Renin-angiotensin system haplotypes and the risk of myocardial infarction and stroke in pharmacologically treated hypertensive patients

Familial Analysis of Epistatic and Sex-Dependent Association of Genes of the Renin-Angiotensin-Aldosterone System and Blood Pressure

BACKGROUND

Renin-angiotensin-aldosterone system genes have been inconsistently associated with blood pressure, possibly because of unrecognized influences of sex-dependent genetic effects or gene-gene interactions (epistasis).

METHODS AND RESULTS

We tested association of systolic blood pressure with single-nucleotide polymorphisms (SNPs) at renin (REN), angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin II type 1 receptor (AGTR1), and aldosterone synthase (CYP11B2), including sex-SNP or SNP-SNP interactions. Eighty-eight tagSNPs were tested in 2872 white individuals in 809 pedigrees from the Victorian Family Heart Study using variance components models. Three SNPs (rs8075924 and rs4277404 at ACE and rs12721297 at AGTR1) were individually associated with lower systolic blood pressure with significant (P<0.00076) effect sizes ≈1.7 to 2.5 mm Hg. Sex-specific associations were seen for 3 SNPs in men (rs2468523 and rs2478544 at AGT and rs11658531 at ACE) and 1 SNP in women (rs12451328 at ACE). SNP-SNP interaction was suggested (P<0.005) for 14 SNP pairs, none of which had shown individual association with systolic blood pressure. Four SNP pairs were at the same gene (2 for REN, 1 for AGT, and 1 for AGTR1). The SNP rs3097 at CYP11B2 was represented in 5 separate pairs.

CONCLUSIONS

SNPs at key renin-angiotensin-aldosterone system genes associate with systolic blood pressure individually in both sexes, individually in one sex only and only when combined with another SNP. Analyses that incorporate sex-dependent and epistatic effects could reconcile past inconsistencies and account for some of the missing heritability of blood pressure and are generally relevant to SNP association studies for any phenotype.

Reporting of Bayesian analysis in epidemiologic research should become more transparent

OBJECTIVES

The objective of this systematic review is to investigate the use of Bayesian data analysis in epidemiology in the past decade and particularly to evaluate the quality of research papers reporting the results of these analyses.

STUDY DESIGN AND SETTING

Complete volumes of five major epidemiological journals in the period 2005-2015 were searched via PubMed. In addition, we performed an extensive within-manuscript search using a specialized Java application. Details of reporting on Bayesian statistics were examined in the original research papers with primary Bayesian data analyses.

RESULTS

The number of studies in which Bayesian techniques were used for primary data analysis remains constant over the years. Though many authors presented thorough descriptions of the analyses they performed and the results they obtained, several reports presented incomplete method sections and even some incomplete result sections. Especially, information on the process of prior elicitation, specification, and evaluation was often lacking.

CONCLUSION

Though available guidance papers concerned with reporting of Bayesian analyses emphasize the importance of transparent prior specification, the results obtained in this systematic review show that these guidance papers are often not used. Additional efforts should be made to increase the awareness of the existence and importance of these checklists to overcome the controversy with respect to the use of Bayesian techniques. The reporting quality in epidemiological literature could be improved by updating existing guidelines on the reporting of frequentist analyses to address issues that are important for Bayesian data analyses.

Angiotensinogen-M235T as a risk factor for myocardial infarction in Asian populations: a genetic association study and a bioinformatics approach

Aim

To investigate if there is an association between M235T polymorphism of angiotensinogen gene and myocardial infarction (MI) risk and perform a meta-analysis and an in silico approach.

Methods

This case-control study included 340 participants (155 MI patients and 185 controls) examined at Kashan University of Medical Sciences (Kashan, Iran) between 2013 and 2015. Meta-analysis included 25 studies with 6334 MI patients and 6711 controls. Bioinformatics tools were applied to evaluate the impact of M235T polymorphism on angiotensinogen function and structure.

Results

Genetic association study revealed a significant association between TT genotype (odds ratio [OR] 2.08, 95% confidence interval [CI] 1.08-4.00, P = 0.029) and T allele (OR 1.45, 95% CI 1.06-1.99, P = 0.021) and MI risk. Meta-analysis also revealed a significant association between M235T polymorphism and MI risk in allelic (OR 1.55, 95% CI 1.10-2.18, P = 0.012) and recessive (OR 1.69, 95% CI 1.13-2.53, P = 0.010) models within Asian population. In silico-analysis revealed that M235T fundamentally changed the function of angiotensinogen (score 32; expected accuracy 66%).

Conclusions

Our study suggests that M235T polymorphism might be a helpful biomarker for screening of susceptible individuals for MI in Asian population.

Influence of angiotensin converting enzyme (ACE) gene rs4362 polymorphism on the progression of kidney failure in patients with autosomal dominant polycystic kidney disease (ADPKD)

Background & objectives:

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited systemic disorder, characterized by the fluid filled cysts in the kidneys leading to end stage renal failure in later years of life. Hypertension is one of the major factors independently contributing to the chronic kidney disease (CKD) progression. The renin-angiotensin aldosterone system (RAAS) genes have been extensively studied as hypertension candidate genes. The aim of the present study was to investigate the role of angiotensin converting enzyme tagging - single nucleotide polymorphisms (ACE tag-SNPs) in progression of CKD in patients with ADPKD.

Methods:

In the present study six ACE tagSNPs (angiotensin converting enzyme tag single nucleotide polymorphisms) and insertion/deletion (I/D) in 102 ADPKD patients and 106 control subjects were investigated. The tagSNPs were genotyped using FRET-based KASPar method and ACE ID by polymerase chain reaction (PCR) and electrophoresis. Genotypes and haplotypes were compared between ADPKD patients and controls. Univariate and multivariate logistic regression analyses were performed to assess the effect of genotypes and hypertension on CKD advancement. Mantel-Haenszel (M-H) stratified analysis was performed to study the relationship between different CKD stages and hypertension and their interaction.

Results:

All loci were polymorphic and except rs4293 SNP the remaining loci followed Hardy-Weinberg equilibrium. Distribution of ACE genotypes and haplotypes in controls and ADPKD patients was not significant. A significant linkage disequilibrium (LD) was observed between SNPs forming two LD blocks. The univariate analysis revealed that the age, hypertension, family history of diabetes and ACE rs4362 contributed to the advancement of CKD.

Interpretation & conclusions:

The results suggest that the ACE genotypes are effect modifiers of the relationship between hypertension and CKD advancement among the ADPKD patients.

Risk given by AGT polymorphisms in inducing susceptibility to essential hypertension among isolated populations from a remote region of China: A case-control study among the isolated populations

INTRODUCTION

Hypertension is a serious risk factor affecting up to 30% of the world's population with a heritability of more than 30-50%. The aim of this study was to investigate the contribution of the polymorphisms localized in the angiotensinogen (AGT) gene, a main component of the renin-angiotensin-aldosterone system, in inducing the susceptibility to essential hypertension (EH) among isolated populations (Yi and Hani minorities) with low prevalence rate from the remote region of Yunnan in China.

METHODS

A case-control association study was performed, and all subjects were genotyped for the seven single nucleotide polymorphisms localized in the AGT region by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Three polymorphisms, i.e. rs5046, rs5049, and rs2478544, were significantly associated with EH among the Hani minority. The associations, found in the Yi minority, did not reach a conclusive level of statistical significance. The polymorphisms of rs2478544 and rs5046 caused the transformations of exonic splicing enhancer sites and transcription factor binding sites, respectively, in the bioinformatic analyses. The haplotype-rs5046T, rs5049A, rs11568020G, rs3789679C, rs2478544C was susceptible for EH among the Hani minority.

CONCLUSION

Our findings suggested that the AGT polymorphisms have played a vital role in determining an individual's susceptibility to EH among the isolated population, which would be helpful for EH management in the remote mountainous region of Yunnan in China.

Evidence of heterogeneity by race/ethnicity in genetic determinants of QT interval

BACKGROUND

QT interval (QT) prolongation is an established risk factor for ventricular tachyarrhythmia and sudden cardiac death. Previous genome-wide association studies in populations of the European descent have identified multiple genetic loci that influence QT, but few have examined these loci in ethnically diverse populations.

METHODS

Here, we examine the direction, magnitude, and precision of effect sizes for 21 previously reported SNPs from 12 QT loci, in populations of European (n = 16,398), African (n = 5,437), American Indian (n = 5,032), Hispanic (n = 1,143), and Asian (n = 932) descent as part of the Population Architecture using Genomics and Epidemiology (PAGE) study. Estimates obtained from linear regression models stratified by race/ethnicity were combined using inverse-variance weighted meta-analysis. Heterogeneity was evaluated using Cochran's Q test.

RESULTS

Of 21 SNPs, 7 showed consistent direction of effect across all 5 populations, and an additional 9 had estimated effects that were consistent across 4 populations. Despite consistent direction of effect, 9 of 16 SNPs had evidence (P < 0.05) of heterogeneity by race/ethnicity. For these 9 SNPs, linkage disequilibrium plots often indicated substantial variation in linkage disequilibrium patterns among the various racial/ethnic groups, as well as possible allelic heterogeneity.

CONCLUSIONS

These results emphasize the importance of analyzing racial/ethnic groups separately in genetic studies. Furthermore, they underscore the possible utility of trans-ethnic studies to pinpoint underlying casual variants influencing heritable traits such as QT.

[Association of T174M polymorphism of the angiotensinogen gene with the higher risk of cerebral stroke in women]

AIM

To study the association of M235T (rs699) and T174M (rs4762) polymorphisms of the angiotensinogen (AGT) gene with the risk of cerebral stroke (CS) in the Russians of the Central Chernozem Region.

MATERIALS AND METHODS

A total of 638 DNA samples obtained from 353 patients with CS and 285 sex- and age-matched healthy individuals were examined. The polymorphisms were genotyped by polymerase chain reaction (T174M) and TaqMan allelic discrimination (M235T) assays.

RESULTS

Heterozygous AGT 174TM genotype carriers were found to be at a higher risk for CS (odd ratio (OR) = 1.52; 95% confidence interval (CI), 1.08-2.15; p = 0.02). A gender-stratified analysis showed that the mutant 174M allele (OR = 1.86; 95% CI, 1.14-3.03, p = 0.01) and variant 174TM and 174MM genotypes (OR = 1.86; 95% CI, 1.09-3.20; p = 0.02) were associated with the higher risk of cerebral stroke in women.

CONCLUSION

The association of AGT T174M polymorphism with the risk of CS was first found; but the higher risk of the disease in the carriers of variant alleles and genotypes was observed in the women only.

Non-iterative, regression-based estimation of haplotype associations with censored survival outcomes

The general availability of reliable and affordable genotyping technology has enabled genetic association studies to move beyond small case-control studies to large prospective studies. For prospective studies, genetic information can be integrated into the analysis via haplotypes, with focus on their association with a censored survival outcome. We develop non-iterative, regression-based methods to estimate associations between common haplotypes and a censored survival outcome in large cohort studies. Our non-iterative methods--weighted estimation and weighted haplotype combination--are both based on the Cox regression model, but differ in how the imputed haplotypes are integrated into the model. Our approaches enable haplotype imputation to be performed once as a simple data-processing step, and thus avoid implementation based on sophisticated algorithms that iterate between haplotype imputation and risk estimation. We show that non-iterative weighted estimation and weighted haplotype combination provide valid tests for genetic associations and reliable estimates of moderate associations between common haplotypes and a censored survival outcome, and are straightforward to implement in standard statistical software. We apply the methods to an analysis of HSPB7-CLCNKA haplotypes and risk of adverse outcomes in a prospective cohort study of outpatients with chronic heart failure.

Assessment of two missense polymorphisms (rs4762 and rs699) of the angiotensinogen gene and stroke

The renin-angiotensin system has an important role in the pathogenesis of stroke. We investigated whether two missense single nucleotide polymorphisms (SNPs; rs4762, Thr207Met, T207M; and rs699, Met268Thr, M268T) of angiotensinogen (AGT; serpin peptidase inhibitor, clade A, member 8) are associated with the development and clinical phenotypes of ischemic stroke (IS) and intracerebral hemorrhage (ICH). We analyzed 197 stroke patients (120 IS and 77 ICH) and 301 control subjects. The patients were classified into subgroups in accordance to the scores of the National Institutes of Health Stroke Survey (NIHSS, <6 and ≥6) and Modified Barthel Index (MBI, <60 and ≥60). Multiple logistic regression models were used to analyze the genotype and allele distributions of each SNP. One of the missense SNPs, rs4762 (T207M) was associated with the development of ICH (P=0.038 in log-additive model and P=0.021 in allele distributions). The T allele frequency of T207M was higher in the ICH group (16.2%) compared with the control group (9.6%). The TC haplotype frequency differed significantly between the ICH and control groups (P=0.014). With regard to clinical features, T207M correlated with the NIHSS scores of the ICH patients (P=0.039 in codominant1, P=0.015 in dominant, P=0.011 in overdominant and P=0.039 in log-additive models). However, the two missense SNPs, rs4762 and rs699, were not associated with IS and its clinical features, including NIHSS and MBI scores. These data suggest that a missense SNP (rs4762, T207M) of the AGT gene may be associated with the development of ICH and contribute to the neurological functional levels of ICH patients.

SNPs in microRNA binding sites in 3'-UTRs of RAAS genes influence arterial blood pressure and risk of myocardial infarction

BACKGROUND

We hypothesized that single nucleotide polymorphisms (SNPs) located in microRNA (miR) binding sites in genes of the renin angiotensin aldosterone system (RAAS) can influence blood pressure and risk of myocardial infarction.

METHODS

Using online databases dbSNP and TargetScan, we identified 10 SNPs in potential miR binding sites in eight RAAS-related genes, common in Caucasians. We genotyped a large case-control study on myocardial infarctions, the Study of Myocardial Infarctions LEiden (SMILE) for these 10 SNPs and found nine SNPs, in seven genes, to be prevalent. Functionality of each SNP in interfering with mRNA/miR binding was tested using a dual luciferase reporter gene system.

RESULTS

Of these nine SNPs, four SNPs, located in the arginine vasopressin 1A receptor (AVPR1A), bradykinin 2 receptor (BDKRB2), and thromboxane A2 receptor (TBXA2R) genes were associated with blood pressure. The rare allele of the AVPR1A SNP rs11174811, was associated with increased blood pressure whereas the rare alleles of the two linked BDKRB2 SNPs rs5225 and rs2069591 and of the TBXA2R SNP rs13306046 were associated with decreased blood pressure. Although not associated with blood pressure, the rare allele of the mineralocorticoid receptor (NR3C2) SNP rs5534, was associated with a twofold increased risk of myocardial infarction in men younger than 50 years. For all of these five SNPs, except rs2069591, we could demonstrate a reduction in miR-induced repression of gene expression.

CONCLUSIONS

Common SNPs in miR binding sites of RAAS-related genes can influence both blood pressure and risk of myocardial infarction. These results may imply an important role for SNPs in miR target sites in human disease.

Difference in angiotensinogen haplotype frequencies between chronic heart failure and advanced atherosclerosis patients - new prognostic factor?

Numerous association studies have been involved in studying the angiotensinogen (AGT) variants, AGT plasma levels and relations to cardiovascular diseases, such as hypertension, myocardial infarction, coronary heart disease. To investigate a role of AGT G(-6)A and M235T genetic variants for chronic heart failure (CHF) and advanced atherosclerosis (AA), a total of 240 patients with CHF and 200 patients with AA of the Czech origin were evaluated for the study. The study shows the role of polymorphism AGT G(-6)A in genetic background among advanced atherosclerosis patients and chronic heart failure patients (Pg=0.001). This difference was also observed in comparison of AA patients with subgroup of CHF with dilated cardiomyopathy (Pg=0.02; Pa=0.009), and ischemic heart disease (Pg=0.007). The greatest difference between triple-vessel disease and chronic heart failure groups was observed in frequency of GT haplotype (P<0.001) and GGMT associated genotype (P<0.001). Retrospectively, we found the same trend when the subgroups of CHF were compared to AA group (AA vs. IHD with CHF P<0.001; AA vs. DCM P<0.001). These results suggest AGT genetic variants as a risk factor for chronic heart failure compared to advanced atherosclerosis disease without heart failure, with a strong difference between IHD patients and chronic heart failure patients with ischemic heart disease, especially in haplotypes and associated genotypes.

Angiotensin receptor gene polymorphisms and 2-year change in hyperintense lesion volume in men

This longitudinal study examined the relationship between 2-year change in white matter hyperintense lesion (WML) volume and polymorphisms in genes coding for the angiotensin-II type 1 and type 2 receptors, AGTR1 A1166C and AGTR2 C3123A, respectively. 137 depressed and 94 non-depressed participants aged >or=60 years were enrolled. Standard clinical evaluations were performed on all participants and blood samples obtained for genotyping. 1.5-T MRI (magnetic resonance imaging) data were obtained at baseline and approximately 2 years later. These scans were processed using a semi-automated segmentation process, which allowed for the calculation of WML volume at each time point. Statistical models were tested for the relationship between change in WML volume and genotype, while also controlling for age, sex, diagnostic strata, baseline WML volume and comorbid cerebrovascular risk factors. In men, AGTR1 1166A allele homozygotes exhibited significantly less change in WML volume than 1166C carriers. We also found that men reporting hypertension (HTN) with the AGTR2 3123C allele exhibit less change in WML volume than hypertensive men with the 3123A allele, or men without HTN. There were no significant relationships between these polymorphisms and change in WML volume in women. No significant gene-gene or gene-depression interactions were observed. Our results parallel earlier observed gender differences of the relationship between other renin-angiotensin system polymorphisms and HTN. Further work is needed to determine whether these observed relationships are secondary to polymorphisms affecting response to antihypertensive medication, and whether antihypertensive medications can slow WML progression and lower the risk of morbidity associated with WMLs.

ACE (I/D) polymorphism and response to treatment in coronary artery disease: a comprehensive database and meta-analysis involving study quality evaluation

BACKGROUND

The role of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in modifying the response to treatment modalities in coronary artery disease is controversial.

METHODS

PubMed was searched and a database of 58 studies with detailed information regarding ACE I/D polymorphism and response to treatment in coronary artery disease was created. Eligible studies were synthesized using meta-analysis methods, including cumulative meta-analysis. Heterogeneity and study quality issues were explored.

RESULTS

Forty studies involved invasive treatments (coronary angioplasty or coronary artery by-pass grafting) and 18 used conservative treatment options (including anti-hypertensive drugs, lipid lowering therapy and cardiac rehabilitation procedures). Clinical outcomes were investigated by 11 studies, while 47 studies focused on surrogate endpoints. The most studied outcome was the restenosis following coronary angioplasty (34 studies). Heterogeneity among studies (p < 0.01) was revealed and the risk of restenosis following balloon angioplasty was significant under an additive model: the random effects odds ratio was 1.42 (95% confidence interval:1.07-1.91). Cumulative meta-analysis showed a trend of association as information accumulates. The results were affected by population origin and study quality criteria. The meta-analyses for the risk of restenosis following stent angioplasty or after angioplasty and treatment with angiotensin-converting enzyme inhibitors produced non-significant results. The allele contrast random effects odds ratios with the 95% confidence intervals were 1.04(0.92-1.16) and 1.10(0.81-1.48), respectively. Regarding the effect of ACE I/D polymorphism on the response to treatment for the rest outcomes (coronary events, endothelial dysfunction, left ventricular remodeling, progression/regression of atherosclerosis), individual studies showed significance; however, results were discrepant and inconsistent.

CONCLUSION

In view of available evidence, genetic testing of ACE I/D polymorphism prior to clinical decision making is not currently justified. The relation between ACE genetic variation and response to treatment in CAD remains an unresolved issue. The results of long-term and properly designed prospective studies hold the promise for pharmacogenetically tailored therapy in CAD.

Association between renin-angiotensin-aldosterone system genotypes and haplotypes and risk of ischemic stroke of atherosclerotic etiology

OBJECTIVE

The association of renin C-4063T and angiotensinogen (AGT) T174M, AGT M235T and AGT A-6G polymorphisms with ischemic stroke of atherosclerotic etiology was investigated in 329 Tunisian patients with stroke and 444 controls.

MATERIALS AND METHODS

Genotyping was performed using PCR-RFLP and the contributions of polymorphisms to the risk of stroke were analyzed using haplotype and multivariate regression analysis.

RESULTS

AGT 235T and AGT-6G allele and AGT 235T/T, AGT-6A/G and AGT-6G/G genotype frequencies were higher in patients. Linkage disequilibrium (LD) was noted for AGT174T with AGT235M and AGT(-6)A in patients, while AGT235M was in LD with AGT(-6)A in controls and AGT235T was in LD with AGT(-6)G in both groups. The AGT 174T/235T/-6A and AGT 174T/235M/-6G haplotypes were positively and negatively associated with stroke respectively. Multivariate regression analysis identified AGT 174T/235M/-6A, AGT 174T/235T/-6G, AGT 174T/235T/-6A and AGT 174M/235T/-6A haplotypes to be significantly associated with an increased risk of stroke.

CONCLUSIONS

Renin-angiotensin-aldosterone system polymorphisms influence the risk of atherosclerotic stroke in Tunisians.