzed two AGT polymorphisms, M235T and T174M, which have been associated with essential hypertension in whites and Japanese, using data on 335 hypertensive subjects from 315 nuclear families and their parents. Except in the group of subjects younger than 25 years, M235 and T174 were the more frequently transmitted alleles. We found that 194 parents heterozygous for M235T transmitted M235 106 times (P=0.22) and that 102 parents heterozygous for T174M transmitted T174 60 times (P=0.09). Stratifying offspring by gender, M235 and T174 were transmitted 60 of 106 times (P=0.21) and 44 of 75 times (P=0.17), respectively, in men, and 46 of 88 times (P=0.75) and 16 of 27 times (P=0.44), respectively, in women. Our results were also negative in all age groups and for the affected offspring with blood pressure values >/=160/95 mm Hg. Thus, this study provides no evidence that either allele of M235T or T174M contributes to hypertension in this Chinese population.     

The M235T polymorphism in the angiotensinogen gene is associated with the risk of malignant hypertension in white patients

BACKGROUND: Malignant hypertension can be considered an extreme phenotype of renin-mediated hypertension. Therefore, we compared the allelic frequencies of the angiotensinogen (AGT) M235T, angiotensin-converting enzyme insertion/deletion (ACE I/D) and angiotensin II-type I receptor (AT1R) A1166C polymorphisms in malignant hypertensive patients with hypertensive and normotensive controls. METHODS: A total of 101 consecutive patients between 1995 and 2005 admitted to a large university hospital fulfilled the criteria for malignant hypertension. Seventy-five patients (74%) were compared with 150 hypertensive and 150 normotensive controls, randomly selected from a population study and individually matched on age, sex and ethnicity. RESULTS: The odds of malignant hypertension in white subjects with the TT genotype of the AGT M235T polymorphism was 14.3 (5.5-37) compared to hypertensive controls, and 9.4 (3.8-23.2) compared to normotensive controls. Adjustment for age, sex, smoking and antihypertensive therapy did not affect this association. The association of AGT M235T with malignant hypertension was not significant in blacks. In patients with malignant hypertension, the TT genotype was associated with more severe renal dysfunction and microangiopathic haemolysis. No differences were found in allele frequencies of the ACE I/D or the AT1R A1166C polymorphisms between study groups. CONCLUSIONS: The TT genotype of AGT M235T is associated with malignant hypertension in whites, carriers having an odds of approximately 10 to 1 compared to hypertensive and normotensive controls. These observations may provide a better understanding of the pathophysiology of malignant hypertension and offer possibilities for identifying patients at risk. Larger association or linkage studies are needed for a more detailed risk assessment.     

Angiotensinogen M235T variant and salt sensitivity in young normotensive Caucasians.

BACKGROUND AND AIMS: A single-nucleotide variant of the angiotensinogen gene (AGT 235T) has been associated with essential hypertension and increased plasma levels of angiotensinogen. This variant may also serve as a genetic marker for the increased blood pressure response to dietary salt intake, but the relationship between AGT genotype and salt sensitivity has not been studied until now. We therefore examined the relationship between the AGT 235T genotype and the blood pressure response to short-term dietary salt restriction in young normotensive men. SUBJECTS AND METHODS: A total of 187 young normotensive men were characterized for family history of hypertension, salt sensitivity, plasma parameters of the renin-angiotensin system under high- and low-salt diets, and the AGT 235T genotype. RESULTS: While the T allele was significantly associated with a positive family history of hypertension (chi2 = 7.0; P< 0.03) and higher plasma angiotensinogen levels (P< 0.015) and renin activity (P < 0.037), blood pressure under both diets was not significantly affected by the AGT genotype. When the subjects were classified into salt-resistant and salt-sensitive groups, genotypic distribution was nearly identical between both groups (frequency of T allele: 0.45 versus 0.46). CONCLUSION: Our findings demonstrate that the AGT 235T allele is significantly associated with a positive family history of hypertension, but is not an important determinant of the blood pressure response to dietary salt intake in young normotensive subjects. It is therefore unlikely that the AGT 235T genotype can serve as an early genetic marker of salt sensitivity.