There is substantial evidence to suggest that BP (blood pressure) is an inherited trait. The introduction of gene technologies in the late 1980s generated a sharp phase of over-inflated prospects for polygenic traits such as hypertension. Not unexpectedly, the identification of the responsible loci in human populations has nevertheless proved to be a considerable challenge. Common variants of the RAS (renin–angiotensin system) genes, including of ACE (angiotensin-converting enzyme) and AGT (angiotensinogen) were some of the first shown to be associated with BP. Presently, ACE and AGT are the only gene variants with functional relevance, where linkage studies showing relationships with hypertension have been reproduced in some studies and where large population-based and prospective studies have demonstrated these genes to be predictors of hypertension or BP. Nevertheless, a lack of reproducibility in other linkage and association studies has generated scepticism that only a concerted effort to attempt to explain will rectify. Without these explanations, it is unlikely that this knowledge will translate into the clinical arena. In the present review, we show that many of the previous concerns in the field have been addressed, but we also argue that a considerable amount of careful thought is still required to achieve enlightenment with respect to the role of RAS genes in hypertension. We discuss whether the previously identified problems of poor study design have been completely addressed with regards to the impact of ACE and AGT genes on BP. In the context of RAS genes, we also question whether the significance of ‘incomplete penetrance’ through associated environmental, phenotypic or physiological effects has been duly accounted for; whether appropriate consideration has been given to epistatic interactions between genes; and whether future RAS gene studies should consider variation across the gene by evaluating ‘haplotypes’.

INTRODUCTION

A high proportion of the risk for cardiovascular events is attributed to hypertension [1]. Despite the host of antihypertensive agents presently available, there is little evidence to indicate that hypertension is appropriately controlled in either developed [2,3] or emerging [4] communities. The exact mechanisms responsible for a poor BP (blood pressure) control nevertheless remain elusive. The chances are that this represents a combination of psychosocial, socio-economic, environmental, physician-related and biological effects. However, apart from age and body size, the biological factors that account for most of the variation in BP at a population level remain obscure. Nevertheless, heritability analysis indicates that 15–60% of BP variability can be attributed to genetic effects [58].

With the introduction of novel gene technologies two decades ago, a veritable explosion of studies attempted to identify the genetic factors that play a role in hypertension. Not unexpectedly, this paradigm progressed rapidly through various phases of a ‘hype cycle’ [9], with a sharp peak of inflated expectations, followed by a predictably deep trough of disillusionment because of inconsistencies between studies. This disillusionment was expressed in publications voicing the concerns of scientific audiences worldwide [1013]. With the wealth of knowledge on the role of both the circulating and the tissue RAS (renin–angiotensin system) in BP control, it is not surprising that some of the first genes studied included those for molecules that control the RAS, with most of the work focusing on the ACE (angiotensin-converting enzyme) and AGT (angiotensinogen) genes. Indeed, much of the experience gained in the field of the polygenic mechanisms of BP control in human populations has been derived from these studies.

With little guidance as to the best approaches to employ in the field, but a huge interest in the role of the RAS in cardiovascular disease, it is not surprising that many of the inconsistencies between studies that generated a trough of disillusionment came from studies evaluating the role of the ACE and AGT genes in BP control in human populations. However, at the turn of the century, reflections on prior experiences [1013] provided better guidance as to the way forward. In the present review, we consider the current evidence for a role of the ACE and AGT genes in BP control in human populations in the context of whether previous concerns [1013] have been adequately addressed. Before we do so, it is important to first indicate the factors identified by experts in the field [1013] potentially contributing to inconsistencies in the scientific literature. We will subsequently focus the review on the scientific literature surrounding the potential role of ACE and AGT genes in hypertension or BP that address these issues. As there are numerous studies investigating the role of ACE and AGT genes as mediators of BP response to antihypertensive agents, and indeed at least two reviews to our knowledge have been published on this topic [13a,14], we will not discuss this issue in our present review.

FACTORS THAT REQUIRE CONSIDERATION WHEN ACCOUNTING FOR INCONSISTENCIES BETWEEN RAS GENE STUDIES

Expert opinions [1013] suggest that the following factors require consideration when attempting to account for inconsistencies between studies. Many of these factors are in keeping with rigorous scientific principles that should be applied to any human study.

(1) In view of the predicted small size effect that a single gene is likely to have in polygenic traits, studies should have large sample sizes and a priori statistical power calculations to justify the study size, including a consideration for the need to adjust for multiple comparisons if a number of genes are assessed in a specific sample. Furthermore, strong probability values should be observed. Consequently, in the present review, we will focus predominantly on studies evaluating the role of the ACE and AGT genes in BP control that could be considered to have large sample sizes (approx. 1000 or more participants). Smaller studies will only be discussed where unique approaches have been employed. Although often limited by the need to adjust for thousands of comparisons in some studies, we will also discuss the outcomes of large studies employing GWS (genome-wide scan) studies as well as large GWAS (genome-wide association studies), which consider genetic variations in or close to the ACE and AGT genes. In these studies, because adjustments for thousands of comparisons using standard approaches would exclude the potential of showing almost any gene contribution to a phenotype, the outcomes of all large GWS studies and GWAS will be discussed, even those with liberal statistical approaches to adjustments.

(2) Associations that make biological sense should be evaluated. In this regard, the functions of the ACE and AGT gene variants have been more extensively evaluated than other RAS genes and, although there is controversy with regard to the causal mutations, the associations between the ACE and AGT gene variants and circulating ACE or AGT concentrations are highly consistent, and a gene effect on BP is supported by studies involving manipulations of ACE and AGT genes in animals. These studies will be underscored in the present review. Importantly, this consideration does not apply to studies employing GWS or to GWAS.

(3) Data from family-based and population studies should be available, and must be replicated in independent samples. In this regard, study designs differ considerably, with some designs being more sensitive to detecting effects than others. The role of ACE and AGT genes in hypertension and BP control has been the subject of a variety of study designs. Some experts have expressed the opinion that case-control studies are sensitive to an inability to match the groups for genes other than those that contribute towards the phenotype of interest (population stratification) [13]. Nevertheless, more recent expert opinions have suggested that population stratification is only likely to make a meaningful difference if the control sample is obtained from an obviously different population than that from which the cases are derived (such as individuals of a different or mixed ethnic background, i.e. population admixture) [15]. Thus, in the present review, we discuss the outcomes of ethnically matched case-control studies on the ACE and AGT gene as being sound, as long as they fulfil other criteria such as a large study sample.

(4) Consistent with a polygenic trait, such as hypertension, the potential impact of genetic heterogeneity [13] (where inter-individual differences in environmental effects occur because of genetic background or where multiple genes produce the same effect) and incomplete penetrance through the effects of environmental or physiological influences [14,16] or alternative genes should be considered. In this regard, these issues have been explored for both the ACE and AGT genes and, although this paradigm is still in its infancy, these studies will also be described in the present review.

(5) High-quality phenotypic data should be available. This is presently the most contentious issue in our minds and is particularly important considering that most studies have employed conventional BP measurements or a diagnosis of hypertension as the outcome measure and few have reported on the quality of these assessments. Although the heritability of conventional BP is equivalent to 24-h BP in some studies [18], in other studies 24-h BP shows considerably greater heritability than does conventional BP [19,20]. Furthermore, ambulatory BP eliminates the chances of the inclusion of patients with a significant alerting response (white-coat effects) who may be labelled as hypertensive despite carrying a negligible cardiovascular risk [21]. Moreover, ambulatory BP allows us to identify patients with increased BP values either during the day or at night, but whose conventional BP may be normal (masked or isolated nocturnal hypertension), who nevertheless carry a considerable cardiovascular risk [21,22]. To date, few studies have evaluated the role of ACE or AGT genes as determinants of ambulatory BP or hypertension diagnosed using ambulatory BP. However, we will discuss the few studies that have evaluated relationships between ACE or AGT genotype and ambulatory BP in the context of the aforementioned considerations.

(6) The role of variations across the full gene on BP control, rather than a focus on the role of some genetic variations, should be explored [14]. In this regard, through recombinant events, groups of gene variants cluster in haplotype ‘bins’. Each haplotype ‘bin’ can be considered as an allele and these bins may be more sensitive to detecting relationships with the phenotypes of interest than do genotypes of individual variants. Importantly, despite haplotypes being constructed through the determination of multiple genotypes, the assessment of effects of haplotypes does not require adjustments for multiple genotyping. Haplotypes within both the ACE and AGT genes have been evaluated and these studies will be discussed.

THE ACE GENE

Rationale for considering a role for the ACE gene in BP control

In 1990, Rigat et al. [23] produced evidence to show that an I/D (insertion/deletion) polymorphism (variant) in intron 16 of the ACE gene was strongly associated with circulating ACE concentrations. Indeed, in people homozygous for the D allele (D/D genotype), plasma ACE concentrations were twice those of persons homozygous for the I allele (I/I genotype), whereas subjects heterozygous for the I/D variant had plasma ACE concentrations intermediate between the two, thus displaying a co-dominant effect of the gene. The same group subsequently showed, from combined segregation and linkage analysis, that the I/D variant does indeed control plasma ACE concentration [24].

Being a polymorphism in a region that is not translated, the potential that the I/D variant is not the causal mutation, but rather exists in linkage disequilibrium (inherited together with) with a variant elsewhere in the ACE gene, was considered. Thus, using further segregation and linkage analysis, the same group identified two quantitative trait loci (genetic regions related to a quantitative trait) that may account for the relationship between the I/D variant and plasma ACE concentrations [25]. In an attempt to identify the causal polymorphism associated with plasma ACE concentrations, further studies suggested that one of the two quantitative trait loci may involve either the I/D variant itself or an alternative variant downstream from the I/D polymorphism [4656(CT)2/3] [26] and excluded a mutation in exons 1–5 and introns 1–4 and part of intron 5 upstream from the I/D variant [27]. Subsequent fine mapping indicated that the functional mutation could not be the I/D variant, but was indeed a variant downstream from the I/D variant [28]. However, to date, the functional mutation in the ACE gene has not been identified. Nevertheless, there is worthy data to show that the ACE gene controls ACE concentrations. In this regard the 4656(CT)2/3 variant is strongly associated with plasma ACE concentrations [29], and a meta-analysis of small and large studies demonstrated consistent relationships between the I/D variant and plasma ACE concentrations and that people with the D/D genotype have an overall approx. 56% increase in ACE concentrations compared with those with the I/I genotype [30].

There is no question that human ACE is involved in BP control. Practitioners employ the clinical outcomes of this evidence daily when prescribing ACEIs (ACE inhibitors) as antihypertensive agents. However, is there direct evidence to show that the ACE gene can control BP? This is indeed the case, as, in 1995, Krege et al. [31] reported a dramatic 34 mmHg decrease in BP in male, but not female, mice in response to functional inactivation of the ACE gene.

Evidence for and against a role for the ACE gene in human BP control

Tables 1 and 2 summarize the characteristics of the major candidate gene studies that have evaluated the relationship between the ACE gene and human hypertension or BP that fulfil many of the criteria listed in points (1)–(6) described above. Table 1 shows the characteristics of the major studies showing linkage or an association of the ACE gene with BP or hypertension [3236], whereas Table 2 shows the characteristics of the studies providing evidence against a role for the ACE gene [30,3743]. Table 3 summarizes the characteristics of large GWS studies and GWAS which show a relationship between sites at or near the ACE locus and BP or hypertension [4453], whereas Table 4 summarizes the large GWS studies and GWAS which failed to show such relationships [5463]. It should be apparent that there are presently studies with considerable sample sizes that either support [3236,4453] or refute [30,3743,5463] a role for the ACE gene in controlling BP.

Table 1
Characteristics of major studies showing a relationship between the ACE gene and BP or hypertension

Details of points 1–6 are described in the text [1, n > 1000; 2, associations that make biological sense; 3, ethnically matched case-control studies (NA, not applicable, as not a case-control study); 4, context-dependent analysis; 5, high-quality BP data; and 6, haplotype analysis]. Con., Conventional; HT, hypertension.

Reference ACE gene variant Sample size (nStudy design Population sampled Phenotype assessed Effect 
Fornage et al. [32Microsatellite 1488 sibs Quantitative trait-based linkage analysis Mean age = 14.8 years; Caucasians; none receiving treatment Con. BP 37–53% of BP variance in males from gene (P< 0.04–0.005) ✓ ✓ NA ✓ ✓  
O'Donnell et al. [33Microsatellite I/D 1044 sib-pairs Quantitative trait-based linkage analysis Caucasians; Framingham adults; approx. 12–16% estimated to be receiving treatment Con. BP Linkage for DBP in men (P=0.02) ✓ ✓ NA ✓   
O'Donnell et al. [33I/D 3095 Cross-sectional family-based study Framingham adults HT OR for HT in men in favour of D/D = 1.59 (P=0.02) ✓ ✓ NA ✓   
Higaki et al. [34I/D 5014 Cross-sectional Japanese adults HT OR for HT in men in favour of D/D = 1.75 (P=0.0015) ✓ ✓ ✓ ✓   
Staessen et al. [35I/D 678 Prospective 12-year follow-up (median=9.1 years) family-based study Caucasians HT D/D had 31% greater chance of developing HT than did I/I (P=0.005)  ✓ NA  ✓ ✓ 
Di Pasquale et al. [36I/D 684 Prospective 6-year follow-up Caucasians HT HT developed in 23% D/D compared with 5.9 and 2.4% I/D and I/I respectively (P=0.0001)  ✓ ✓ ✓ ✓  
Reference ACE gene variant Sample size (nStudy design Population sampled Phenotype assessed Effect 
Fornage et al. [32Microsatellite 1488 sibs Quantitative trait-based linkage analysis Mean age = 14.8 years; Caucasians; none receiving treatment Con. BP 37–53% of BP variance in males from gene (P< 0.04–0.005) ✓ ✓ NA ✓ ✓  
O'Donnell et al. [33Microsatellite I/D 1044 sib-pairs Quantitative trait-based linkage analysis Caucasians; Framingham adults; approx. 12–16% estimated to be receiving treatment Con. BP Linkage for DBP in men (P=0.02) ✓ ✓ NA ✓   
O'Donnell et al. [33I/D 3095 Cross-sectional family-based study Framingham adults HT OR for HT in men in favour of D/D = 1.59 (P=0.02) ✓ ✓ NA ✓   
Higaki et al. [34I/D 5014 Cross-sectional Japanese adults HT OR for HT in men in favour of D/D = 1.75 (P=0.0015) ✓ ✓ ✓ ✓   
Staessen et al. [35I/D 678 Prospective 12-year follow-up (median=9.1 years) family-based study Caucasians HT D/D had 31% greater chance of developing HT than did I/I (P=0.005)  ✓ NA  ✓ ✓ 
Di Pasquale et al. [36I/D 684 Prospective 6-year follow-up Caucasians HT HT developed in 23% D/D compared with 5.9 and 2.4% I/D and I/I respectively (P=0.0001)  ✓ ✓ ✓ ✓  
Table 2
Characteristics of major studies that have failed to show a relationship between the ACE gene and BP or hypertension

Details of points 1–6 are described in the text [1, n > 1000; 2, associations that make biological sense; 3, ethnically matched case-control studies (NA, not applicable, as not a case-control study); 4, context-dependent analysis; 5, high-quality BP data (−, no details of BP measurements given); and 6, haplotype analysis]. Con., Conventional; HT, hypertension.

Reference ACE gene variant Sample size (nStudy design Population(s) sampled Phenotype assessed Effect 
Jeunemaitre et al. [37Microsatellite 169 sibs Linkage analysis Caucasians; all receiving treatment HT No linkage  ✓ NA  −  
Agerholm-Larsen et al. [38I/D 10150 Case-referent Caucasians; percentage receiving treatment not stated Con. BP No relationship with DBP or SBP in either gender group ✓ ✓ ✓ ✓ −  
Staessen et al. [39I/D 6923 Meta-analysis of case-control studies Caucasians HT No relationship with HT ✓ ✓ ✓  −  
Agerholm-Larsen et al. [30I/D 15942 (19 studies) Meta-analysis of case-control studies Caucasians Con. SBP No relationship with SBP ✓ ✓ ✓  −  
Castellano et al. [40I/D 2461 Cross-sectional Caucasians; 75% hypertensive HT No relationship with HT ✓ ✓ ✓  ✓ ✓ 
Matsubara et al. [41I/D 1245 and 803 Cross-sectional Japanese; approx. 30–40% receiving treatment Home BP and 24-h BP No relationship ✓ ✓ ✓ ✓ ✓  
Zaman et al. [42I/D 1340 Cross-sectional Japanese; approx. 30–40% receiving treatment Con. BP No relationship (but P=0.06 for DBP in men) ✓ ✓ ✓ ✓   
Mondry et al. [43I/D 1358 Case-control Caucasians HT No relationship with HT ✓ ✓ ✓ ✓  ✓ 
Reference ACE gene variant Sample size (nStudy design Population(s) sampled Phenotype assessed Effect 
Jeunemaitre et al. [37Microsatellite 169 sibs Linkage analysis Caucasians; all receiving treatment HT No linkage  ✓ NA  −  
Agerholm-Larsen et al. [38I/D 10150 Case-referent Caucasians; percentage receiving treatment not stated Con. BP No relationship with DBP or SBP in either gender group ✓ ✓ ✓ ✓ −  
Staessen et al. [39I/D 6923 Meta-analysis of case-control studies Caucasians HT No relationship with HT ✓ ✓ ✓  −  
Agerholm-Larsen et al. [30I/D 15942 (19 studies) Meta-analysis of case-control studies Caucasians Con. SBP No relationship with SBP ✓ ✓ ✓  −  
Castellano et al. [40I/D 2461 Cross-sectional Caucasians; 75% hypertensive HT No relationship with HT ✓ ✓ ✓  ✓ ✓ 
Matsubara et al. [41I/D 1245 and 803 Cross-sectional Japanese; approx. 30–40% receiving treatment Home BP and 24-h BP No relationship ✓ ✓ ✓ ✓ ✓  
Zaman et al. [42I/D 1340 Cross-sectional Japanese; approx. 30–40% receiving treatment Con. BP No relationship (but P=0.06 for DBP in men) ✓ ✓ ✓ ✓   
Mondry et al. [43I/D 1358 Case-control Caucasians HT No relationship with HT ✓ ✓ ✓ ✓  ✓ 
Table 3
Characteristics of major GWS studies and GWAS showing a relationship between sites at or near the ACE locus (located on chromosome 17) or the AGT locus (located on chromosome 1) and BP or hypertension

Details of points 1,3–6 are described in the text [1, n > 1000; 3, ethnically matched case-control studies (NA, not applicable, as not a case-control study); 4, context-dependent analysis; 5, high-quality BP data (−, no details of BP measurements given); and 6, haplotype analysis]. avg., average; Ch, chromosome; cM, centimorgan; Con., conventional; HT, hypertension; RAAS, renin–angiotensin–aldosterone system; RFLP, restriction fragment length polymorphism; SNP, single nucleotide polymorphism; *AGT locus is located on chromosome 1 and ACE locus is located on chromosome 17.

Reference Sample size (nStudy design Population(s) sampled Phenotype Effect 
Bielinski et al. [4410798 individuals (3320 families) GWS: 391 markers 10 cM apart Black, Hispanic, Asian and non-Hispanic white Americans Con. BP and PP PP: Ch1*, 106 cM, LOD = 2.4 (Blacks), Ch1, 212 cM, LOD = 2.7 (Blacks), Ch1, 201 cM, LOD = 2.2 (all race groups combined), Ch17, 89 cM, LOD = 3.6 (Hispanics) (LOD ≥ 2 considered significant) ✓ NA  ✓  
de Lange et al. [451109 dizygotic twins GWS: 737 markers equivalent to microsatellites 10 cM apart Whites, London Con. SBP Ch17, 70 cM, LOD = 1.8 (LOD > 0.8 considered significant at P<0.05) ✓ NA    
Gu et al. [4613524 individuals (4701 families) Association analysis on 387 microsatellite markers Blacks, non-Hispanic whites, Hispanics, Asian-Americans Con. BP or HT SBP: Ch17*, 100 cM, P=0.004 (Hispanics) DBP: Ch17, 100 cM, P=0.005 (Hispanics) ✓ NA  −  
Hottenga et al. [473472 twins and siblings GWS: 807 markers 5.6 cM apart (avg. for Australia); 383 markers 9.7 cM apart (avg. for The Netherlands) Australia, The Netherlands Con. DBP or ambulatory evening DBP Ch17, 43.1cM, LOD = 2.36, P=0.00049 Ch17, 109.8 cM, LOD = 1.24, P=0.0083 (thresholds defined as LOD > 1.18, P=0.01, for replicated loci; LOD > 2.2, P=0.00074 for new loci) ✓ NA  ✓  
Jacobs et al. [482413 individuals (family-based study) GWS: allele sharing estimated at approx. 2 cM intervals Framingham Con. SBP (prospectively for 30 years) Ch17, 109 cM, LOD = 5.32, P=0.0000048 (near ACE locus = Ch17, 95.23 cM) (P value set at <10−5✓ NA  ✓  
Levy et al. [491585 individuals (family-based study) GWS: markers 10 cM apart Framingham Con. BP (prospectively for 30 years) SBP: Ch17,94 cM, LOD = 2.2 (LOD >2 considered significant) (near ACE locus = Ch17, 95.23 cM) ✓ NA  ✓  
Rice et al. [50125 random+81 obese families (679 individuals) GWS: 353 microsatellite markers (mostly < 20 cM apart), 67 RFLPs Quebec, Canada Con. BP Ch1, AGT LOD = 1.21, P=0.009; Ch17, ACE, LOD = 1.06, P=0.014 (P value set at P<0.0023)  NA  ✓  
Wang et al. [511271 individuals from 373 pedigrees of young onset HT GWS for ACE activity: 479 microsatellite markers (10 cM apart) Taiwanese Con. BP Ch17, 89.6 cM LOD = 4.60 (LOD >3 considered significant]; near ACE locus (Ch17, 95.23 cM), influenced ACE activity ✓ NA  −  
Wilk et al. [521095 whites 1161 African Americans (family-based study) GWS: 391 microsatellite markers 10 cM apart Whites, African-Americans Age at diagnosis of HT Ch1, 123 cM, LOD = 1.48 (whites) Ch17, 127 cM, LOD = 1.65 (blacks) (LOD >1.0 considered significant) ✓ NA    
Levy et al. [531327 individuals (family-based study) GWAS: SNPs on Affymetrix 100 K GeneChip Framingham Con. BP (prospectively for 30 years) Weak evidence of association with SNPs in RAAS genes (SNP rs2478518 on AGT gene, P=0.021) ✓ NA  ✓  
Reference Sample size (nStudy design Population(s) sampled Phenotype Effect 
Bielinski et al. [4410798 individuals (3320 families) GWS: 391 markers 10 cM apart Black, Hispanic, Asian and non-Hispanic white Americans Con. BP and PP PP: Ch1*, 106 cM, LOD = 2.4 (Blacks), Ch1, 212 cM, LOD = 2.7 (Blacks), Ch1, 201 cM, LOD = 2.2 (all race groups combined), Ch17, 89 cM, LOD = 3.6 (Hispanics) (LOD ≥ 2 considered significant) ✓ NA  ✓  
de Lange et al. [451109 dizygotic twins GWS: 737 markers equivalent to microsatellites 10 cM apart Whites, London Con. SBP Ch17, 70 cM, LOD = 1.8 (LOD > 0.8 considered significant at P<0.05) ✓ NA    
Gu et al. [4613524 individuals (4701 families) Association analysis on 387 microsatellite markers Blacks, non-Hispanic whites, Hispanics, Asian-Americans Con. BP or HT SBP: Ch17*, 100 cM, P=0.004 (Hispanics) DBP: Ch17, 100 cM, P=0.005 (Hispanics) ✓ NA  −  
Hottenga et al. [473472 twins and siblings GWS: 807 markers 5.6 cM apart (avg. for Australia); 383 markers 9.7 cM apart (avg. for The Netherlands) Australia, The Netherlands Con. DBP or ambulatory evening DBP Ch17, 43.1cM, LOD = 2.36, P=0.00049 Ch17, 109.8 cM, LOD = 1.24, P=0.0083 (thresholds defined as LOD > 1.18, P=0.01, for replicated loci; LOD > 2.2, P=0.00074 for new loci) ✓ NA  ✓  
Jacobs et al. [482413 individuals (family-based study) GWS: allele sharing estimated at approx. 2 cM intervals Framingham Con. SBP (prospectively for 30 years) Ch17, 109 cM, LOD = 5.32, P=0.0000048 (near ACE locus = Ch17, 95.23 cM) (P value set at <10−5✓ NA  ✓  
Levy et al. [491585 individuals (family-based study) GWS: markers 10 cM apart Framingham Con. BP (prospectively for 30 years) SBP: Ch17,94 cM, LOD = 2.2 (LOD >2 considered significant) (near ACE locus = Ch17, 95.23 cM) ✓ NA  ✓  
Rice et al. [50125 random+81 obese families (679 individuals) GWS: 353 microsatellite markers (mostly < 20 cM apart), 67 RFLPs Quebec, Canada Con. BP Ch1, AGT LOD = 1.21, P=0.009; Ch17, ACE, LOD = 1.06, P=0.014 (P value set at P<0.0023)  NA  ✓  
Wang et al. [511271 individuals from 373 pedigrees of young onset HT GWS for ACE activity: 479 microsatellite markers (10 cM apart) Taiwanese Con. BP Ch17, 89.6 cM LOD = 4.60 (LOD >3 considered significant]; near ACE locus (Ch17, 95.23 cM), influenced ACE activity ✓ NA  −  
Wilk et al. [521095 whites 1161 African Americans (family-based study) GWS: 391 microsatellite markers 10 cM apart Whites, African-Americans Age at diagnosis of HT Ch1, 123 cM, LOD = 1.48 (whites) Ch17, 127 cM, LOD = 1.65 (blacks) (LOD >1.0 considered significant) ✓ NA    
Levy et al. [531327 individuals (family-based study) GWAS: SNPs on Affymetrix 100 K GeneChip Framingham Con. BP (prospectively for 30 years) Weak evidence of association with SNPs in RAAS genes (SNP rs2478518 on AGT gene, P=0.021) ✓ NA  ✓  
Table 4
Characteristics of major GWS studies and GWAS that have failed to show a relationship between sites at or near ACE locus (located in chromosome 17) or AGT locus (located in chromosome 1) and BP or hypertension

Details of points 1 and 3–6 are described in the text [1, n > 1000; 3, ethnically matched case-control studies (NA, not applicable, as not a case-control study); 4, context-dependent analysis; 5, high-quality BP data; and 6, haplotype analysis]. avg., average; Ch, chromosome; cM, centiMorgan; Con., conventional; HT, hypertension; RFLP, restriction fragment length polymorphism; SNP, single nucleotide polymorphism; *AGT locus is located on chromosome 1 and ACE locus is located on chromosome 17.

Reference Sample size Study design Population(s) sampled Phenotype Effect 
Adeyemo et al. [541054 individuals (from 188 families) GWS: markers 10 cM apart Rural Nigerians Con. BP No linkage with Ch1* or Ch17* (LOD >1.5 considered significant) ✓ NA    
Caulfield et al. [552101 affected sib-pairs GWS: markers 10 cM apart Whites (British ancestry) HT No linkage with Ch1* or Ch17* (LOD >1.57 considered significant or LOD >2 considered significant on strict criterion, correction for multiple genotyping) ✓ NA    
DeStefano et al. [568478 individuals (family-based study) GWS: markers 10 cM apart Framingham Con. PP (prospectively for 30 years) No linkage with Ch1* or Ch17* (LOD >2 considered significant) ✓ NA  ✓  
Morrison et al. [57338 white, 265 black hypertensive sibships GWS: 411 microsatellite markers approx. 8.4 cM apart Whites, blacks HT No linkage with Ch1* or Ch17* (LOD ≥1.5 considered significant) ✓ NA    
Morrison et al. [584404 individuals (275 hypertensive families) GWS: 387 microsatellite markers 10 cM apart African-Americans HT No linkage with Ch1* or Ch17* (LOD >2 considered significant) ✓ NA    
Adeyemo et al. [591017 individuals (family-based study) GWAS: 800000 SNPs (Affymetrix Genome-wide Human SNP array) African-Americans Con. BP or HT No association with SNPs in or near AGT or ACE (Bonferroni correction) ✓ NA  ✓  
Ehret et al. [602379 individuals from hypertensive probands GWAS for Ch1: 1569 SNPs in Ch1 (Affymetrix GeneChip) 1101 African-Americans, 1497 European-Americans Con. BP No association with SNPs in or near AGT (Bonferroni correction) ✓ NA    
Org et al. [611644 individuals (case-control study) GWAS: 395 912 SNPs (Affymetrix 500K GeneChip) Germans, Estonians Con. BP (repeated after 10 years) No association with SNPs in or near AGT or ACE (Bonferroni correction) ✓ ✓  ✓  
Sober et al. [621644 individuals (case-control study) GWAS: 2411 SNPs (Affymetrix 500K GeneChip) European ancestry (Southern Germany) Con. BP (repeated after 10 years) No association with SNPs in or near AGT or ACE (none of the SNPs achieved significance after Bonferroni correction) ✓ ✓  ✓ ✓ 
Wellcome Trust Case Control Consortium [63Approx. 2000 cases; approx. 3000 controls GWAS: 500568 SNPs (Affymetrix 500K GeneChip) British (European Caucasian ancestry) HT No association with SNPs in or near AGT or ACE (P value set at <5 × 10−7✓ ✓    
Reference Sample size Study design Population(s) sampled Phenotype Effect 
Adeyemo et al. [541054 individuals (from 188 families) GWS: markers 10 cM apart Rural Nigerians Con. BP No linkage with Ch1* or Ch17* (LOD >1.5 considered significant) ✓ NA    
Caulfield et al. [552101 affected sib-pairs GWS: markers 10 cM apart Whites (British ancestry) HT No linkage with Ch1* or Ch17* (LOD >1.57 considered significant or LOD >2 considered significant on strict criterion, correction for multiple genotyping) ✓ NA    
DeStefano et al. [568478 individuals (family-based study) GWS: markers 10 cM apart Framingham Con. PP (prospectively for 30 years) No linkage with Ch1* or Ch17* (LOD >2 considered significant) ✓ NA  ✓  
Morrison et al. [57338 white, 265 black hypertensive sibships GWS: 411 microsatellite markers approx. 8.4 cM apart Whites, blacks HT No linkage with Ch1* or Ch17* (LOD ≥1.5 considered significant) ✓ NA    
Morrison et al. [584404 individuals (275 hypertensive families) GWS: 387 microsatellite markers 10 cM apart African-Americans HT No linkage with Ch1* or Ch17* (LOD >2 considered significant) ✓ NA    
Adeyemo et al. [591017 individuals (family-based study) GWAS: 800000 SNPs (Affymetrix Genome-wide Human SNP array) African-Americans Con. BP or HT No association with SNPs in or near AGT or ACE (Bonferroni correction) ✓ NA  ✓  
Ehret et al. [602379 individuals from hypertensive probands GWAS for Ch1: 1569 SNPs in Ch1 (Affymetrix GeneChip) 1101 African-Americans, 1497 European-Americans Con. BP No association with SNPs in or near AGT (Bonferroni correction) ✓ NA    
Org et al. [611644 individuals (case-control study) GWAS: 395 912 SNPs (Affymetrix 500K GeneChip) Germans, Estonians Con. BP (repeated after 10 years) No association with SNPs in or near AGT or ACE (Bonferroni correction) ✓ ✓  ✓  
Sober et al. [621644 individuals (case-control study) GWAS: 2411 SNPs (Affymetrix 500K GeneChip) European ancestry (Southern Germany) Con. BP (repeated after 10 years) No association with SNPs in or near AGT or ACE (none of the SNPs achieved significance after Bonferroni correction) ✓ ✓  ✓ ✓ 
Wellcome Trust Case Control Consortium [63Approx. 2000 cases; approx. 3000 controls GWAS: 500568 SNPs (Affymetrix 500K GeneChip) British (European Caucasian ancestry) HT No association with SNPs in or near AGT or ACE (P value set at <5 × 10−7✓ ✓    

Linkage analysis

Overall, the linkage data better support [32,33] than refute [37] a role for the ACE gene. This conclusion is based on the fact that linkage with the ACE gene has been shown in two independent study populations [32,33] consisting of a markedly greater sample size (Table 1) than the study that failed to show linkage [37] (Table 2). Moreover, the linkage analysis showing a role for the ACE gene employed quantitative trait variance component-based linkage analysis (allele sharing non-parametric-based techniques) [32,33], which does not require a precise specification of the genetic models (unlike classical linkage analysis). Furthermore, linkage of the ACE gene to BP was observed for DBP (diastolic BP) in males only [32,33]. This supports the data showing a dramatic decrease in BP after functional inactivation of the ACE gene in male, but not female, mice [31]. In contrast, the study [37] that failed to show linkage of the ACE gene to hypertension did not assess gender-specific effects and did not employ a quantitative-based approach thus precluding analysis of DBP separate from SBP (systolic BP).

Major cross-sectional and other association studies

The cross-sectional population data that support a role for the ACE gene in men [33,34] is equally as strong as some of the data that refute a role for the ACE gene [38,41,42] in BP control. The total sample number for cross-sectional data favouring a role for the ACE gene is 8109 (Table 1) [33,34]. The total sample number for cross-sectional data refuting a role for the ACE gene in BP control is 15196 (Table 2) [38,41,42]. There is no particular striking shortcoming in most of the cross-sectional data either favouring [33,34] or refuting [38,41,42] a role for the ACE gene in BP control or hypertension. In the study by Agerholm-Larsen et al. [38] (Table 2), showing no relationship between the ACE I/D genotype and BP in 10150 subjects, the DBP values appeared to be higher (approx. 81–85 mmHg) than in other papers (approx. 78–81 mmHg) [33,34] showing a relationship between ACE genotype and BP. This suggests that different factors may be contributing to DBP in these populations. In the GENIPER study [40], performed in 2461 subjects (Table 2), the ACE I/D genotype was also not related to hypertension; however, the proportion of hypertensive subjects in that study (approx. 75%) is exceedingly high [40]. Furthermore, in the GENIPER study [40], ACE I/D allele frequencies differed in the north as compared with the south of Italy, suggesting population stratification, and effects on DBP were not assessed separately from SBP. In the Ohasama Study [41] in 1245 people, although no significant association between the ACE genotype and hypertension diagnosed with home BP measurements was observed, there was a trend effect in elderly males [OR (odds ratio) = 2.20 in D/D compared with I/I genotypes]. Furthermore, the impact of the ACE genotype on hypertension diagnosed on the basis of DBP measurements alone was not assessed [41]. In the Shibata Study conducted in 1340 Japanese [42] (Table 2), although the ACE I/D genotype was not associated with BP, the probability values for the multivariate adjusted relationships between the ACE I/D genotype and DBP in men was P=0.06. Furthermore, although Mondry et al. [43] in a case-control study of 1358 people have shown no relationship between the ACE I/D genotype and hypertension, no analysis of DBP or hypertension diagnosed on DBP alone was performed.

Meta-analyses

Meta-analyses conducted on a number of case-control studies do not support a role for the ACE gene I/D polymorphism in contributing toward hypertension or BP [30,39]. However, in these studies, the analyses were performed on pooled data from studies with different designs (case-referent, case-control, twin, cohort and family-based). Furthermore, in a meta-analysis [30], no gender-specific analysis was carried out on relationships with BP and, hence, these outcomes may have missed the ACE gene effect observed in males in other studies [3234]. In addition, one meta-analysis refuting a role for the ACE gene in BP control only showed data for SBP [30]. Consequently, the role of the ACE gene I/D polymorphism in DBP control, as suggested by other studies [3234], is not disproved [30].

Incidence studies

Evidence in favour of a role for the ACE I/D polymorphism is that there are presently two relatively large studies (n = 684 and 678) reporting the development of hypertension over 6–12-year follow-up periods [35,36] that indicate that the variant predicts the incidence of hypertension (Table 1). In contrast, there are no studies that have reported a lack of association between the ACE I/D variant and the incidence of hypertension. In the context of a field where cross-sectional data mostly rely on a diagnosis of hypertension being made by the presence of treatment and, hence, are subject to physician bias, incidence data are indeed a welcome enlightenment.

Genome-wide studies

There are nine GWS studies reporting linkage between sites at or near the ACE locus and BP or hypertension (Table 3), whereas there are five GWS studies which refute these relationships (Table 4). Importantly, for two of the GWS studies [48,49] supporting a role for the ACE gene, BP was measured prospectively over 30 years. Moreover, five of the nine supporting studies satisfied the criterion of high-quality BP data [point 5 above] (Table 3), whereas only one of the refuting studies [which assessed PP (pulse pressure)] satisfied this criterion (Table 4). Therefore it should be evident that the data from GWS studies better support than refute a role for sites at or near the ACE gene in BP or hypertension. Although the data from GWAS are clearly against a role for regions in or near the ACE gene (Table 4), the lack of associations have been attributed to possible inadequate marker coverage on GeneChips (46% of BP candidate genes are insufficiently covered on the Affymetrix 500K GeneChip) and an inability to detect small phenotypic effects of loci especially when using conservative statistics (Bonferroni corrections) [62].

With respect to the extent of linkage of regions close to or in the ACE locus on chromosome 17, other regions that have been shown to be in linkage with hypertension or BP have LOD (logarithm of the odds) scores that are very similar to the LOD scores achieved for chromosome 17 (Table 3). Moreover, in GWS studies, an analysis of the chromosomal regions that are most consistent in demonstrating linkage with hypertension or BP across studies, in seven of 14 studies chromosome 17, which contains the ACE gene, showed evidence of linkage, in five of 14 studies chromosome 18 showed evidence of linkage, and in four of 14 studies chromosomes 7, 10 and 15 showed linkage [4452,5458]. Thus, by far, the chromosomal region that contains the ACE gene is the most consistent region across studies to show linkage with hypertension or BP.

Summary

On the basis of the analysis of the major candidate gene studies shown in Tables 1 and 2 and discussed above, linkage studies (two studies) [32,33], cross-sectional studies (two studies which have been multivariate adjusted) [33,34] and incidence data (two studies which have been multivariate adjusted) [35,36] in large study samples (n = 684–5014) support a role for the ACE gene in contributing towards the variability of DBP in males or the development of hypertension in either men or women. The contribution described in these studies is not trivial, with the ACE genotype contributing 37–53% of the variance in BP in males [32], the odds of having hypertension (prevalence) being 1.59–1.75 times greater in D/D homozygotes than I/I homozygotes [33,34], and the odds of developing hypertension (incidence) being 23% in D/D homozygotes compared with 2.4% in I/I homozygotes [36], or 31% greater in the D/D homozygotes compared with the other ACE genotype groups [35]. Although it is unlikely that a single locus could account for as much as 53% of the inter-individual variation in a polygenic trait (such as mean arterial pressure), it should be noted that these data [32] were obtained in gender-specific analyses performed in siblings with a family history of hypertension, both of which would decrease inter-individual variation. Indeed, the ACE locus contributed to 29–33% of the inter-individual variance in BP in siblings with a family history of hypertension as opposed to more modest contributions of 13–16% in the whole group [32]. Nevertheless, further data are required to substantiate these findings.

On the basis of the analysis of the major GWS studies and GWAS shown in Tables 3 and 4, and discussed above, nine GWS studies [4452] but only one GWAS [53] in large study samples (n = 679–13524) support a role for loci at or near the ACE gene in contributing towards the variability of BP or the age at diagnosis of hypertension in either men or women. Moreover, the chromosomal region containing the ACE gene is the most consistent region across studies to show linkage with hypertension or BP, and the degree of linkage (LOD scores) is quantitatively similar to that observed for other chromosomal regions associated with hypertension or BP.

With respect to studies that show a lack of a relationship between the ACE gene and BP, one linkage study with a small sample size which employed a relatively insensitive statistical approach for a polygenic trait [37] opposes a role for the ACE gene in hypertension diagnosed on SBP, DBP, both or the presence of treatment. Hence there is no linkage evidence to exclude a role for the ACE gene in controlling DBP alone in men. Four cross-sectional studies with large study samples (n = 1245–10150) [38,4042] provide evidence to show that the ACE gene is not involved in controlling BP. However, in two studies [41,42], a relationship in men may have been possible if the study sample had been larger, and one study [40] did not explore the effects on DBP separately from SBP. Although two meta-analyses of both small and large studies do not support a role for the ACE gene in hypertension or BP [30,39], neither conclusively excluded a role for the ACE gene in controlling DBP in men.

With respect to the studies employing GWS or GWAS which have failed to show either linkage or association with chromosomal regions containing the ACE gene and either hypertension or BP, five GWS studies and the majority of GWAS refute a role for the ACE locus in BP control. However, the quality of BP assessments in studies that were in favour of a role for the ACE locus (Table 3) was overall better than that in studies which failed to support a role (Table 4). Moreover the failure of some GWS studies and GWAS to support a role for the ACE gene in BP control or hypertension is not unexpected, given the potential for inadequate marker coverage on GeneChips, an inability to detect small phenotypic effects of loci when employing conservative statistics (Bonferroni corrections), and the lack of gender-specific analyses in some studies.

Thus, in men, we suggest that the available evidence indicates that the ACE gene contributes to DBP and that this effect may not be trivial; however, this effect may not occur in all populations. The lack of effect in many populations is entirely consistent with the inability of the many GWS studies to reproduce linkage between a variety of chromosomal regions and BP in different populations [4452,5458]. What could potentially explain a lack of effect of the ACE gene in different populations?

The ACE gene may have different levels of penetrance depending on circumstances

There should be no expectation that the ACE or any other gene candidate must contribute toward BP at all times and under all circumstances. This point is best illustrated by the similar BP values measured in mice with two or three copies as compared with one copy of the ACE gene, despite marked differences in ACE concentrations [64]. However, under conditions of AngI (angiotensin I) infusion, differences in BP responses were observed [64]. Thus intrinsic homoeostatic control mechanisms can maintain constant BP levels, despite marked changes in ACE concentrations. To further support this notion, although the ACE 4556(C/T)2/3 genotype is strongly associated with plasma ACE concentrations in humans, in the same individuals this does not translate into increases in circulating AngII (angiotensin II) or aldosterone concentrations [29]. The obvious question therefore is under what conditions could we expect to observe an ACE gene effect on BP?

Genotype–phenotype and genotype–environment interactions

Interactions between genotype and environmental factors or phenotypic traits are characteristic of a polygenic trait. A good example is salt-sensitive hypertension, where a dramatic increase in BP may occur in some individuals in response to a salt load, whereas in salt-insensitive individuals, who presumably lack the susceptibility gene(s), BP is maintained in response to a salt load. Is their evidence that the ACE gene interacts with environmental or other phenotypic factors to influence BP?

Probably the best evidence for an interaction is in the studies demonstrating a gender-specific effect of the ACE gene on BP in humans [3234] and in genetically manipulated mice [31]. In this regard, the consistency of the relationship between ACE gene variations and BP in males only across these studies provides confidence that this interaction is real. Although, the mechanisms of the interactive effect of male gender and the ACE gene on BP are as yet unclear, and hence warrant further investigation, it has been suggested that an interaction between the Y chromosome and a locus that maps close to the ACE gene has an impact on BP response to salt-loading in SHR (spontaneously hypertensive rats) [65].

However, there are other potential interactions that need to be considered. In a study with 1875 persons, the ACE gene I/D variant has been shown to interact with body size to influence body size effects on BP [66]. Furthermore, in 71 [67] and in 61 [68] hypertensive subjects, the ACE gene has been shown to determine the extent to which salt intake increases BP with the I allele associated with a greater BP response to a salt load. Moreover, in 469 [69] and 304 [70] hypertensive subjects the ACE gene determined the extent to which age influences PP, SBP and DBP. Thus the question arises as to whether ACE genotyping could predict age-induced hypertension? Lastly, the influence of the ACE gene I/D polymorphism on BP has been shown to occur in smokers, but not non-smokers [71] and, hence, the effect of the gene could depend on smoking.

Although these are early studies [6671] and substantiation of these data is therefore required in much larger study samples and in different study groups, with laboratory-based data to support a mechanism of the interaction, these findings suggest that environmental (salt) or phenotypic (gender, body size and age) factors may determine the penetrance of the ACE gene effects on BP. In this regard, we believe that future studies on the ACE gene should consider more thoroughly establishing these interactive effects.

Genotype–genotype interactions

Interactions between the ACE and other candidate genes may also influence the penetrance of the ACE gene in mediating a BP effect. Indeed, in a study of 920 twins, a variant of the ACE gene was modestly and independently associated with BP but, in combination with an AGT gene variant, the impact on BP was markedly enhanced [72]. Moreover, in a follow-up study of 9.1 years (median period) in 678 participants, although the ACE genotype was associated with the incidence of hypertension, this effect was only observed to occur in those participants carrying either a functional variant of the ADD1 (α-adducin) gene or a variant of the CYPB11B2 (aldosterone synthase) gene [35]. As α-adducin and aldosterone affect renal tubular salt handling, this interaction may be likened to the interaction that is well known to occur between the RAS and renal salt handling, best illustrated by the value of combining ACEIs and diuretic agents to control BP. Thus it is possible that the ACE gene effects on BP are likely to be observed only in populations that carry a sufficiently high frequency of other gene variants, such as those within the AGT, ADD1 and CYP11B2 genes. Again, further work is required to replicate these findings in independent population samples with large study sizes.

The ACE gene effect on BP may depend on haplotypes within the locus

As the causal variant within the ACE gene has not been established, the question of whether the I/D variant is sufficient to establish a relationship between the gene and BP arises. More recently, the relationship between haplotypes of combinations of variants within the ACE gene and hypertension status was studied [73]. Using a sensitive method of analysis (the transmission disequilibrium test, which assesses the alleles transmitted from parents to offspring), haplotypes were linked to hypertension status in 1158 Nigerians, 546 Jamaicans and 1080 African-Americans, with the haplotypes transmitted in excess to hypertensive subjects differing in the three samples [73]. Although that study raises the question as to why different haplotypes produced these effects in different groups, clearly future studies should not restrict analysis to the ACE gene I/D variant, but consider haplotype analysis.

THE AGT GENE

Rationale for considering a role for the AGT gene in BP control

In line with evidence that plasma AGT concentrations track in families with an increased BP [74], in 1992 Jeunemaitre et al. [75] showed a relationship between a T→C nucleotide substitution at position 704 in exon 2 of the AGT gene and plasma AGT concentrations in two independent samples. This nucleotide substitution translates into a Met→Thr amino acid change at position 235 of the AGT protein (M235T polymorphism). A number of subsequent studies provided evidence to indicate that variations within the AGT gene are indeed associated with plasma AGT concentrations. In combined segregation and linkage analysis, the AGT gene has been shown to account for approx. 5% of the variance of plasma AGT concentrations [76]. Furthermore, a meta-analysis of seven studies with a total of 1085 people supports a role for the AGT gene in controlling plasma AGT concentrations, with the TT homozygotes of the M235T variant having plasma AGT concentrations approx. 11% higher than MM homozygotes (P<0.00001) [77].

Although unlikely to be functional itself, the M235T variant is in linkage disequilibrium with potentially functional variants within the AGT gene, including a number within the promoter region that could influence the expression of the AGT gene. In this regard, a G→A substitution at position −6 of the AGT gene is associated with increased basal AGT transcription rates [78]. In addition, an A→C substitution at position −20 of the AGT gene determines whether a major late transcription factor, rather than the oestrogen receptor (oestrogen is well known to determine AGT expression), binds to the promoter [79] and the variant accounts for approx. 10% of the variability of plasma AGT concentrations [80]. Moreover, a G→A substitution at position −217 of the AGT gene is also associated with increased basal AGT transcription rates [81]. Although there is no direct evidence for an effect on AGT gene transcription, a C→T substitution at position −532 of the AGT gene, which is located within a consensus sequence to the transcription factor AP-2 (activator protein-2), is strongly associated with plasma AGT concentrations [29].

Is human AGT involved in BP control? There are indeed reports of highly significant correlations between plasma AGT concentrations and BP [82]. However, there are no studies that have evaluated BP effects produced by targeting AGT in humans. Is there direct evidence to show that the AGT gene can control BP? In this regard, transgenic mice carrying the rat AGT gene develop hypertension [83], and inactivating or duplicating the AGT gene in mice results in marked decreases or increases in BP respectively [84].

Evidence for and against a role for the AGT gene in human BP control

Tables 5 and 6 summarize the characteristics of the major candidate gene studies that have evaluated the relationship between the AGT gene and human hypertension or BP that fulfil many of the criteria listed in points 1–6 described above. Table 5 shows the characteristics of the major studies showing linkage or an association with BP or hypertension [40,53,75,8592], whereas Table 6 shows the characteristics of the major studies providing evidence against a role for the AGT gene [5,93100]. Tables 3 and 4 summarize the characteristics of large GWS studies and GWAS which either show a relationship or which failed to show a relationship between sites at or near the AGT locus and BP or hypertension [4463]. It should be apparent that, as with the ACE gene, there are presently studies with considerable sample sizes that either support [40,44,50,52,53,75,8592] or refute [5,4549,51,5463,93100] a role for the AGT gene in controlling BP.

Table 5
Characteristics of major studies showing a relationship between the AGT gene and BP or hypertension

Details of points 1–6 are described in the text [1, n > 1000; 2, associations that make biological sense (NA, not applicable for GWS or GWAS); 3, ethnically matched case-control studies (NA, not applicable, as not a case-control study); 4, context-dependent analysis; 5, high-quality BP data (−, no details of BP measurements given); and 6, haplotype analysis]. Con., conventional; HT, hypertension.

Reference AGT gene variant Sample size Study design Population(s) sampled Phenotype assessed Effect 
Jeunemaitre et al. [75Tandem repeat 379 sib-pairs Linkage analysis Caucasians HT Linkage for HT (P<0.02)  ✓ NA ✓ ✓  
Caulfield et al. [85Tandem repeat 63 multiplex families Linkage analysis Caucasians HT Linkage for HT (P<0.001)  ✓ NA  ✓  
Caulfield et al. [86Tandem repeat 63 sib-pairs and extended families Linkage analysis African-Caribbeans HT Linkage for HT (P=0.001)  ✓ NA    
Baker et al. [91C→T(−532) M235T 1425 Family-based association and linkage Caucasians; 19% receiving treatment 24-h BP PP (P<0.0001) ✓ ✓ NA  ✓ ✓ 
Sethi et al. [87M235T T174M 9100 Cross-sectional Caucasians HT OR for HT in women with risk alleles = 1.50 (P<0.0001) ✓ ✓ ✓ ✓  ✓ 
Matsubara et al. [92T+31C 1245 Cross-sectional Japanese; approx. 30–40% receiving treatment Home BP PP in elderly (P=0.0018) ✓ ✓ ✓ ✓   
Castellano et al. [40M235T 2461 Cross-sectional Caucasians 75% hypertensive HT OR for HT=1.35 (P=0.003) ✓ ✓ ✓  ✓ ✓ 
Levy et al. [53rs2478518 2155 Family-based association Caucasians approx. 12–16% estimated to be receiving treatment Con. BP GEE association for DBP: P=0.021, and SBP: P=0.003 ✓ NA NA  ✓  
Staessen et al. [88M235T 13760 (32 studies) Meta-analysis (case-control) Caucasians HT OR for HT in TT compared with MM = 1.31 (P<0.001) ✓ ✓ ✓ ✓ −  
Kunz et al. [89M235T 5493 (12 studies) Meta-analysis (case-control) Caucasians HT OR for HT = 1.20 (P<0.0001) ✓ ✓   −  
Kato et al. [90M235T 2349 (six studies) Meta-analysis (case-control) Japanese HT OR for HT = 1.22 ✓ ✓ ✓  −  
Sethi et al. [77M235T T174M 18704 (22 studies) Meta-analysis (case-control) Caucasians HT OR for HT = 1.19 (P<0.0001) ✓ ✓   −  
Reference AGT gene variant Sample size Study design Population(s) sampled Phenotype assessed Effect 
Jeunemaitre et al. [75Tandem repeat 379 sib-pairs Linkage analysis Caucasians HT Linkage for HT (P<0.02)  ✓ NA ✓ ✓  
Caulfield et al. [85Tandem repeat 63 multiplex families Linkage analysis Caucasians HT Linkage for HT (P<0.001)  ✓ NA  ✓  
Caulfield et al. [86Tandem repeat 63 sib-pairs and extended families Linkage analysis African-Caribbeans HT Linkage for HT (P=0.001)  ✓ NA    
Baker et al. [91C→T(−532) M235T 1425 Family-based association and linkage Caucasians; 19% receiving treatment 24-h BP PP (P<0.0001) ✓ ✓ NA  ✓ ✓ 
Sethi et al. [87M235T T174M 9100 Cross-sectional Caucasians HT OR for HT in women with risk alleles = 1.50 (P<0.0001) ✓ ✓ ✓ ✓  ✓ 
Matsubara et al. [92T+31C 1245 Cross-sectional Japanese; approx. 30–40% receiving treatment Home BP PP in elderly (P=0.0018) ✓ ✓ ✓ ✓   
Castellano et al. [40M235T 2461 Cross-sectional Caucasians 75% hypertensive HT OR for HT=1.35 (P=0.003) ✓ ✓ ✓  ✓ ✓ 
Levy et al. [53rs2478518 2155 Family-based association Caucasians approx. 12–16% estimated to be receiving treatment Con. BP GEE association for DBP: P=0.021, and SBP: P=0.003 ✓ NA NA  ✓  
Staessen et al. [88M235T 13760 (32 studies) Meta-analysis (case-control) Caucasians HT OR for HT in TT compared with MM = 1.31 (P<0.001) ✓ ✓ ✓ ✓ −  
Kunz et al. [89M235T 5493 (12 studies) Meta-analysis (case-control) Caucasians HT OR for HT = 1.20 (P<0.0001) ✓ ✓   −  
Kato et al. [90M235T 2349 (six studies) Meta-analysis (case-control) Japanese HT OR for HT = 1.22 ✓ ✓ ✓  −  
Sethi et al. [77M235T T174M 18704 (22 studies) Meta-analysis (case-control) Caucasians HT OR for HT = 1.19 (P<0.0001) ✓ ✓   −  
Table 6
Characteristics of major studies that have failed to show a relationship between the AGT gene and BP or hypertension

Details of points 1,3–6 are described in the text [1, n>1000; 2, associations that make biological sense (NA, not applicable for GWS or GWAS); 3, ethnically matched case-control studies (NA, not applicable, as not a case-control study); 4, context-dependent analysis; 5, high-quality BP data; and 6, haplotype analysis]. Con., conventional; HT, hypertension.

Reference AGT gene variant Sample size Study design Population(s) sampled Phenotype assessed Effect 
Brand et al. [93Dinucleotide repeats 630 sib-pairs Linkage analysis Caucasians HT No linkage ✓ ✓ NA ✓   
Niu et al. [94Dinucleotide repeats 310 sib-pairs Linkage analysis Chinese HT No linkage  ✓ NA  ✓  
Niu et al. [95Dinucleotide repeats M235T T174M 310 sib-pairs Linkage analysis Chinese HT No linkage  ✓ NA  ✓  
Niu et al. [96M235T T174M 315 nuclear families Family-based association Chinese HT No association  ✓ NA  ✓  
Wang et al. [97Dinucleotide repeats 104 sib-ships Linkage analysis Caucasians HT No linkage  ✓ NA  ✓ ✓ 
Van Rijn et al. [5M235T 1006 Family-based study Genetically isolated Dutch; approx. 22–29% receiving treatment Con. BP No relationship with BP; heritability = 24–40% ✓ ✓ NA    
Province et al. [98G→A(−6) 4322 Pooled sib-pairs, sibships and extended families Caucasians; approx. 50% receiving treatment Con. BP No relationship with BP ✓ ✓ NA  ✓  
Larson et al. [99G→A(−6) 904 Cross-sectional African-American HT No relationship with HT  ✓ ✓  ✓  
Tiago et al. [100M235T A→C(−20) 1103 Case-control African ancestry HT diagnosed with 24-h BP No relationship with HT for either variant ✓ ✓ ✓ ✓ ✓  
Reference AGT gene variant Sample size Study design Population(s) sampled Phenotype assessed Effect 
Brand et al. [93Dinucleotide repeats 630 sib-pairs Linkage analysis Caucasians HT No linkage ✓ ✓ NA ✓   
Niu et al. [94Dinucleotide repeats 310 sib-pairs Linkage analysis Chinese HT No linkage  ✓ NA  ✓  
Niu et al. [95Dinucleotide repeats M235T T174M 310 sib-pairs Linkage analysis Chinese HT No linkage  ✓ NA  ✓  
Niu et al. [96M235T T174M 315 nuclear families Family-based association Chinese HT No association  ✓ NA  ✓  
Wang et al. [97Dinucleotide repeats 104 sib-ships Linkage analysis Caucasians HT No linkage  ✓ NA  ✓ ✓ 
Van Rijn et al. [5M235T 1006 Family-based study Genetically isolated Dutch; approx. 22–29% receiving treatment Con. BP No relationship with BP; heritability = 24–40% ✓ ✓ NA    
Province et al. [98G→A(−6) 4322 Pooled sib-pairs, sibships and extended families Caucasians; approx. 50% receiving treatment Con. BP No relationship with BP ✓ ✓ NA  ✓  
Larson et al. [99G→A(−6) 904 Cross-sectional African-American HT No relationship with HT  ✓ ✓  ✓  
Tiago et al. [100M235T A→C(−20) 1103 Case-control African ancestry HT diagnosed with 24-h BP No relationship with HT for either variant ✓ ✓ ✓ ✓ ✓  

Linkage analysis and family-based association analysis

Presently, the linkage and family-based association data are equally strong both for and against a role for the AGT gene in contributing toward BP. There are presently four studies that show linkage of the AGT gene with hypertension [75,85,86,91] (Table 5) and five studies that have failed to show linkage or family-based associations [9397] (Table 6). A wide range of sample sizes have been employed in the studies that show linkage [75,85,86,91] (Table 5) and those that do not [9397] (Table 6). Importantly, one of the studies that failed to show linkage [93] (Table 6) had a considerable sample size (n = 350 families and 630 affected sibling pairs); however, the method of analysis employed [93] is sensitive to allele frequency estimations when the parental genotypes are not known. Nevertheless, in that study [93], the same analytical methods were used to attempt to show linkage between the AGT gene and hypertension as those employed in most of the studies demonstrating linkage [75,85,86]. Moreover, using more sensitive analytical techniques which do not rely on precise specifications of the genetic models, in 335 hypertensive subjects from 315 nuclear families, a second group failed to show excess transmission of AGT gene variants to hypertensive Chinese subjects [94,96].

Cross-sectional and other association studies

As with the linkage data, cross-sectional and association data are equally strong both for and against a role for the AGT gene in contributing toward BP. As indicated in Table 5, a role for the AGT gene in hypertension is supported by cross-sectional population data obtained in 9100 randomly selected individuals (this association was in women only) [87] and in 2461 participants sampled from the general population in the GENIPER study [40]. A role for the AGT gene in BP control is supported by an association with PP determined from ambulatory BP measurements in 1425 individuals from 248 families each with one proband [91], and home BP measurements in 1245 individuals randomly selected from the general population [92] (Table 5). A striking characteristic of these studies is that they used different AGT gene markers to show these effects (Table 5) (T→M at amino acid position 174, C→T substitution at nucleotide position +521 [87], M235T [40], T+31C [92] and C→T substitution at nucleotide position −532 [91] within the AGT gene). Although Framingham data in 2155 participants have been cited as showing an association between AGT genotype and BP using the general estimations equation (Table 5) [53], this analysis was part of a much larger study intended to generate rather than test hypotheses and, hence, the outcomes were not corrected for multiple genotyping.

In contrast with the major studies showing positive associations, there are also key studies which have failed to show a relationship between the AGT gene and BP. In 4322 people of the NHLBI (National Heart Lung and Blood Institute) Family Blood Pressure Program (which pooled sib-pairs, sib-ships and extended families) [98], and in 904 randomly selected African-Americans [99], no relationship between G→A (−6) polymorphism and hypertension was observed (Table 6). Furthermore, in 1006 participants of a genetically isolated Dutch population sample, no relationship between the M235T variant and BP was observed, despite showing strong heritability estimates for the BP values obtained (Table 6) [5]. In a case-control study in 1103 participants of African ancestry living in Soweto, South Africa (where admixture is unlikely to confound), where the presence of hypertension was diagnosed using ambulatory BP monitoring, our own group have failed to show a relationship between either the M235T or the A→C (−20) variants of the AGT gene and hypertension (Table 6) [100]. Furthermore, in a large case-control study in 1358 participants, the homozygous TT genotype of the AGT M235T variant was even protective against hypertension [43] (not shown in Table 6).

Meta-analyses

Three meta-analyses performed on a number of small and large case-control studies, with substantial total sample sizes (n = 5493–18704), support a role for the AGT gene in contributing toward hypertension [77,8890]. These meta-analyses nevertheless warn of a potential publication bias.

Incidence studies

There are presently no studies that have achieved statistical power that have reported on an association between the AGT gene and the incidence of hypertension.

Genome-wide studies

Three GWS studies [44,50,52] and one GWAS [53] support linkage or an association between loci at or near the AGT locus and BP or age at diagnosis of hypertension, whereas eleven GWS studies [4549,51,5458] and five GWAS [5963] failed to show linkage or associations with the AGT loci. Hence the majority of genome-wide studies are against linkage and association between the AGT locus and BP or hypertension.

Summary

On the basis of the analysis of the major studies shown in Tables 3–6 and discussed above, there is some evidence of linkage of the AGT gene with hypertension, BP or PP [44,50,52,75,85,86,91], strong evidence of an association of the AGT gene with hypertension in a cross-sectional study which was multivariate-adjusted [87], positive evidence of associations with hypertension in meta-analyses [77,8890], and some evidence in GWS studies [44,50,52] and a GWAS [53] that supports a role for the AGT gene in BP control. However, there is also strong evidence in linkage analysis [4549,51,9396], cross-sectional studies [5,98,99], large case-control studies [43,100], GWS studies [4549,51] and GWAS [5458] that opposes a role for the AGT gene in BP control. Nevertheless, as underlined previously, the outcomes of GWS studies and GWAS should be taken in context, given the potential for inadequate marker coverage on GeneChips and an inability to detect small phenotypic effects of loci when using conservative statistics (Bonferroni corrections). Importantly, as also highlighted previously, the lack of effect in many populations is entirely consistent with the inability of the GWS studies to reproduce linkage between a variety of chromosomal regions and BP in different populations [4452,5458]. In this regard, should we expect all studies on the AGT gene to show a role for the gene in BP control?

The AGT gene may have different levels of penetrance depending on circumstances

As indicated previously, there should be no expectation that any gene candidate must contribute towards BP at all times and under all circumstances. Intrinsic homoeostatic control mechanisms may maintain constant BP levels, despite major physiological changes that tend to increase or decrease BP. To support this notion with respect to the AGT gene, although the C→T(−532) variant of the AGT gene is strongly associated with plasma AGT concentrations, this does not translate into increases in circulating AngII or aldosterone concentrations [29]. As with the ACE gene, therefore, the important question that arises is under what conditions could we expect the AGT gene to influence BP?

Genotype–phenotype and genotype–environment interactions

Is there evidence that the AGT gene interacts with environmental or other phenotypic factors to determine its penetrance? One possibility is an interaction with gender. Indeed, in a large (n = 9100) population-based study supporting a role for the AGT gene in hypertension, a relationship between the AGT gene and BP was observed in women only [87]. This gender-specific effect is consistent with the well-described effect of oestrogen on AGT expression. However, no other studies have explored a gender-specific effect and, thus, further studies are warranted to determine whether this genotype–gender interaction indeed exists.

There are other potential interactions that need to be considered. Although our group has failed to show a relationship between the AGT gene and hypertension, we were able to show a marked effect of the A→C(−20) variant of the AGT gene on the impact of body size on 24-h SBP in 521 untreated hypertensive subjects off medication [100]. This interaction is premised on the fact that adipose tissue is also a strong source of circulating AGT concentrations. These data are supported by a trend for a greater decrease in BP (−2.4 compared with +0.3 mmHg; P=0.05) in response to weight reduction in the Trials of Hypertension Prevention in people with the AA compared with the GG genotype of the G→A(−6) variant of the AGT gene [101]. Moreover, these data are also supported by the interaction between obesity and the AGT gene to determine renal vascular responses to AngII infusions [102]. The potential clinical use of obesity–AGT gene interactions could be profound considering the increasing prevalence of obesity worldwide, but replication in independent samples is still required.

An additional important interaction between the AGT gene and environmental effects is also suggested by data from the Trials of Hypertension Prevention study. Indeed, in a 3-year follow-up of 1509 people with DBP values of 83–89 mmHg, those subjects homozygous for the A allele of the G→A(−6) variant of the AGT gene developed a greater response to a reduced salt intake than in those individuals homozygous for the G allele (−2.2 compared with +1.1 mmHg; P=0.01) [101]. Considering that the overall SBP/DBP response to approx. 77 mmol/l salt restriction was −4.8/−2.5 mmHg, the genotype effect is indeed striking [101].

If these genotype–phenotype and genotype–environmental interactive effects are proved to be significant in future studies, the effect of the AGT gene on BP is likely to depend on circumstances (gender, salt intake or body size). In this regard, as with the ACE gene, we believe that future studies on the AGT gene should consider more thoroughly establishing these interactive effects, by replicating these data in much larger samples and providing convincing laboratory-based mechanisms.

Genotype–genotype interactions

As discussed above, interactions between the ACE and AGT genes may influence their penetrance. In this regard, in 920 twins, although a variant of the AGT gene showed only modest independent effects on BP, in combination with an ACE gene variant, the impact on BP was markedly enhanced [72].

The AGT gene effect on BP may depend on haplotypes within the locus

As the causal variant within the AGT gene has not been established, there should be no expectation that an analysis of the relationship between individual variants and BP are sufficient to establish a relationship between the gene and BP. Indeed, in one study, although individual AGT variants showed little relationship with plasma AGT concentrations, haplotypes accounted for approx. 7% of the variance [103]. With respect to BP effects of haplotypes, two separate groups have shown relationships between AGT gene haplotypes and either 24-h BP in 212 untreated hypertensive subjects [104], or hypertension in 788 people in a case-control study design [105]. In these studies [104,105], although haplotypes were associated with BP, individual gene variants were not. These studies [104,105] clearly require replication in larger population samples.

SUMMARY AND CONCLUSIONS

In summary, there are major studies demonstrating a role for both the ACE and AGT genes in hypertension and BP control and the effect size is not trivial. These studies have generally fulfilled the criteria that experts have recommended previously [1013], particularly with respect to the use of large sample sizes, replicating data in independent samples, using family-based and population-based designs, employing BP as a continuous trait in the analysis and thus enabling DBP and SBP to be considered separately, including multivariate adjustments in the analysis, and using informative genetic markers. These effects may be gender-specific in that the ACE gene may produce effects in men, whereas the AGT gene may produce effects in women. However, there is also strong evidence that opposes a role for specific variants of the ACE and AGT genes in either hypertension or BP control which have similarly fulfilled the criteria that experts have recommended previously [1013]. How do we view these contrasting outcomes?

As long as we accept that we are dealing with a polygenic trait, we believe that the impact of specific ACE and AGT gene variants on BP should never be expected to show effects in all samples. Interactions between genotype and phenotypes other than BP (gender, age, body size, salt intake and smoking) may determine BP changes. These interactions need to be established in larger studies which should also fulfil the criteria that experts have recommended [1013]. Interactions between genotypes in different loci (such as the AGT and ACE genes together, or the ACE, ADD1 and CYP11B2 genes together) need to be explored further. In this regard, some meritorious studies have been produced, but further work is required to replicate these findings in large study samples. Lastly, the concept of haplotype analysis and its importance in increasing the sensitivity of genotype–BP relationships is only beginning to emerge. As pointed out by the authors of one study [72], different haplotypes within a single gene may be required to show genotype–BP relationships. It is only by providing strong evidence for interactions and the correct haplotypes that should be employed that ACE and AGT genotyping will ever become a clinical reality.

FUNDING

The authors' work is supported by the Medical Research Council of South Africa, the National Research Foundation of South Africa, the Circulatory Disorders Research Trust, the Hypertension Society of South Africa, and the University Research Council of the University of the Witwatersrand.

Abbreviations

     
  • ACE

    angiotensin-converting enzyme

  •  
  • ACEI

    ACE inhibitor

  •  
  • AGT

    angiotensinogen

  •  
  • AngII

    angiotensin II

  •  
  • BP

    blood pressure

  •  
  • D

    deletion

  •  
  • DBP

    diastolic BP

  •  
  • GWAS

    genome-wide association studies

  •  
  • GWS

    genome-wide scan

  •  
  • I

    insertion

  •  
  • LOD

    logarithm of the odds

  •  
  • OR

    odds ratio

  •  
  • PP

    pulse pressure

  •  
  • RAS

    renin–angiotensin system

  •  
  • SBP

    systolic BP

References

References
1
Mancia
G.
de Backer
G.
Dominiczak
A.
Cifkova
R.
Germano
G.
Grassi
G.
Heagerty
A. M.
Kjeldsen
S. E.
Laurent
S.
Narkiewitcz
K.
, et al. 
2007 Guidelines for the Management of Arterial Hypertension: the Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC)
J. Hypertens.
2007
, vol. 
6
 (pg. 
1105
-
1187
)
2
Hertz
R. P.
Unger
A. N.
Cornell
J. A.
Saunders
E.
Racial disparities in hypertension prevalence, awareness and management
Arch. Intern. Med.
2005
, vol. 
165
 (pg. 
2098
-
2104
)
3
Natarajan
S.
Santa Ana
E. J.
Liao
Y.
Lipsitz
S. R.
McGee
D. L.
Effect of treatment and adherence on ethnic differences in blood pressure control among adults with hypertension
Ann. Epidemiol.
2009
, vol. 
19
 (pg. 
172
-
179
)
4
Steyn
K.
Gaziano
T. A.
Bradshaw
D.
Laubscher
R.
Fourie
J.
Hypertension in South African adults: results from the Demographic and Health Survey, 1998
J. Hypertens.
2001
, vol. 
19
 (pg. 
1717
-
1725
)
5
van Rijn
M. J.
Schut
A. F.
Aulchenko
Y. S.
Deinum
J.
Sayed-Tabatabaei
F. A.
Yazdanpanah
M.
Isaacs
A.
Axenovich
T. I.
Zorkoltseva
I. V.
Zillikens
M. C.
, et al. 
Heritability of blood pressure traits and the genetic contribution to blood pressure variance explained by four blood pressure-related genes
J. Hypertens.
2007
, vol. 
25
 (pg. 
565
-
570
)
6
Luft
F. C.
Twins in cardiovascular genetic research
Hypertension
2001
, vol. 
37
 (pg. 
350
-
356
)
7
Knuiman
M. W.
Divitini
M. L.
Welborn
T. A.
Bartholomew
H. C.
Familial correlations, cohabitation effects, and heritability for cardiovascular risk factors
Ann. Epidemiol.
1996
, vol. 
6
 (pg. 
1007
-
1013
)
8
Vinck
W. J.
Fagard
R. H.
Loos
R.
Vlietinck
R.
The impact of genetic and environmental influences on blood pressure variance across age-groups
J. Hypertens.
2001
, vol. 
19
 (pg. 
1007
-
1013
)
9
Linden
A.
Gartner's 2002 Hype Cycle for Emerging Technologies
2002
 
10
Anonymous
Freely associating
Nat. Genet.
1999
, vol. 
22
 (pg. 
1
-
2
)
11
Corvol
P.
Persu
A.
Gimenez-Roqueplo
A-P.
Jeunemaitre
X. J.
Seven lessons from two candidate genes in human essential hypertension
Hypertension
1999
, vol. 
33
 (pg. 
1324
-
1331
)
12
Sharma
A. M.
Jeunemaitre
X.
The future of genetic association studies in hypertension: improving the signal to noise ratio
J. Hypertens.
2000
, vol. 
18
 (pg. 
811
-
814
)
13
Gambaro
G.
Anglani
F.
D'Angelo
A.
Association studies of genetic polymorphisms and complex disease
Lancet
2000
, vol. 
355
 (pg. 
308
-
311
)
13a
Arnett
D. K.
Claas
S. A.
Glasser
S. P.
Pharmacogenetics of hypertensive treatment
Vasc. Pharmacol.
2006
, vol. 
44
 (pg. 
107
-
118
)
14
Farahani
P.
Dolovich
L.
Levine
M.
Exploring design-related bias in clinical studies on receptor genetic polymorphism of hypertension
J. Clin. Epidemiol.
2007
, vol. 
60
 (pg. 
1
-
7
)
15
Carden
L. R.
Palmer
L. J.
Population stratification and spurious allelic association
Lancet
2003
, vol. 
361
 (pg. 
598
-
604
)
16
Khoury
M. J.
Adams
M. J.
Flanders
W. D.
An epidemiologic approach to ecogenetics
Am. J. Hum. Genet.
1988
, vol. 
42
 (pg. 
89
-
95
)
17
Kuznetsova
T.
Staessen
J. A.
Brand
E.
Cwynar
M.
Stolarz
K.
Thijs
L.
Tikhonoff
V.
Wojciechowska
W.
Babeanu
S.
Brand-Hermann
S-M.
, et al. 
Sodium excretion as a modulator of genetic associations with cardiovascular phenotypes in the European Project on Genes in Hypertension
J. Hypertens.
2006
, vol. 
24
 (pg. 
235
-
242
)
18
Hottenga
J. J.
Boomsma
D. I.
Kupper
N
Posthuma
D.
Snieder
H.
Willemsen
G.
de Geus
E. J.
Heritability and stability of resting blood pressure
Twin Res. Hum. Genet.
2005
, vol. 
8
 (pg. 
499
-
508
)
19
Fava
C.
Burri
P.
Almgren
P.
Groop
L.
Lennart Huthen
U.
Melander
O.
Heritability of ambulatory and office blood pressure phenotypes in Swedish families
J. Hypertens.
2004
, vol. 
22
 (pg. 
1717
-
1721
)
20
Bochud
M.
Bovet
P.
Elston
R. C.
Paccaud
F.
Falconnet
C.
Maillard
M.
Shamlaye
C.
Burnier
M.
High heritability of ambulatory blood pressure in families of East African descent
Hypertension
2005
, vol. 
45
 (pg. 
445
-
450
)
21
Hansen
T. W.
Kikuya
M.
Thijs
L.
BjorklundBodegard
K.
Kuznetsova
T.
Ohkubo
T.
Richart
T.
Torp-Pedersen
C.
Lind
L.
Jeppesen
J.
, et al. 
Prognostic superiority of daytime ambulatory over conventional blood pressure in four populations: a meta-analysis of 7030 individuals
J. Hypertens.
2007
, vol. 
25
 (pg. 
1554
-
1564
)
22
Boggia
J.
Li
Y.
Thijs
L.
Hansen
T. W.
Kikuya
M.
Bjorklund-Bodegard
K.
Richart
T.
Ohkubo
T.
Kuznetsova
T.
Torp-Pedersen
C.
, et al. 
Prognostic accuracy of day versus night ambulatory blood pressure: a cohort study
Lancet
2007
, vol. 
370
 (pg. 
1210
-
1229
)
23
Rigat
B.
Hubert
C.
Alhenc-Gelas
F.
Cambien
F.
Corvol
P.
Soubrier
F.
An insertion/deletion polymorphism of the angiotensin I-converting enzyme gene accounting for half of the variance of serum enzyme levels
J. Clin. Invest.
1990
, vol. 
86
 (pg. 
1343
-
1346
)
24
Tiret
L.
Rigat
B.
Visvikis
S.
Breda
C.
Corvol
P.
Cambien
F.
Soubrier
F.
Evidence from combined segregation and linkage analysis that a variant of the angiotensin I-converting enzyme (ACE) gene controls plasma ACE levels
Am. J. Hum. Genet.
1992
, vol. 
51
 (pg. 
197
-
205
)
25
McKenzie
C. A.
Julier
C.
Forrester
T.
McFarlaneAnderson
N.
Keavney
B.
Lathrop
G. M.
Ratcliffe
P. J.
Farrall
M.
Segregation and linkage analysis of serum angiotensin-converting enzyme levels; evidence for two quantitative trait loci
Am. J. Hum. Genet.
1995
, vol. 
57
 (pg. 
1426
-
1435
)
26
Villard
E.
Tiret
L.
Visvikis
S.
Rakotova
R.
Cambien
F.
Soubrier
F.
Identification of new polymorphisms of the angiotensin I-converting enzyme (ACE) gene and study of their relationship to plasma ACE levels by two-QTL segregation-linkage analysis
Am. J. Hum. Genet.
1996
, vol. 
58
 (pg. 
1268
-
1278
)
27
Farrall
M.
Keavney
B.
McKenzie
C.
Delepine
M.
Mastuda
F.
Lathrop
G. M.
Fine mapping of an ancestral recombination breakpoint in DCP1
Nat. Genet.
1999
, vol. 
23
 (pg. 
270
-
271
)
28
Zhu
X.
McKenzie
C. A.
Forrester
T.
Nickerson
D. A.
Broekel
U.
Schunkert
H.
Doering
A.
Jacob
H. J.
Cooper
R. S.
Riedre
M. J.
Localisation of a small genomic region associated with elevated ACE
Am. J. Hum. Genet.
2000
, vol. 
67
 (pg. 
1144
-
1153
)
29
Paillard
F.
Chansel
D.
Brand
E.
Benetos
A.
Thomas
F.
Czekalski
S.
Ardaillou
R.
Soubrier
F.
Genotype–phenotype relationships for the renin–angiotensin–aldosterone system in a normal population
Hypertension
1999
, vol. 
34
 (pg. 
423
-
429
)
30
Agerholm-Larsen
B.
Nordestgaard
B. G.
Tybjaerg-Hansen
A.
ACE gene polymorphism in cardiovascular disease: meta-analyses of small and large studies in whites
Arterioscler. Thromb. Vasc. Biol.
2000
, vol. 
20
 (pg. 
484
-
492
)
31
Krege
J. H.
John
S. W.
Langenbach
L. L.
Hodgin
J. B.
Hagaman
J. R.
Bachman
E. S.
Jennette
J. C.
O'Brien
D. A.
Smithies
O.
Male-female differences in fertility and blood pressure in ACE-deficient mice
Nature.
1995
, vol. 
375
 (pg. 
146
-
148
)
32
Fornage
M.
Amos
C. I.
Kardia
S.
Sing
C. F.
Turner
S. T.
Boerwinkle
E.
Variation in the region of the angiotensin-converting enzyme gene influences interindividual differences in blood pressure levels in young white males
Circulation.
1998
, vol. 
97
 (pg. 
1773
-
1779
)
33
O'Donnell
C. J.
Lindpainter
K.
Larson
M. G.
Rao
V. S.
Ordovas
J. M.
Schaefer
E. J.
Myers
R. H.
Levy
D.
Evidence for association and genetic linkage of the angiotensin-converting enzyme locus with hypertension and blood pressure in men but not women in the Framingham Heart Study
Circulation
1998
, vol. 
97
 (pg. 
1766
-
1772
)
34
Higaki
J.
Baba
S.
Katsuya
T.
Sato
N.
Ishikawa
K.
Mannami
T.
Ogata
J.
Ogihara
T.
Deletion allele of the angiotensin-converting enzyme gene increases risk of essential hypertension in men: the Suita Study
Circulation
2000
, vol. 
101
 (pg. 
2060
-
2065
)
35
Staessen
J. A.
Wang
J. G.
Brand
E.
Barlassina
C.
Birkenhager
W. H.
Hermann
S.-M.
Fagard
R.
Tizzani
L.
Bianchi
G.
Effects of three candidate genes on prevalence and incidence of hypertension in a Caucasian population
J. Hypertens.
2001
, vol. 
19
 (pg. 
1349
-
1358
)
36
Di Pasquale
P.
Cannizzaro
S.
Paterna
S.
Does angiotensin-converting enzyme gene polymorphism affect blood pressure?. Findings after 6 years of follow-up in healthy subjects
Eur. J. Heart Failure
2004
, vol. 
6
 (pg. 
611
-
616
)
37
Jeunemaitre
X.
Lifton
R.
Hunt
S. C.
Williams
R. R.
Lalouel
J-M.
Absence of linkage between the angiotensin converting enzyme locus and human essential hypertension
Nat. Genet.
1992
, vol. 
1
 (pg. 
72
-
75
)
38
Agerholm-Larsen
B.
Nordestgaard
B. G.
Steffensen
R.
Sorensen
T. A.
Jensen
G.
Tybjaerg-Hansen
A.
ACE gene polymorphism: ischaemic heart disease and longevity in 10,150 individuals: a case referent and retrospective cohort study based on the Copenhagen City Heart Study
Circulation
1997
, vol. 
95
 (pg. 
2358
-
2367
)
39
Staessen
J. A.
Wang
J. G.
Ginocchio
G.
Petrov
V.
Saavedra
A. P.
Soubrier
F.
Vlietinck
R.
Fagard
R.
The deletion/insertion polymorphism of the converting enzyme gene and cardiovascular-renal risk
J. Hypertens.
1997
, vol. 
15
 (pg. 
1579
-
1592
)
40
Castellano
M.
Glorioso
N.
Cusi
D.
Sarzani
R.
Fabris
B.
Opoocher
G.
Zoccali
C.
Golin
R.
Veglio
F.
Volpe
M.
, et al. 
Genetic polymorphism of the renin-angiotensin-aldosterone system and arterial hypertension in the Italian population. The GENIPER Project
J. Hypertens.
2003
, vol. 
21
 (pg. 
1853
-
1860
)
41
Matsubara
M.
Suzuki
M.
Fujiwara
T.
Kikuya
M.
Metoki
H.
Michmata
M.
Araki
T.
Kazama
I.
Satoh
T.
Hashimoto
J.
, et al. 
Angiotensin-converting enzyme I/D polymorphism and hypertension: The Ohasama Study
J. Hypertens.
2002
, vol. 
20
 (pg. 
1049
-
1051
)
42
Zaman
M. M.
Yoshiike
N.
Date
C.
Yokoyama
T.
Matsumura
Y.
Ikemoto
S.
Tanaka
H.
Angiotensin converting enzyme genetic polymorphism is not associated with hypertension in a cross-sectional sample of a Japanese population: The Shibata Study
J. Hypertens.
2001
, vol. 
19
 (pg. 
47
-
53
)
43
Mondry
A.
Loh
M.
Liu
P.
Zhu
A-L.
Nagel
M.
Polymorphisms of the insertion/deletion ACE and M235T AGT genes and hypertension: surprising new findings and meta-analysis
BMC Nephrol.
2005
, vol. 
6
 pg. 
1
 
44
Bielinski
S. J.
Lynch
A. I.
Miller
M. B.
Weder
A.
Cooper
R.
Oberman
A.
Chen
Y-D. I.
Turner
S. T.
Fornage
M.
Province
M.
Arnett
D. K.
Genome-wide linkage analysis for loci affecting pulse pressure: the family blood pressure program
Hypertension
2005
, vol. 
46
 (pg. 
1286
-
1293
)
45
de Lange
M.
Spector
T. D.
Andrew
T.
Genome-wide scan for blood pressure suggests linkage to chromosome 11, and replication of loci on 16, 17 and 22
Hypertension
2004
, vol. 
44
 (pg. 
872
-
877
)
46
Gu
C. C.
Hunt
S. C.
Kardia
S.
Turner
S. T.
Chakravarti
A.
Schork
N.
Olshen
R.
Curb
D.
Jaquish
C.
Boerwinkle
E.
Rao
D. C.
An investigation of the genome-wide associations of hypertension with microsatellite markers in the family blood pressure program (FBPP)
Hum. Genet.
2007
, vol. 
121
 (pg. 
577
-
590
)
47
Hottenga
J-J.
Whitfield
J. B.
Posthuma
D.
Willemsen
G.
de Geus
E. J. C.
Martin
N. G.
Boomsma
D. I.
Genome-wide scan for blood pressure in Australian and Dutch subjects suggests a linkage at 5p, 14q, and 17p
Hypertension
2007
, vol. 
49
 (pg. 
832
-
838
)
48
Jacobs
K. B.
Gray-McGuire
C.
Cartier
K. C.
Elston
R. C.
Genome-wide linkage scan for genes affecting longitudinal trends in systolic blood pressure
BMC Genet.
2003
, vol. 
4
 
Suppl. 1
(pg. 
S82
-
S86
)
49
Levy
D.
DeStefano
A. L.
Larson
M. G.
O'Donnell
C. J.
Lifton
R. P.
Gavras
H.
Cupples
L. A.
Myers
R. H.
Evidence for a gene influencing blood pressure on chromosome 17. Genome scan linkage results for longitudinal blood pressure phenotypes in subjects from the Framingham Heart Study
Hypertension
2000
, vol. 
36
 (pg. 
477
-
483
)
50
Rice
T.
Rankinen
T.
Province
M. A.
Chagnon
Y. C.
Perusse
L.
Borecki
I. B.
Bouchard
C.
Rao
D. C.
Genome-wide linkage analysis of systolic and diastolic blood pressure: the Quebec family study
Circulation
2000
, vol. 
102
 (pg. 
1956
-
1963
)
51
Wang
R-Y.
Chung
C-M.
Fann
C. S. J.
Yang
H-C.
Chen
J-W.
Jong
Y-S.
Jou
Y-S.
Lo
H-M.
Ho
F-M.
Kang
C-S.
, et al. 
Genome-wide scan for quantitative ACE activity in Taiwan young-onset hypertension study
Hum. Hered.
2008
, vol. 
65
 (pg. 
85
-
90
)
52
Wilk
J. B.
Djousse
L.
Arnett
D. K.
Hunt
S. C.
Province
M. A.
Heiss
G.
Myers
R. H.
Genome-wide linkage analyses for age at diagnosis of hypertension and early-onset hypertension in the HyperGEN study
Am. J. Hypertens.
2004
, vol. 
17
 (pg. 
839
-
844
)
53
Levy
D.
Larson
M. G.
Benjamin
E. J.
Newton-Cheh
C.
Wang
T. J.
Hwang
S-J.
Vasan
R. S.
Mitchell
G. F.
Framingham Heart Study 100K project: genome-wide associations for blood pressure and arterial stiffness
BMC Genet.
2007
, vol. 
8
 
Suppl. 1
(pg. 
S3
-
S13
)
54
Adeyemo
A.
Luke
A.
Wu
X.
Cooper
R. S.
Kan
D.
Omotade
O.
Zhu
X.
Genetic effects on blood pressure localized to chromosomes 6 and 7
J. Hypertens.
2005
, vol. 
23
 (pg. 
1367
-
1373
)
55
Caulfield
M.
Munroe
P.
Pembroke
J.
Samani
N.
Dominiczak
A.
Brown
M.
Benjamin
N.
Webster
J.
Ratcliffe
P.
O'Shea
S.
, et al. 
Genome-wide mapping of human loci for essential hypertension
Lancet
2003
, vol. 
361
 (pg. 
2118
-
2123
)
56
DeStefano
A. L.
Larson
M. G.
Mitchell
G. F.
Benjamin
E. J.
Vasan
R. S.
Li
J.
Corey
D.
Levy
D.
Genome-wide scan for pulse pressure in the National Heart, Lung and Blood Institute's Framingham Heart Study
Hypertension
2004
, vol. 
44
 (pg. 
152
-
155
)
57
Morrison
A. C.
Brown
A.
Kardia
S. L. R.
Turner
S. T.
Boerwinkle
E.
Evaluating the context-dependent effect of family history of stroke in a genome scan for hypertension
Stroke
2003
, vol. 
34
 (pg. 
1170
-
1175
)
58
Morrison
A. C.
Cooper
R.
Hunt
S.
Lewis
C. E.
Luke
A.
Mosley
T. H.
Boerwinkle
E.
Genome scan for hypertension in nonobese African Americans
Am. J. Hypertens.
2004
, vol. 
17
 (pg. 
834
-
838
)
59
Adeyemo
A.
Gerry
N.
Chen
G.
Herbert
A.
Doumatey
A.
Huang
H.
Zhou
J.
Lashley
K.
Chen
Y.
Christman
M.
Rotimi
C.
A genome-wide association study of hypertension and blood pressure in African Americans
PLoS Genet.
2009
, vol. 
5
 pg. 
e1000564
 
60
Ehret
G. B.
O'Connor
A. A.
Weder
A.
Cooper
R. S.
Chakravarti
A.
Follow-up of a major linkage peak on chromosome 1 reveals suggestive QTLs associated with essential hypertension: GenNet study
Eur. J. Hum. Genet.
2009
, vol. 
17
 (pg. 
1650
-
1657
)
61
Org
E.
Eyheramendy
S.
Juhanson
P.
Gieger
C.
Lichtner
P.
Klopp
N.
Veldre
G.
Doring
A.
Viigimaa
M.
Sober
S.
, et al. 
Genome-wide scan identifies CDH13 as a novel susceptibility locus contributing to blood pressure determination in two European populations
Hum. Mol. Genet.
2009
, vol. 
18
 (pg. 
2288
-
2296
)
62
Sober
S.
Org
E.
Kepp
K.
Juhanson
P.
Eyheramendy
S.
Gieger
C.
Lichtner
P.
Klopp
N.
Veldre
G.
Viigimaa
M.
, et al. 
Targeting 160 candidate genes for blood pressure regulation with genome-wide genotyping array
PLoS ONE 4
2009
pg. 
e6034
 
63
The Wellcome Trust, Case Control Consortium
Genome-wide association study of 14000 cases of seven common diseases and 3000 shared controls
Nature
2007
, vol. 
447
 (pg. 
661
-
678
)
64
Krege
J. H.
Kim
H-S.
Moyer
J. S.
Jennette
J. C.
Peng
L.
Hiller
S. K.
Smithies
O.
Angiotensin-converting enzyme gene mutations, blood pressures, and cardiovascular homeostasis
Hypertension
1997
, vol. 
29
 (pg. 
150
-
157
)
65
Kreutz
R.
Stock
P.
Struk
B.
Linpainter
K.
The Y chromosome: epistatic and ecogenetic interactions in genetic hypertension
Hypertension
1996
, vol. 
28
 (pg. 
895
-
897
)
66
Turner
S. T.
Boerwinkle
E.
Sing
C. F.
Context-dependent associations of the ACE I/D polymorphism with blood pressure
Hypertension
1999
, vol. 
34
 (pg. 
773
-
778
)
67
Poch
E.
Gonzales
D.
Giner
V.
Bragulat
E.
Coca
A.
de la Sierra
A.
Molecular basis of salt-sensitivity in human hypertension
Hypertension
2001
, vol. 
38
 (pg. 
1204
-
1209
)
68
Hiraga
H
Oshima
T.
Watanabe
M.
Ishida
M.
Ishida
T.
Shingu
T.
Kamber
M.
Matsuura
H.
Kajiyama
G.
Angiotensin I-converting enzyme gene polymorphism and salt-sensitivity in essential hypertension
Hypertension
1996
, vol. 
27
 (pg. 
569
-
572
)
69
Safar
M. E.
Lajemi
M.
Rudnichi
A.
Asmar
R.
Benetos
A.
Angiotensin I-converting enzyme D/I gene polymorphism and age-related changes in pulse pressure in subjects with hypertension
Arterioscler. Thromb. Vasc. Biol.
2004
, vol. 
24
 (pg. 
782
-
786
)
70
Rudnichi
A.
Safar
M. E.
Lajemi
M.
Benetos
A.
Gene polymorphisms of the renin-angiotensin system and age-related changes in systolic and diastolic blood pressure in subjects with hypertension
Am. J. Hypertens.
2004
, vol. 
17
 (pg. 
321
-
327
)
71
Schut
A. F.
Sayed-Tabatabaei
F. A.
Witteman
J. C.
Bertoli Avella
A. M.
Vergeer
J. M.
Pols
H. A. P.
Hofman
A.
Deinum
J.
van Duijn
C. M.
Smoking-dependent effects of the angiotensin-converting enzyme gene insertion/deletion polymorphism on blood pressure
J. Hypertens.
2004
, vol. 
22
 (pg. 
313
-
319
)
72
Ge
D.
Zhu
H.
Huang
Y.
Treiber
F. A.
Harshfield
G. A.
Snieder
H.
Dong
Multilocus analyses of renin-angiotensin-aldosterone system gene variants on blood pressure at rest and during behavioural stress in young normotensive subjects
Hypertension
2007
, vol. 
49
 (pg. 
107
-
112
)
73
Bouzekri
N.
Zhu
X.
Jiang
Y.
McKenzie
C. A.
Luke
A.
Forrester
T.
Adeyemo
A.
Kan
D.
Farrall
M.
Anderson
S.
, et al. 
Angiotensin I-converting enzyme polymorphisms, ACE level and blood pressure among Nigerians, Jamaicans and African-Americans
Eur. J. Hum. Genet.
2004
, vol. 
12
 (pg. 
460
-
468
)
74
Watt
G. C.
Harrap
S. B.
Foy
C. J. W.
Holton
D. W.
Edwards
H. V.
Davidson
H. R.
Connor
J. M.
Lever
A. F.
Fraser
R.
Abnormalities of glucocorticoid metabolism and the renin-angiotensin system: a four corners approach to the identification of genetic determinants of blood pressure
J. Hypertens.
1992
, vol. 
10
 (pg. 
473
-
482
)
75
Jeunemaitre
X.
Soubrier
F.
Kotelevtsev
Y. V.
Lifton
R. P.
Williams
C. S.
Charru
A.
Hunt
S. C.
Hopkins
P. N.
Williams
R. R.
Lalouel
J-M.
Molecular basis of human hypertension: role of angiotensinogen
Cell
1992
, vol. 
71
 (pg. 
169
-
180
)
76
Brand
E.
Chatelain
N.
Pailllard
F.
Tiret
L.
Visvikis
S.
Lathrop
M.
Soubrier
F.
Demenais
F.
Detection of putative functional angiotensinogen (AGT) gene variants controlling plasma AGT levels by combined segregation-linkage analysis
Eur. J. Hum. Genet.
2002
, vol. 
10
 (pg. 
715
-
723
)
77
Sethi
A. A.
Nordestgaardt
B. G.
Tybjaerg-Hansen
A.
Angiotensinogen gene polymorphism, plasma angiotensinogen, and risk of hypertension and ischaemic heart disease: a meta-analysis
Arterioscler. Thromb. Vasc. Biol.
2003
, vol. 
23
 (pg. 
1269
-
1275
)
78
Inoue
I.
Nakajima
T.
Williams
C. S.
Quackenbush
J.
Puryear
R.
Powers
M.
Cheng
T.
Ludwig
E. H.
Sharma
A. M.
Hata
A.
, et al. 
A nucleotide substitution in the promoters of human angiotensinogen is associated with essential hypertension and affects basal transcription
J. Clin. Invest.
1997
, vol. 
99
 (pg. 
1786
-
1797
)
79
Zhao
Y. Y.
Zhou
J.
Narayanan
C. S.
Cui
Y.
Kumar
A.
Role of C/A polymorphism at −20 on the expression of human angiotensinogen gene
Hypertension
1999
, vol. 
33
 (pg. 
108
-
115
)
80
Ishigami
T.
Umewara
S.
Tamura
K.
Hibi
K.
Nyui
N.
Kihara
M.
Yabana
M.
Watanabe
Y.
Sumida
Y.
Nagahara
T.
, et al. 
Essential hypertension and 5′ upstream core promoter region of human angiotensinogen gene
Hypertension
1997
, vol. 
30
 (pg. 
1325
-
1330
)
81
Jain
S.
Tang
X.
Narayanan
C. S.
Agarwal
Y.
Peterson
S. M.
Brown
C. D.
Ott
J.
Kumar
A.
Angiotensinogen gene polymorphism at −217 affects basal promoter activity and is associated with hypertension in African-Americans
J. Biol. Chem.
2002
, vol. 
277
 (pg. 
36889
-
36896
)
82
Walker
W. G.
Whelton
P. K.
Saito
H.
Russel
R. P.
Hermann
J.
Relations between blood pressure and renin, renin substrate, angiotensin II, aldosterone and urinary sodium and potassium in 574 ambulatory subjects
Hypertension
1979
, vol. 
1
 (pg. 
287
-
291
)
83
Kimura
S.
Mullins
J. J.
Bunnemann
B.
Metzger
R.
Hilgenfeldt
U.
Zimmerman
F.
Jacob
H.
Fuxe
K.
Ganten
D.
Kaling
M.
High blood pressure in transgenic mice carrying the rat angiotensinogen gene
EMBO J.
1992
, vol. 
11
 (pg. 
821
-
827
)
84
Kim
H-S.
Krege
J. H.
Kluchman
K. D.
Hagaman
J. R.
Hodgin
J. B.
Best
C. F.
Jennette
J. C.
Coffman
T. M.
Maeda
N.
Smithies
O.
Genetic control of blood pressure and the angiotensinogen locus
Proc. Natl. Acad. Sci. U.S.A.
1995
, vol. 
92
 (pg. 
2735
-
2739
)
85
Caulfield
M.
Lavender
P.
Farrall
M.
Munroe
P.
Lawson
M.
Turner
P.
Clark
A. J. L.
Linkage of the angiotensinogen gene to essential hypertension
N. Engl. J. Med.
1994
, vol. 
33
 (pg. 
1629
-
1633
)
86
Caulfield
M.
Lavender
P.
Newell-Price
J.
Farrall
M.
Kamdar
S.
Daniel
H.
Lawson
M.
De Frietas
P.
Fogarty
P.
Clark
A. J.
Linkage of the angiotensinogen gene locus to human essential hypertension in African Caribbeans
J. Clin. Invest.
1995
, vol. 
96
 (pg. 
687
-
692
)
87
Sethi
A. A.
Nordestgaardt
B. G.
Agerholm-Larsen
B.
Frandsen
E.
Jensen
G.
Tybjaerg-Hansen
A.
Angiotensinogen polymorphisms and elevated blood pressure in the general population: the Copenhagen Heart Study
Hypertension
2001
, vol. 
37
 (pg. 
875
-
881
)
88
Staessen
J. A.
Kuznetsova
T.
Wang
J. G.
Emelianov
D.
Vlietinck
R.
Fagard
R.
M235T angiotensinogen gene polymorphism and cardiovascular renal risk
J. Hypertens.
1999
, vol. 
17
 (pg. 
9
-
17
)
89
Kunz
R.
Kreutz
R.
Beige
J.
Distler
A.
Sharma
A. M.
Association between the angiotensinogen 235T variant and essential hypertension in whites: a systematic review and methodological appraisal
Hypertension
1997
, vol. 
30
 (pg. 
1331
-
1337
)
90
Kato
N.
Sugiyama
T.
Morita
H.
Kurihara
H.
Yamori
Y.
Yazaki
Y.
Angiotensinogen gene and essential hypertension in the Japanese: extensive association study and meta-analysis on six reported studies
J. Hypertens.
1999
, vol. 
17
 (pg. 
757
-
763
)
91
Baker
M.
Rahman
T.
Hall
D.
Avery
P. J.
Mayosi
B. M.
Connell
J. M.
Farrall
M.
Watkins
H.
Keavney
B.
The C−532T polymorphism of the angiotensinogen gene is associated with pulse pressure: a possible explanation for heterogeneity in genetic association studies of AGT and hypertension
Int. J. Epidemiol.
2007
, vol. 
36
 (pg. 
1356
-
1362
)
92
Matsubara
M.
Metoki
H.
Katsuya
T.
Kikuya
M.
Suzuki
M.
Michimata
M.
Araki
T.
Hozawa
A.
Tsuji
I.
Ogihara
T.
Imai
Y.
T+31C polymorphism (M235T) of the angiotensinogen gene and home blood pressure in the Japanese general population: the Ohasama Study
Hypertens. Res.
2003
, vol. 
26
 (pg. 
47
-
52
)
93
Brand
E.
Chatelain
N.
Keavney
B.
Caulfield
M.
Citterio
L.
Connell
J.
Grobbee
D.
Schmidt
S.
Schunkert
H.
Schuster
H.
Sharma
A.
Soubrier
F.
Evaluation of the angiotensinogen locus in human essential hypertension: a European study
Hypertension
1998
, vol. 
31
 (pg. 
725
-
729
)
94
Niu
T.
Xu
X.
Cordell
H. J.
Rogus
J.
Zhou
Y.
Fang
Z.
Lindpainter
K.
Linkage analysis of candidate genes and gene-gene interactions in Chinese hypertensive sib-pairs
Hypertension
1999
, vol. 
33
 (pg. 
1332
-
1337
)
95
Niu
T.
Xu
X.
Rogus
J.
Zhou
Y.
Chen
C.
Yang
Z.
Schmitz
C.
Zhao
J.
Rao
V. S
Lindpainter K. Angiotensinogen gene and hypertension in Chinese
J. Clin. Invest.
1998
, vol. 
101
 (pg. 
188
-
194
)
96
Niu
T.
Yang
J.
Wang
B.
Chen
W.
Wang
Z.
Laird
N.
Wei
E.
Fang
Z.
Lindpainter
K.
Rogus
J. J.
Xu
X.
Angiotensinogen gene polymorphisms M235T/T174M. No excess transmission to hypertensive Chinese
Hypertension
1999
, vol. 
33
 (pg. 
698
-
702
)
97
Wang
W. Y. S.
Glenn
C. L.
Zhang
W.
Benjafield
A. V.
Nyholt
D. R.
Morris
B. J.
Exclusion of angiotensinogen gene in molecular basis of human hypertension: sibpair linkage and association analyses in Australian Anglo-Caucasians
Am. J. Med.
1999
, vol. 
87
 (pg. 
53
-
60
)
98
Province
M. A.
Boerwinkle
E.
Chakravarti
A.
Cooper
R.
Fornage
M.
Leppert
M.
Risch
N.
Ranade
K.
Lack of association of the angiotensinogen −6 polymorphism with blood pressure levels in the comprehensive NHLBI Family Blood Pressure Program
J. Hypertens.
2000
, vol. 
18
 (pg. 
867
-
876
)
99
Larson
N.
Hutchinson
R.
Boerwinkle
E.
Lack of association of 3 functional gene variants with hypertension in African Americans
Hypertension
2000
, vol. 
35
 (pg. 
1297
-
1300
)
100
Tiago
A. D.
Samani
N. J.
Candy
G. P.
Brooksbank
R.
Libhaber
E.
Sareli
P.
Woodiwiss
A. J.
Norton
G. R.
Angiotensinogen gene promoter region variant modifies body-size-ambulatory blood pressure relations in hypertension
Circulation.
2002
, vol. 
106
 (pg. 
1483
-
1487
)
101
Hunt
S. C.
Cook
N. R.
Oberman
A.
Cutler
J. A.
Hennekens
C. H.
Allender
P. S.
Walker
W. G.
Whelton
P. K.
Williams
R. R.
Angiotensinogen genotype, sodium reduction, weight loss, and prevention of hypertension: Trials of Hypertension Prevention, Phase II
Hypertension
1998
, vol. 
32
 (pg. 
393
-
401
)
102
Hopkins
P. N.
Lifton
R. P.
Hollenberg
N. K.
Jeunemaitre
X.
Hallouin
M-C.
Skuppin
J.
Williams
C. S.
Dluhy
R. G.
Lalouel
J-M.
Williams
R. R.
Williams
G. H.
Blunted renal vascular response to angiotensin II is associated with a common variant of the angiotensinogen gene and obesity
J. Hypertens.
1996
, vol. 
14
 (pg. 
199
-
207
)
103
Wu
X.
Luke
A.
Rieder
M.
Lee
K.
Toth
E. J.
Nickerson
D.
Zhu
X.
Kan
D.
Cooper
R. S.
An association study of angiotensinogen polymorphism with serum level and hypertension in an African American population
J. Hypertens.
2003
, vol. 
21
 (pg. 
1847
-
1852
)
104
Brand-Herrmann
S. M.
Kopke
K.
Reichenberger
F.
Schmidt-Petersen
K.
Reineke
T.
Paul
M.
Zidek
W.
Brand
E.
Angiotensinogen promoter haplotypes are associated with blood pressure in untreated hypertensives
J. Hypertens.
2004
, vol. 
22
 (pg. 
1289
-
1297
)
105
Wu
S. J.
Chiang
F. T.
Chen
W. J.
Liu
P. H.
Hus
K. L.
Hwang
J. J.
Lai
P. P.
Lin
J. L.
Tseng
C. D.
Tseng
Y. Z.
Three single-nucleotide polymorphisms of the angiotensinogen gene and susceptibility to hypertension: single locus genotype vs haplotype analysis
Physiol. Genomics
2004
, vol. 
17
 (pg. 
79
-
86
)