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

Association study of WNK1 genetic variants and essential hypertension risk in the Northern Han Chinese in Beijing

Background: Essential hypertension (EH) is a complex disorder resulting from interaction of genetic and environmental factors. Lysine deficient protein kinase 1 (WNK1) plays a very important role in maintaining renal potassium, sodium and chlorine ions balance as well as the regulation of blood pressure, so the WNK1 gene is considered a key gene for EH. This study thus sought to evaluate possible genetic associations between the WNK1 genetic variants and EH risk in the Northern Han Chinese population in Beijing. Methods: This study included 476 hypertensive subjects and 491 normotensive subjects. A total of 12 tag SNVs of WNK1 gene were genotyped successfully by TaqMan assay. Comparisons of the genotypic and allelic frequency between cases and controls were made by using the chi-square test. Logistic regression analyses were performed under different genetic models, and haplotype analysis was also conducted. Results: A total of 12 SNVs were identified as the tag SNVs for WNK1 gene. Significant associations were observed between WNK1 gene rs7305099 variant and EH risk, and T allele influenced hypertension risk in a protective manner. After correcting for multiple testing using Bonferroni, the significance remained for the SNV of rs7305099 in three genetic models [allele comparison, p < 0.0002, OR = 0.627, 95%CI (0.491-0.801); homozygote comparison, p < 0.0003, OR = 0.278, 95%CI (0.140-0.552); additive model, p < 0.0003, OR = 0.279, 95%CI (0.140-0.553)]. In the haplotype analyses, we found that the haplotype A-A-A-C-G-G-G was significantly associated with increased risk for EH (p = 0.043, OR = 1.23). Conclusion: Our data suggested that the rs7305099 genetic variant and the haplotype A-A-A-C-G-G-G on WNK1 gene might be associated with the susceptibility of EH in the Northern Han Chinese population. These could provide evidences to the risk assessment, early prevention and individualized therapy of EH to some extent.

Hypertension Across a Woman's Life Cycle

PURPOSE OF REVIEW

We reviewed the effects of hypertension and the means to prevent and treat it across the spectrum of a woman's lifespan and identified gaps in sex-specific mechanisms contributing to hypertension in women that need to be addressed.

RECENT FINDINGS

Hypertension continues to be an important public health problem for women across all life stages from adolescence through pregnancy, menopause, and older age. There remain racial, ethnic, and socioeconomic differences in hypertension rates not only overall but also between the sexes. Blood pressure cutoffs during pregnancy have not been updated to reflect the 2017 ACC/AHA changes due to a lack of data. Additionally, the mechanisms behind hypertension development in menopause, including sex hormones and genetic factors, are not well understood. In the setting of increasing inactivity and obesity, along with an aging population, hypertension rates are increasing in women. Screening and management of hypertension throughout a women's lifespan are necessary to reduce the burden of cardiovascular disease, and further research to understand sex-specific hypertension mechanisms is needed.

Association of cytochromes P450 3A4*22 and 3A5*3 genotypes and polymorphism with response to simvastatin in hypercholesterolemia patients

Backgrounds

Inter-individual variability in response to statin was mainly due to genetic differences. This study aimed to investigate the association of CYP3A4*22 (rs35599367), CYP3A5*3 (rs776746) single nucleotide polymorphism (SNP) with response to simvastatin in hypercholesterolemia patients conducted at King Abdulaziz University hospital (KAUH) in Jeddah, Saudi Arabia.

Patients and methods

A total of 274 participants were registered in the current study. Hypercholesterolemic patients taking simvastatin 20 mg (n = 148) and control subjects (n = 126) were tested for rs35599367 and rs776746 genotypes using Custom Taqman ® Assay Probes. Response to simvastatin in these patients was assessed by determination of low density lipoprotein (LDL-C), total cholesterol (TC) and by measuring statin plasma levels using Liquid Chromatography-Mass Spectrometry (LC-MS).

Results

None of the participants carried a homozygous CYP3A4*22 mutant genotype, while 12 (4.4%) individuals had a heterozygous genotype and 262 (95.6%) had a wild homozygous genotype. The CYP3A5*3 allele was detected in the homozygous mutant form in 16 (5.8%) individuals, while 74 (27.0%) individuals carried the heterozygous genotype and 184 (67.2%) carried the wildtype homozygous genotype. Of the patient group, 15 (11%) were classified as intermediate metabolizers (IMs) and 133 (89%) as extensive metabolizers (EMs). Plasma simvastatin concentrations for the combined CYP3A4/5 genotypes were significantly (P<0.05) higher in the IMs group than in the EMs group. TC and plasma LDL-C levels were also significantly (P<0.05) higher in IMs than in EMs.

Conclusion

The present study showed associations between CYP3A4*22 (rs35599367) and CYP3A5*3 (rs776746) SNP combination genotypes with response to statins in hypercholesterolemia. Patients who had either a mutant homozygous allele for CYP3A5*3 or mutant homozygous and heterozygous alleles for CYP3A4*22 showed increased response to lower TC and LDL-C levels.

Dyslipidemia and the Prevalence of Hypertension: A Cross-Sectional Study Based on Chinese Adults Without Type 2 Diabetes Mellitus

Background

In clinical practice, it is frequently observed that patients with hypertension often coexist with dyslipidemia. However, studies on atherosclerotic indices and the prevalence of hypertension are still limited. The purpose of this study was to assess the relationship between atherosclerotic indices and the prevalence of hypertension in Chinese adults without type 2 diabetes mellitus.

Methods

In this paper, a cross-sectional study was conducted based on 117,056 adults in 11 Chinese cities (Shanghai, Beijing, Wuhan, Suzhou, Shenzhen, Changzhou, Nantong, Guangzhou, Hefei, Nanjing, and Chengdu) from 2010 to 2016. Besides, the raw data was obtained from the public database (www.Datadryad.org), while eight atherosclerosis indices namely the atherogenic coefficient (AC), Castelli's risk index I (CRI-I) and II (CRI-II), the atherogenic index of plasma (AIP), the cholesterol index, the lipoprotein combined index (LCI), non-high-density lipoprotein cholesterol (non-HDL-C) and triglycerides/high-density lipoprotein cholesterol (TG/HDL-C) were analyzed in this study. Apart from that, two groups of continuous variables were measured using the Mann-Whitney test, and categorical variables were analyzed using the Chi-square test. Differences between multiple groups of continuous variables were investigated using Kruskal-Wallis one-way analysis of variance (ANOVA) and Dunn's test. Furthermore, Spearman correlation analysis and multivariate logistic regression analyses were performed to assess the relationship between atherosclerotic indices and blood pressure levels, and the prevalence of hypertension, respectively. The results of multivariate logistic regression analyses were expressed as the odds ratio (OR) and their corresponding 95% confidence intervals (CIs). Moreover, the receiver operating characteristic (ROC) curve was depicted to further analyze the predictive value of the atherosclerotic indices on the prevalence of hypertension.

Results

The atherosclerosis indices were higher in the hypertensive population compared to those in the normotensive population. Meanwhile, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were linearly and positively correlated with atherosclerotic indices. In addition, multivariate logistic regression analysis showed that the cholesterol index and non-HDL-C were observed to be positively associated with the prevalence of hypertension (p for trend &lt; 0.05). Moreover, the prevalence of hypertension increased by 3.7% (OR: 1.037; 95% CI: 1.009-1.065; p = 0.009) and 6.1% (OR: 1.06; 95% CI: 1.033–1.091; p &lt; 0.001), respectively, as per 1-standard deviation (SD) increase in the cholesterol index and non-HDL-C. Beyond that, ROC analysis demonstrated that the cholesterol index and non-HDL-C have a good predictive value for the prevalence of hypertension in women, with under the ROC curve (AUC) of 0.659 and 0.684 and cut-off values of 47.94 and 134.34 mg/dl, accordingly.

Conclusions

In Chinese adults without type 2 diabetes mellitus, atherosclerotic indices were significantly higher in hypertensive populations compared with those in normotensive populations, regardless of hypertension levels. Meanwhile, SBP and DBP were linearly and positively related to atherosclerotic indices. Besides, the cholesterol index and non-HDL-C were independent risk factors for the prevalence of hypertension, and they could be adopted for effectively predicting the prevalence of hypertension in women.

A Review of Vascular Traits and Assessment Techniques, and Their Heritability

Various tools are available to assess atherosclerosis, arterial stiffening, and endothelial function. They offer utility in the assessment of hypertensive phenotypes, in cardiovascular risk prediction, and as surrogate endpoints in clinical trials. We explore the relative influence of participant genetics, with reference to large-scale genomic studies, population-based cohorts, and candidate gene studies. We find heritability estimates highest for carotid intima-media thickness (CIMT 35–65%), followed by pulse wave velocity as a measure of arterial stiffness (26–43%), and flow mediated dilatation as a surrogate for endothelial function (14–39%); data were lacking for peripheral artery tonometry. We furthermore examine genes and polymorphisms relevant to each technique. We conclude that CIMT and pulse wave velocity dominate the existing evidence base, with fewer published genomic linkages for measures of endothelial function. We finally make recommendations regarding planning and reporting of data relating to vascular assessment techniques, particularly when genomic data are also available, to facilitate integration of these tools into cardiovascular disease research.

How measurements affected by medication use are reported and handled in observational research: a literature review

Purpose

In epidemiological research, measurements affected by medication, for example, blood pressure lowered by antihypertensives, are common. Different ways of handling medication are required depending on the research questions and whether the affected measurement is the exposure, the outcome, or a confounder. This study aimed to review handling of medication use in observational research.

Methods

PubMed was searched for etiological studies published between 2015 and 2019 in 15 high‐ranked journals from cardiology, diabetes, and epidemiology. We selected studies that analyzed blood pressure, glucose, or lipid measurements (whether exposure, outcome or confounder) by linear or logistic regression. Two reviewers independently recorded how medication use was handled and assessed whether the methods used were in accordance with the research aim. We reported the methods used per variable category (exposure, outcome, confounder).

Results

A total of 127 articles were included. Most studies did not perform any method to account for medication use (exposure 58%, outcome 53%, and confounder 45%). Restriction (exposure 22%, outcome 23%, and confounders 10%), or adjusting for medication use using a binary indicator were also used frequently (exposure: 18%, outcome: 19%, confounder: 45%). No advanced methods were applied. In 60% of studies, the methods' validity could not be judged due to ambiguous reporting of the research aim. Invalid approaches were used in 28% of the studies, mostly when the affected variable was the outcome (36%).

Conclusion

Many studies ambiguously stated the research aim and used invalid methods to handle medication use. Researchers should consider a valid methodological approach based on their research question.

Association of MTHFR Polymorphisms with H-Type Hypertension: A Systemic Review and Network Meta-Analysis of Diagnostic Test Accuracy

Purpose

An association between MTHFR polymorphisms and H-type hypertension (H-HTN) has been investigated by epidemiological studies, but results have been inconsistent. Thus, a systematic assessment of the association was performed based on a literature review and pooled analysis, to provide stronger evidence on the effects of single nucleotide polymorphisms on H-HTN risk.

Methods

Three investigators independently retrieved relevant studies in PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), Wanfang Database, and China Biomedical Literature Database (CBM). A fixed or random effects model was selected to calculate pooled odds ratio (OR) and 95% confidence intervals (CIs). A network meta-analysis of diagnostic test and Thakkinstian's algorithm were used to select the most appropriate genetic model, along with false-positive report probability (FPRP) for noteworthy associations. All data were processed using Stata 15.0 and Meta-Disc.

Results

A total of 14 studies involving 1759 cases and 1581 controls for MTHFR were included in our meta-analysis. In a direct meta-analysis, we found that MTHFR C667T rs1801133 significantly increased the risk of H-HTN susceptibility except for an overdominant model. However, MTHFR A1298C rs1801131 polymorphism had no significant correlation with H-HTN risk. Besides, MTHFR C667T rs1801133 is a potential diagnostic biomarker for estimating H-HTN risk. The results indicated that the dominant model was an optimal diagnosis model for excluding diseases, which could reduce a missed diagnosis rate and further improve the accuracy of disease diagnosis.

Conclusion

The present result suggests that MTHFR C667T rs1801133 polymorphism is associated with H-HTN risk and may act as a promising predictive biomarker for H-HTN risk. However, further well-designed studies are warranted to confirm these results.

Hypertension genetics past, present and future applications

Essential hypertension is a complex trait where the underlying aetiology is not completely understood. Left untreated it increases the risk of severe health complications including cardiovascular and renal disease. It is almost 15 years since the first genome-wide association study for hypertension, and after a slow start there are now over 1000 blood pressure (BP) loci explaining ∼6% of the single nucleotide polymorphism-based heritability. Success in discovery of hypertension genes has provided new pathological insights and drug discovery opportunities and translated to the development of BP genetic risk scores (GRSs), facilitating population disease risk stratification. Comparing highest and lowest risk groups shows differences of 12.9 mm Hg in systolic-BP with significant differences in risk of hypertension, stroke, cardiovascular disease and myocardial infarction. GRSs are also being trialled in antihypertensive drug responses. Drug targets identified include NPR1, for which an agonist drug is currently in clinical trials. Identification of variants at the PHACTR1 locus provided insights into regulation of EDN1 in the endothelin pathway, which is aiding the development of endothelin receptor EDNRA antagonists. Drug re-purposing opportunities, including SLC5A1 and canagliflozin (a type-2 diabetes drug), are also being identified. In this review, we present key studies from the past, highlight current avenues of research and look to the future focusing on gene discovery, epigenetics, gene-environment interactions, GRSs and drug discovery. We evaluate limitations affecting BP genetics, including ancestry bias and discuss streamlining of drug target discovery and applications for treating and preventing hypertension, which will contribute to tailored precision medicine for patients.

Multi-ancestry genome-wide gene-sleep interactions identify novel loci for blood pressure

Long and short sleep duration are associated with elevated blood pressure (BP), possibly through effects on molecular pathways that influence neuroendocrine and vascular systems. To gain new insights into the genetic basis of sleep-related BP variation, we performed genome-wide gene by short or long sleep duration interaction analyses on four BP traits (systolic BP, diastolic BP, mean arterial pressure, and pulse pressure) across five ancestry groups in two stages using 2 degree of freedom (df) joint test followed by 1df test of interaction effects. Primary multi-ancestry analysis in 62,969 individuals in stage 1 identified three novel gene by sleep interactions that were replicated in an additional 59,296 individuals in stage 2 (stage 1 + 2 Pjoint < 5 × 10-8), including rs7955964 (FIGNL2/ANKRD33) that increases BP among long sleepers, and rs73493041 (SNORA26/C9orf170) and rs10406644 (KCTD15/LSM14A) that increase BP among short sleepers (Pint < 5 × 10-8). Secondary ancestry-specific analysis identified another novel gene by long sleep interaction at rs111887471 (TRPC3/KIAA1109) in individuals of African ancestry (Pint = 2 × 10-6). Combined stage 1 and 2 analyses additionally identified significant gene by long sleep interactions at 10 loci including MKLN1 and RGL3/ELAVL3 previously associated with BP, and significant gene by short sleep interactions at 10 loci including C2orf43 previously associated with BP (Pint < 10-3). 2df test also identified novel loci for BP after modeling sleep that has known functions in sleep-wake regulation, nervous and cardiometabolic systems. This study indicates that sleep and primary mechanisms regulating BP may interact to elevate BP level, suggesting novel insights into sleep-related BP regulation.

Heritability and genome-wide association study of blood pressure in Chinese adult twins

BACKGROUND

Blood pressure (BP) is an independent and important factor for chronic diseases such as cardiovascular diseases and diabetes.

METHODS

We firstly conducted twin modeling analyses to explore the heritability of BP, including systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP) and mean arterial pressure (MAP), and then performed genome-wide association studies to explore the associated genomic loci, genes, and pathways.

RESULTS

A total of 380 Chinese twin pairs were included. The AE model containing additive genetic parameter (A) and unique/non-shared environmental parameter (E) was the best fit model, with A accounting for 53.7%, 50.1%, 48.1%, and 53.3% for SBP, DBP, PP and MAP, respectively. No SNP was found to reach the genome-wide significance level (p < 5 × 10^-8 ), however, three, four, 14 and nine SNPs were found to exceed suggestive significance level (p < 1 × 10^-5 ) for SBP, DBP, PP, and MAP, respectively. And after imputation, 46, 37, 91 and 61 SNPs were found to exceed the suggestive significance level for SBP, DBP, PP, and MAP, respectively. In gene-based analysis, 53 common genes were found among SBP, DBP, PP, and MAP. In pathway enrichment analysis, 672, 706, 701, and 596 biological pathways were associated with SBP, DBP, PP, and MAP, respectively (p < 0.05).

CONCLUSION

Our study suggests that BP is moderately heritable in the Chinese population and could be mediated by a series of genomic loci, genes, and pathways. Future larger-scale studies are needed to confirm our findings.

Associations of biogeographic ancestry with hypertension traits

OBJECTIVES

Ethnic disparities in hypertension prevalence are well documented, though the influence of genetic ancestry is unclear. The aim of this study was to evaluate associations of geographic genetic ancestry with hypertension and underlying blood pressure traits.

METHODS

We tested genetically inferred ancestry proportions from five 1000 Genomes reference populations (GBR, PEL, YRI, CHB, and LWK) for association with four continuous blood pressure (BP) traits (SBP, DBP, PP, MAP) and the dichotomous outcomes hypertension and apparent treatment-resistant hypertension in 220 495 European American, 59 927 African American, and 21 273 Hispanic American individuals from the Million Veteran Program. Ethnicity stratified results were meta-analyzed to report effect estimates per 10% difference for a given ancestry proportion in all samples.

RESULTS

Percentage GBR was negatively associated with BP (P = 2.13 × 10-19, 7.92 × 10-8, 4.41 × 10-11, and 3.57 × 10-13 for SBP, DBP, PP, and MAP, respectively; coefficient range -0.10 to -0.21 mmHg per 10% increase in ancestry proportion) and was protective against hypertension [P = 2.59 × 10-5, odds ratio (OR) = 0.98] relative to other ancestries. YRI percentage was positively associated with BP (P = 1.63 × 10-23, 1.94 × 10-26, 0.012, and 3.26 × 10-29 for SBP, DBP, PP, and MAP, respectively; coefficient range 0.06-0.32 mmHg per 10% increase in ancestry proportion) and was positively associated with hypertension risk (P = 3.10 × 10-11, OR = 1.04) and apparent treatment-resistant hypertension risk (P = 1.86 × 10-4, OR = 1.04) compared with other ancestries. Percentage PEL was inversely associated with DBP (P = 2.84 × 10-5, beta = -0.11 mmHg per 10% increase in ancestry proportion).

CONCLUSION

These results demonstrate that risk for BP traits varies significantly by genetic ancestry. Our findings provide insight into the geographic origin of genetic factors underlying hypertension risk and establish that a portion of BP trait ethnic disparities are because of genetic differences between ancestries.

Non-coding Single Nucleotide Variants of Renin and the (Pro)renin Receptor are Associated with Polygenic Diseases in a Bangladeshi Population

Non-coding variants or single-nucleotide polymorphisms (SNPs) play pivotal roles in orchestrating pathogeneses of polygenic diseases, including hypertension (HTN) and diabetes. Renin-angiotensin system (RAS) components-renin and (pro)renin receptor [(P)RR]-maintain homeostasis of body fluids. Genetic variants of RAS components are associated with risk of HTN and type 2 diabetes (T2D) in different ethnic groups. We identified associations of SNPs within the renin and (P)RR genes with HTN, T2D, and T2D-associated hypertension in 911 unrelated Bangladeshi individuals. Five non-coding SNPs were involved in modulating regulatory elements in diverse cell types when tagged with other SNPs. rs61827960 was not associated with any disease; rs3730102 was associated with increased risk of HTN and T2D while under dominant model, it showed protective role against T2D-associated HTN. SNP rs11571079 was associated with increased risk of HTN and T2D-associated HTN and decreased risk of T2D, exerting a protective effect. Renin haplotypes GCA and GTG were related to increased risk of T2D and T2D-associated HTN, respectively. Heterogeneous linkage of genotypic and allelic frequencies of rs2968915 and rs3112298 of (P)RR was observed. The (P)RR haplotype GA was associated with increased risk of HTN and significantly decreased risk of T2D. These findings highlight important roles of non-coding variants of renin and (P)RR genes in the etiology of several polygenic diseases.

Polygenic Risk Scores Predict Hypertension Onset and Cardiovascular Risk

[Figure: see text].

Comparison of the associations between appendicular lean mass adjustment methods and cardiometabolic factors

BACKGROUND AND AIMS

To compare the cross-sectional and longitudinal associations between appendicular lean mass (ALM) and cardiometabolic risk factors according to body-size adjustment methods and the contributions of genetic and/or environmental factors to the correlations between those traits.

METHODS AND RESULTS

Regression coefficients per sex-specific 1 standard deviation in bodyweight (wt), body mass index (BMI), or height-squared (ht²) adjusted ALM (assessed using a dual-energy X-ray absorptiometer (DXA) and a bioelectrical impedance analyzer (BIA) at baseline)/changes in these indices (assessed using BIA) were compared in terms of their associations with blood pressure (BP), lipid profiles, and insulin resistance profiles in 2655 participants for cross-sectional analysis and 332 participants for longitudinal analysis (follow-up time, 32.2 ± 7.9 months). A bivariate genetic analysis of the genetic/environmental cross-trait correlations was conducted to determine their cross-sectional relationships. After adjusting for sociodemographic factors, health behaviors, and BMI in the analysis for ALM/ht², ALM/wt and ALM/BMI had favorable associations with all cardiometabolic risk factors, while ALM/ht² had favorable associations with some risk factors. In longitudinal associations, changes in ALM/wt and ALM/BMI had inverse associations with increments of lipid profiles, insulin, and homeostasis model assessment of insulin resistance (HOMA), while change in ALM/ht² did not have associations with increments of cardiometabolic risk factors. ALM/ht² had genetic correlations with seven of nine risk factors; ALM/wt and ALM/BMI had correlations with three and one risk factors, respectively.

CONCLUSION

ALM/wt and ALM/BMI are better indicators for cardiometabolic risk factors; genetic factors may contribute more to the correlations between ALM/ht² and those traits.

Obesity status modifies the association between rs7556897T>C in the intergenic region SLC19A3-CCL20 and blood pressure in French children

Background Growing evidence reports an association between inflammatory markers, obesity and blood pressure (BP). Specifically, the intergenic single nucleotide polymorphism (SNP) rs7556897T > C (MAF = 0.34) located between SLC19A3 and the CCL20 was shown to be associated with chronic inflammatory diseases. In addition, CCL20 expression was found increased in pancreatic islets of obese rodents and human pancreatic β cells under the influence of inflammation. In this study, we hypothesized that SNP rs7556897 could affect BP levels, thus providing a link between inflammation, BP and obesity. Methods BP was measured under supine position with a manual sphygmomanometer; values reported were the means of three readings. We analyzed rs7556897 in 577 normal weight and 689 obese French children. Using real-time polymerase chain reaction (PCR), we quantified CCL20 and SLC19A3 expression in adipose tissue and peripheral blood mononuclear cells (PBMCs) of normal weight and overweight children. Results The rs7556897C allele was negatively associated with diastolic BP in normal weight children (β = -0.012 ± 0.004, p = 0.006) but positively associated in obese children (β = 2.178 ± 0.71, p = 0.002). A significant interaction between rs7556897T > C and the obesity status (obese or normal weight) was detected (β = 3.49, p = 9.79 × 10-5) for BP in a combined population analysis. CCL20 mRNA was only expressed in the adipose tissue of overweight children, and its expression levels were 10.7×  higher in PBMCs of overweight children than normal weight children. Finally, CCL20 mRNA levels were positively associated with rs7556897T > C in PBMCs of 58 normal weight children (β = 0.43, p = 0.002). SLC19A3 was not expressed in PBMCs, and in adipose tissue, it showed same levels of expression in normal weight and overweight children. The gene expression results may highlight a specific involvement of CCL20 via communicating obesity/inflammation pathways that regulate BP. Conclusions Childhood obesity reverses the effect of rs7556897T > C on diastolic BP, possibly via the modulation of CCL20 expression levels.

Identification of Genetic Factors Underlying the Association between Sodium Intake Habits and Hypertension Risk

The role of sodium in hypertension remains unresolved. Although genetic factors have a significant impact on high blood pressure, studies comparing genetic susceptibility between people with low and high sodium diets are lacking. We aimed to investigate the genetic variations related to hypertension according to sodium intake habits in a large Korean population-based study. Data for a total of 57,363 participants in the Korean Genome and Epidemiology Study Health Examination were analyzed. Sodium intake was measured by a semi-quantitative food frequency questionnaire. We classified participants according to sodium intake being less than or greater than 2 g/day. We used logistic regression to test single-marker variants for genetic association with a diagnosis of hypertension, adjusting for age, sex, body mass index, exercise, alcohol, smoking, potassium intake, principal components 1, and principal components 2. Significant associations were defined as p < 5 × 10⁻⁸. In participants whose sodium intake was greater than 2 g/day, chromosome 6 open reading frame 10 (C6orf10)-human leukocyte antigen (HLA)-DQB1 rs6913309, ring finger protein (RNF)213 rs112735431, glycosylphosphatidylinositol anchored molecule-like (GML)- cytochrome P450 family 11 subfamily B member 1(CYP11B1) rs3819496, myosin light chain 2 (MYL2)-cut like homeobox 2 (CUX2) rs12229654, and jagged1 (JAG1) rs1887320 were significantly associated with hypertension. In participants whose intake was less than 2 g/day, echinoderm microtubule-associated protein-like 6(EML6) rs67617923 was significantly associated with hypertension. Genetic susceptibility associated with hypertension differed according to sodium intake. Identifying gene variants that contribute to the dependence of hypertension on sodium intake status could make possible more individualized nutritional recommendations for preventing cardiovascular diseases.

Learning genetic and environmental graphical models from family data

Many challenging problems in biomedical research rely on understanding how variables are associated with each other and influenced by genetic and environmental factors. Probabilistic graphical models (PGMs) are widely acknowledged as a very natural and formal language to describe relationships among variables and have been extensively used for studying complex diseases and traits. In this work, we propose methods that leverage observational Gaussian family data for learning a decomposition of undirected and directed acyclic PGMs according to the influence of genetic and environmental factors. Many structure learning algorithms are strongly based on a conditional independence test. For independent measurements of normally distributed variables, conditional independence can be tested through standard tests for zero partial correlation. In family data, the assumption of independent measurements does not hold since related individuals are correlated due to mainly genetic factors. Based on univariate polygenic linear mixed models, we propose tests that account for the familial dependence structure and allow us to assess the significance of the partial correlation due to genetic (between-family) factors and due to other factors, denoted here as environmental (within-family) factors, separately. Then, we extend standard structure learning algorithms, including the IC/PC and the really fast causal inference (RFCI) algorithms, to Gaussian family data. The algorithms learn the most likely PGM and its decomposition into two components, one explained by genetic factors and the other by environmental factors. The proposed methods are evaluated by simulation studies and applied to the Genetic Analysis Workshop 13 simulated dataset, which captures significant features of the Framingham Heart Study.

Impact of Overweight in Mens with Family History of Hypertension: Early Heart Rate Variability and Oxidative Stress Disarrangements

Aim

To evaluate cardiovascular, autonomic, and oxidative stress markers in eutrophic and overweight offspring of hypertensive parents comparing them to eutrophic and overweight offspring of normotensive parents.

Methods

We conducted a cross-sectional study. We selected 71 male and sedentary subjects, divided into 4 groups: eutrophic group with a negative family history of hypertension (EH-, n = 18) or positive family history of hypertension (EH+, n = 17), overweight group with a negative family history of hypertension (OH-, n = 19) or a positive family history of hypertension (OH+, n = 17), and aged between 18 and 35 years.

Results

Blood glucose was higher in the OH+ group when compared to other groups. Diastolic blood pressure was increased in OH- and OH+ groups when compared to eutrophic groups. Regarding the HRV, the LF abs was higher in OH- and OH+ groups when compared to the EH- group. LF/HF values were higher in EH+ and OH+ groups when compared to the EH- and OH- groups. As to oxidative stress and the metabolism of nitric oxide, we observed an increase in hydrogen peroxide and nitrite levels in the OH+ group, and in the NADPH oxidase in OH- and OH+ groups when compared to the other groups.

Conclusion

Our findings demonstrate that the overweight group with a family history of hypertension presented all the dysfunctions observed in isolation from these risk factors. We observed an exacerbation of cardiac sympathetic modulation and early prooxidants increase, which may be associated with target organ damage and cardiovascular risk in this population.

[Partially French Canadians are susceptible to increased cardiovascular risk factors: A population-based retrospective cohort study]

BACKGROUND

Through various research lead in the past, it has been made evident that Quebec is home to higher rates of acute myocardial infarction (AMI) and higher prevalence of cardiovascular risk factors than other Canadian provinces. This proposed study will perform a retrospective analysis on Caucasian populations in order to analyze the cardiovascular risk factors in partially francophone populations in comparison to French and Non-French Canadians. Furthermore, we will closely analyze both genders of aforementioned populations.

METHODS

This population-based retrospective cohort study was achieved using the University of Ottawa Heart Institute CCTA registry. Included are Caucasian patients of all ages who came to UOHI for a CCTA between 2006 and 2018 and provided written informed consent. SPSS was used to compare the different populations (French Canadian, partially French Canadian and non-French Canadian) and sex.

RESULTS

The PFC population more closely resembles FC, having higher incidence of cardiovascular risk factors such as smoking, dyslipidemia and type 2 diabetes.

INTERPRETATION

Our results suggest that PFC, like FC, may benefit from more intensive education and lifestyle modification techniques.

Trajectories of Non-HDL Cholesterol Across Midlife: Implications for Cardiovascular Prevention

BACKGROUND

Extended elevations of non-high-density lipoprotein cholesterol (non-HDL-C) across a lifespan are associated with increased risk of cardiovascular disease (CVD). However, optimal testing intervals to identify individuals with high lipid-related CVD risk are unknown.

OBJECTIVES

This study determined the extent to which lipid levels in young adulthood predict future lipid trajectories and associated long-term CVD risk.

METHODS

A sample of 2,516 Framingham Offspring study participants 25 to 40 years of age free of CVD and diabetes had their non-HDL-C progression modeled over 8 study examinations (mean follow-up 32.6 years) using group-based methods. CVD risk based on 25 to 30 years of follow-up was evaluated using Kaplan-Meier analyses for those with mean non-HDL-C ≥160 mg/dl ("high") and <130 mg/dl ("low") at the first 2 examinations. Levels of non-HDL-C for participants on lipid treatment were adjusted by nonparametric algorithm.

RESULTS

The trajectories of the lipid levels were generally stable over the 30-year life course; mean non-HDL-C measured in young adulthood were highly predictive of levels later in life. Individuals could be reliably assigned to high and low non-HDL-C groups based on 2 measurements collected between 25 to 40 years of age. Overall, 80% of those with non-HDL-C ≥160 mg/dl at the first 2 exams remained in the high group on subsequent 25-year testing, whereas 88% of those with non-HDL-C <130 mg/dl remained below 160 mg/dl. Those with high non-HDL-C in young adulthood had a 22.6% risk of CVD in the next 25 years as compared with a 6.4% risk in those with low non-HDL-C.

CONCLUSIONS

Most adults with elevated non-HDL-C early in life continue to have high non-HDL-C over their life course, leading to significantly increased risk of CVD. The results demonstrate that early lipid monitoring before 40 years of age would identify a majority of those with a high likelihood for lifetime elevated lipid levels who also have a high long-term risk for CVD. This information could facilitate informed patient-provider discussion about the potential benefits of preventive lipid-lowering efforts during the early midlife period.

Quantifying Importance of Major Risk Factors for Coronary Heart Disease

Supplemental Digital Content is available in the text.

Background:

To optimize preventive strategies for coronary heart disease (CHD), it is essential to understand and appropriately quantify the contribution of its key risk factors. Our objective was to compare the associations of key modifiable CHD risk factors—specifically lipids, systolic blood pressure (SBP), diabetes mellitus, and smoking—with incident CHD events based on their prognostic performance, attributable risk fractions, and treatment benefits, overall and by age.

Methods:

Pooled participant-level data from 4 observational cohort studies sponsored by the National Heart, Lung, and Blood Institute were used to create a cohort of 22 626 individuals aged 45 to 84 years who were initially free of cardiovascular disease. Individuals were followed for 10 years from baseline evaluation for incident CHD. Proportional hazards regression was used to estimate metrics of prognostic model performance (likelihood ratio, C index, net reclassification, discrimination slope), hazard ratios, and population attributable fractions for SBP, non–high-density lipoprotein cholesterol (non–HDL-C), diabetes mellitus, and smoking. Expected absolute risk reductions for antihypertensive and lipid-lowering treatment were assessed.

Results:

Age, sex, and race capture 63% to 80% of the prognostic performance of cardiovascular risk models. In contrast, adding either SBP, non–HDL-C, diabetes mellitus, or smoking to a model with other risk factors increases the C index by only 0.004 to 0.013. However, primordial prevention could have a substantial effect as demonstrated by population attributable fractions of 28% for SBP≥130 mm Hg and 17% for non–HDL-C≥130 mg/dL. Similarly, lowering the SBP of all individuals to <130 mm Hg or lowering low-density lipoprotein cholesterol by 30% would be expected to lower a baseline 10-year CHD risk of 10.7% to 7.0 and 8.0, respectively (absolute risk reductions: 3.7% and 2.7%, respectively). Prognostic performance decreases with age (C indices for age groups 45–54, 55–64, 65–74, 75–84 are 0.75, 0.72, 0.66, and 0.62, respectively), whereas absolute risk reductions increase (SBP: 1.1%, 2.3%, 5.4%, 10.3%, respectively; non–HDL-C: 1.1%, 2.0%, 3.7%, 5.9%, respectively).

Conclusions:

Although individual modifiable CHD risk factors contribute only modestly to prognostic performance, our models indicate that eliminating or controlling these individual factors would lead to substantial reductions in total population CHD events. Metrics used to judge importance of risk factors should be tailored to the research objectives.

Lipidomic profiling identifies signatures of metabolic risk

BACKGROUND

Metabolic syndrome (MetS), the clustering of metabolic risk factors, is associated with cardiovascular disease risk. We sought to determine if dysregulation of the lipidome may contribute to metabolic risk factors.

METHODS

We measured 154 circulating lipid species in 658 participants from the Framingham Heart Study (FHS) using liquid chromatography-tandem mass spectrometry and tested for associations with obesity, dysglycemia, and dyslipidemia. Independent external validation was sought in three independent cohorts. Follow-up data from the FHS were used to test for lipid metabolites associated with longitudinal changes in metabolic risk factors.

RESULTS

Thirty-nine lipids were associated with obesity and eight with dysglycemia in the FHS. Of 32 lipids that were available for replication for obesity and six for dyslipidemia, 28 (88%) replicated for obesity and five (83%) for dysglycemia. Four lipids were associated with longitudinal changes in body mass index and four were associated with changes in fasting blood glucose in the FHS.

CONCLUSIONS

We identified and replicated several novel lipid biomarkers of key metabolic traits. The lipid moieties identified in this study are involved in biological pathways of metabolic risk and can be explored for prognostic and therapeutic utility.

Genetic Ablation and Guanylyl Cyclase/Natriuretic Peptide Receptor-A: Impact on the Pathophysiology of Cardiovascular Dysfunction

Mice bearing targeted gene mutations that affect the functions of natriuretic peptides (NPs) and natriuretic peptide receptors (NPRs) have contributed important information on the pathogenesis of hypertension, kidney disease, and cardiovascular dysfunction. Studies of mice having both complete gene disruption and tissue-specific gene ablation have contributed to our understanding of hypertension and cardiovascular disorders. These phenomena are consistent with an oligogenic inheritance in which interactions among a few alleles may account for genetic susceptibility to hypertension, renal insufficiency, and congestive heart failure. In addition to gene knockouts conferring increased risks of hypertension, kidney disorders, and cardiovascular dysfunction, studies of gene duplications have identified mutations that protect against high blood pressure and cardiovascular events, thus generating the notion that certain alleles can confer resistance to hypertension and heart disease. This review focuses on the intriguing phenotypes of Npr1 gene disruption and gene duplication in mice, with emphasis on hypertension and cardiovascular events using mouse models carrying Npr1 gene knockout and/or gene duplication. It also describes how Npr1 gene targeting in mice has contributed to our knowledge of the roles of NPs and NPRs in dose-dependently regulating hypertension and cardiovascular events.

Hypertension Across a Woman's Life Cycle

Hypertension accounts for 1 in 5 deaths among American women, posing a greater burden for women than men, and is among their most important risk factors for death and development of cardiovascular and other diseases. Hypertension affects women in all phases of life, with specific characteristics relating to risk factors and management for primary prevention of hypertension in teenage and young adult women; hypertension in pregnancy; hypertension during use of oral contraceptives and assisted reproductive technologies, lactation, menopause, or hormone replacement; hypertension in elderly women; and issues of race and ethnicity. All are detailed in this review, as is information relative to women in clinical trials of hypertension and medication issues. The overarching message is that effective treatment and control of hypertension improves cardiovascular outcomes. But many knowledge gaps persist, including the contribution of hypertensive disorders of pregnancy to cardiovascular disease risk, the role of hormone replacement, blood pressure targets for elderly women, and so on.

Vascular Smooth Muscle Remodeling in Conductive and Resistance Arteries in Hypertension

Cardiovascular disease is a leading cause of death worldwide and accounts for >17.3 million deaths per year, with an estimated increase in incidence to 23.6 million by 2030. ¹ Cardiovascular death represents 31% of all global deaths ² -with stroke, heart attack, and ruptured aneurysms predominantly contributing to these high mortality rates. A key risk factor for cardiovascular disease is hypertension. Although treatment or reduction in hypertension can prevent the onset of cardiovascular events, existing therapies are only partially effective. A key pathological hallmark of hypertension is increased peripheral vascular resistance because of structural and functional changes in large (conductive) and small (resistance) arteries. In this review, we discuss the clinical implications of vascular remodeling, compare the differences between vascular smooth muscle cell remodeling in conductive and resistance arteries, discuss the genetic factors associated with vascular smooth muscle cell function in hypertensive patients, and provide a prospective assessment of current and future research and pharmacological targets for the treatment of hypertension.

Familial clustering of hypertensive target organ damage in the community

OBJECTIVES

Prior studies suggest that hypertensive target organ damage (TOD) is a heritable trait. However, the risk that parental TOD confers on propensity for TOD in their offspring, and how hypertensive TOD clusters in the context of parental versus offspring hypertension status remain unclear.

METHODS

We studied 3238 Framingham Heart Study participants (mean age 39 ± 8 years, 53% women) with available parental data on TOD. Parents and offspring underwent measurements for left ventricular hypertrophy, increased relative wall thickness, albuminuria and conventional risk factors.

RESULTS

Prevalence of any TOD (left ventricular hypertrophy or albuminuria) in participants with zero and at least one parents with any TOD was 7 and 13%, respectively (P < 0.001 for difference). Having at least one parent with TOD was associated with greater odds of TOD in offspring than individuals without parental TOD [multivariable-adjusted odds ratio (OR), 1.65; 95% confidence interval (95% CI), 1.27-2.14]. Similarly, parental left ventricular hypertrophy was associated with offspring left ventricular hypertrophy (OR, 2.73; 95% CI 1.92-3.89), parental increased relative wall thickness conferred increased odds of increased relative wall thickness in the offspring (OR, 1.54; 95% CI 1.16-2.04) and parental albuminuria was related to offspring albuminuria (OR, 1.49; 95% CI 1.03-2.16). These associations remained significant upon adjustment for other risk factors, including blood pressure, and in analyses of subgroups defined according to parental or offspring hypertension status.

CONCLUSION

Overall, our data suggest that familial clustering of TOD in the community is independent of blood pressure. Additional studies are warranted to confirm our observations.

The association of elevated maternal genetic risk scores for hypertension, type 2 diabetes and obesity and having a child with a congenital heart defect

Background

Maternal hypertension, type 2 diabetes (T2D) and obesity are associated with an increased risk of having offspring with conotruncal heart defects (CTDs). Prior studies have identified sets of single nucleotide polymorphisms (SNPs) that are associated with risk for each of these three adult phenotypes. We hypothesized that these same SNPs are associated with maternal risk of CTDs in offspring.

Methods and results

We evaluated the parents of children with a CTD ascertained from the Children’s Hospital of Philadelphia (n = 466) and by the Pediatric Cardiac Genomic Consortium (n = 255). We used a family-based design to assess the association between CTDs and the maternal genotype for individual hypertension, T2D, and obesity-related SNPs and found no association between CTDs and the maternal genotype for any individual SNP. In addition, we calculated genetic risk scores (GRS) for hypertension, T2D, and obesity using previously published GRS formulas. When comparing the GRS of mothers to fathers, there were no statistically significant differences in the mean for the combined GRS or the GRS for each individual condition. However, when we categorized the mothers and fathers of cases with CTDs as having high (>95^th percentile) or low (≤95^th percentile) scores, compared to fathers, mothers had almost two times the odds of having a high GRS for hypertension (OR 1.7, 95% CI 1.0, 2.8) and T2D (OR 1.8, 95% CI 1.1, 3.1).

Conclusions

Our results support a link between maternal genetic risk for hypertension/T2D and CTDs in their offspring. These associations might be independent of maternal phenotype at conception.

A Social Determinant of Health May Modify Genetic Associations for Blood Pressure: Evidence From a SNP by Education Interaction in an African American Population

African Americans experience the highest burden of hypertension in the United States compared with other groups. Genetic contributions to this complex condition are now emerging in this as well as other populations through large-scale genome-wide association studies (GWAS) and meta-analyses. Despite these recent discovery efforts, relatively few large-scale studies of blood pressure have considered the joint influence of genetics and social determinants of health despite extensive evidence supporting their impact on hypertension. To identify these expected interactions, we accessed a subset of the Vanderbilt University Medical Center (VUMC) biorepository linked to de-identified electronic health records (EHRs) of adult African Americans genotyped using the Illumina Metabochip (n = 2,577). To examine potential interactions between education, a recognized social determinant of health, and genetic variants contributing to blood pressure, we used linear regression models to investigate two-way interactions for systolic and diastolic blood pressure (DBP). We identified a two-way interaction between rs6687976 and education affecting DBP (p = 0.052). Individuals homozygous for the minor allele and having less than a high school education had higher DBP compared with (1) individuals homozygous for the minor allele and high school education or greater and (2) individuals not homozygous for the minor allele and less than a high school education. To our knowledge, this is the first EHR -based study to suggest a gene-environment interaction for blood pressure in African Americans, supporting the hypothesis that genetic contributions to hypertension may be modulated by social factors.

Resistant Hypertension: Detection, Evaluation, and Management: A Scientific Statement From the American Heart Association

Resistant hypertension (RH) is defined as above-goal elevated blood pressure (BP) in a patient despite the concurrent use of 3 antihypertensive drug classes, commonly including a long-acting calcium channel blocker, a blocker of the renin-angiotensin system (angiotensin-converting enzyme inhibitor or angiotensin receptor blocker), and a diuretic. The antihypertensive drugs should be administered at maximum or maximally tolerated daily doses. RH also includes patients whose BP achieves target values on ≥4 antihypertensive medications. The diagnosis of RH requires assurance of antihypertensive medication adherence and exclusion of the "white-coat effect" (office BP above goal but out-of-office BP at or below target). The importance of RH is underscored by the associated risk of adverse outcomes compared with non-RH. This article is an updated American Heart Association scientific statement on the detection, evaluation, and management of RH. Once antihypertensive medication adherence is confirmed and out-of-office BP recordings exclude a white-coat effect, evaluation includes identification of contributing lifestyle issues, detection of drugs interfering with antihypertensive medication effectiveness, screening for secondary hypertension, and assessment of target organ damage. Management of RH includes maximization of lifestyle interventions, use of long-acting thiazide-like diuretics (chlorthalidone or indapamide), addition of a mineralocorticoid receptor antagonist (spironolactone or eplerenone), and, if BP remains elevated, stepwise addition of antihypertensive drugs with complementary mechanisms of action to lower BP. If BP remains uncontrolled, referral to a hypertension specialist is advised.

SHIP-AHOY (Study of High Blood Pressure in Pediatrics: Adult Hypertension Onset in Youth)

Although hypertension is identifiable in children and adolescents, there are many knowledge gaps on how to best define and manage high blood pressure in the young. SHIP-AHOY (Study of High Blood Pressure in Pediatrics: Adult Hypertension Onset in Youth) is being conducted to address these knowledge gaps. Five hundred adolescents will be recruited and will undergo ambulatory blood pressure monitoring, echocardiographic, vascular, and cognitive assessments, as well as epigenetic studies to identify mechanisms that underlie the development of hypertensive target organ damage. Details of the design and methods that will be utilized in SHIP-AHOY are presented here, as well as baseline characteristics of the first 264 study participants. The primary aim of the study is to develop a risk-based definition of hypertension in the young that will result in better understanding of the transition from blood pressure in youth to adult cardiovascular disease.

Inflammation, Immunity, and Oxidative Stress in Hypertension-Partners in Crime?

Hypertension is considered as the most common risk factor for cardiovascular disease. Inflammatory processes link hypertension and cardiovascular disease, and participate in their pathophysiology. In recent years, there has been an increase in research focused on unraveling the role of inflammation and immune activation in development and maintenance of hypertension. Although inflammation is known to be associated with hypertension, whether inflammation is a cause or effect of hypertension remains to be elucidated. This review describes the recent studies that link inflammation and hypertension and demonstrate the involvement of oxidative stress and endothelial dysfunction-two of the key processes in the development of hypertension. Etiology of hypertension, including novel immune cell subtypes, cytokines, toll-like receptors, inflammasomes, and gut microbiome, found to be associated with inflammation and hypertension are summarized and discussed. Most recent findings in this field are presented with special emphasis on potential of anti-inflammatory drugs and statins for treatment of hypertension.

Interactions of CDH13 gene polymorphisms and ambient PM10 air pollution exposure with blood pressure and hypertension in Korean men

Associations between air pollution and blood pressure (BP) traits can be modified by several candidate genes, which might explain differences in individual genetic susceptibility. Based on recent evidence hypothesized to link air pollution and BP traits, we examined whether the polymorphisms of CDH13-a candidate gene-would modify the relationship between them in adult Korean men. A total of 1816 subjects were included. We divided them into two groups of high or low to moderate exposure using the annual average concentration of particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀). We conducted an interaction analysis of PM₁₀ exposure using 200 single-nucleotide polymorphisms (SNPs), located within CDH13, in subjects with regard to BP traits and hypertension. The rs7500599 intronic SNP of CDH13 had the strongest signals for all BP traits including systolic blood pressure (SBP), diastolic blood pressure, and hypertension, by interacting with PM₁₀ exposure. An additional stratified analysis showed that the effects of PM₁₀ exposure on elevated BP and hypertension increased gradually in proportion to the number of minor alleles in this SNP. In addition, PM₁₀ exposure in the TT or GT genotype groups did not show significant associations with BP traits, whereas in a homozygous risk allele (GG) group, PM₁₀ exposure was significantly associated with BP traits and hypertension. For SBP, these patterns were reproducible at two independent sampling sites. This CDH13 polymorphism amplifies the negative associations of PM₁₀ exposure and elevated BP or hypertension in Korean men.

Molecular and genetic aspects of guanylyl cyclase natriuretic peptide receptor-A in regulation of blood pressure and renal function

Natriuretic peptides (NPs) exert diverse effects on several biological and physiological systems, such as kidney function, neural and endocrine signaling, energy metabolism, and cardiovascular function, playing pivotal roles in the regulation of blood pressure (BP) and cardiac and vascular homeostasis. NPs are collectively known as anti-hypertensive hormones and their main functions are directed toward eliciting natriuretic/diuretic, vasorelaxant, anti-proliferative, anti-inflammatory, and anti-hypertrophic effects, thereby, regulating the fluid volume, BP, and renal and cardiovascular conditions. Interactions of NPs with their cognate receptors display a central role in all aspects of cellular, biochemical, and molecular mechanisms that govern physiology and pathophysiology of BP and cardiovascular events. Among the NPs atrial and brain natriuretic peptides (ANP and BNP) activate guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) and initiate intracellular signaling. The genetic disruption of Npr1 (encoding GC-A/NPRA) in mice exhibits high BP and hypertensive heart disease that is seen in untreated hypertensive subjects, including high BP and heart failure. There has been a surge of interest in the NPs and their receptors and a wealth of information have emerged in the last four decades, including molecular structure, signaling mechanisms, altered phenotypic characterization of transgenic and gene-targeted animal models, and genetic analyses in humans. The major goal of the present review is to emphasize and summarize the critical findings and recent discoveries regarding the molecular and genetic regulation of NPs, physiological metabolic functions, and the signaling of receptor GC-A/NPRA with emphasis on the BP regulation and renal and cardiovascular disorders.

Contributions of rare coding variants in hypotension syndrome genes to population blood pressure variation

Rare variants, in particular renal salt handling genes, contribute to monogenic forms of hypertension and hypotension syndromes with electrolyte abnormalities. A study by Ji et al (2008) demonstrated this effect for rare loss-of-function coding variants in SLC12A3 (NCCT), SLC12A1 (NKCC2), and KCNJ1 (ROMK) that led to reduction of ∼6 mm Hg for SBP and ∼3 mm Hg for DBP among carriers in 2492 European ancestry Framingham Heart Study (FHS) subjects. These findings support a potentially large role for these variants in interindividual variation in systolic and diastolic blood pressure (SBP, DBP) in the population. The present study focuses on replicating the analyses completed by Ji et al to identify effects of rare variants in the population-based Atherosclerosis Risk in Communities (ARIC) study.We attempted to replicate the findings by Ji et al by applying their criteria to identify putative loss-of-function variants with allele frequency <0.001 and complete conservation across a set of orthologs, to exome sequencing data from 7444 European ancestry participants of the ARIC study.Although we failed to replicate the previous findings when applying their methods to the ARIC study data, we observed a similar effect when we restricted analyses to the subset of variants they observed.These results simultaneously support the utility of exome sequencing data for studying extremely rare coding variants in hypertension and underscore the need for improved filtering methods for identifying functional variants in human sequences.

Genetics of Resistant Hypertension: the Missing Heritability and Opportunities

PURPOSE OF THE REVIEW

Blood pressure regulation in humans has long been known to be a genetically determined trait. The identification of causal genetic modulators for this trait has been unfulfilling at the least. Despite the recent advances of genome-wide genetic studies, loci associated with hypertension or blood pressure still explain a very low percentage of the overall variation of blood pressure in the general population. This has precluded the translation of discoveries in the genetics of human hypertension to clinical use. Here, we propose the combined use of resistant hypertension as a trait for mapping genetic determinants in humans and the integration of new large-scale technologies to approach in model systems the multidimensional nature of the problem.

RECENT FINDINGS

New large-scale efforts in the genetic and genomic arenas are paving the way for an increased and granular understanding of genetic determinants of hypertension. New technologies for whole genome sequence and large-scale forward genetic screens can help prioritize gene and gene-pathways for downstream characterization and large-scale population studies, and guided pharmacological design can be used to drive discoveries to the translational application through better risk stratification and new therapeutic approaches. Although significant challenges remain in the mapping and identification of genetic determinants of hypertension, new large-scale technological approaches have been proposed to surpass some of the shortcomings that have limited progress in the area for the last three decades. The incorporation of these technologies to hypertension research may significantly help in the understanding of inter-individual blood pressure variation and the deployment of new phenotyping and treatment approaches for the condition.

A Two-Stage Whole-Genome Gene Expression Association Study of Young-Onset Hypertension in Han Chinese Population of Taiwan

Hypertension is an important public health problem in the world. Since the intermediate position of the gene expression between genotype and phenotype makes it suitable to link genotype to phenotype, we carried out a two-stage whole-genome gene expression association study to find differentially expressed genes and pathways for hypertension. In the first stage, 126 cases and 149 controls were used to find out the differentially expressed genes. In the second stage, an independent set of samples (127 cases and 150 controls) was used to validate the results. Additionally, we conducted a gene set enrichment analysis (GSEA) to search for differentially affected pathways. A total of nine genes were implicated in the first stage (Bonferroni-corrected p-value < 0.05). Among these genes, ZRANB1, FAM110A, PREP, ANKRD9 and LAMB2 were also differentially expressed in an existing database of hypertensive mouse model (GSE19817). A total of 16 pathways were identified by the GSEA. ZRANB1 and six pathways identified are related to TNF-α. Three pathways are related to interleukin, one to metabolic syndrome, and one to Hedgehog signaling. Identification of these genes and pathways suggest the importance of 1. inflammation, 2. visceral fat metabolism, and 3. adipocytes and osteocytes homeostasis in hypertension mechanisms and complications.

DNA Methylation Analysis Identifies Loci for Blood Pressure Regulation

Genome-wide association studies have identified hundreds of genetic variants associated with blood pressure (BP), but sequence variation accounts for a small fraction of the phenotypic variance. Epigenetic changes may alter the expression of genes involved in BP regulation and explain part of the missing heritability. We therefore conducted a two-stage meta-analysis of the cross-sectional associations of systolic and diastolic BP with blood-derived genome-wide DNA methylation measured on the Infinium HumanMethylation450 BeadChip in 17,010 individuals of European, African American, and Hispanic ancestry. Of 31 discovery-stage cytosine-phosphate-guanine (CpG) dinucleotides, 13 replicated after Bonferroni correction (discovery: N = 9,828, p < 1.0 × 10-7; replication: N = 7,182, p < 1.6 × 10-3). The replicated methylation sites are heritable (h2 > 30%) and independent of known BP genetic variants, explaining an additional 1.4% and 2.0% of the interindividual variation in systolic and diastolic BP, respectively. Bidirectional Mendelian randomization among up to 4,513 individuals of European ancestry from 4 cohorts suggested that methylation at cg08035323 (TAF1B-YWHAQ) influences BP, while BP influences methylation at cg00533891 (ZMIZ1), cg00574958 (CPT1A), and cg02711608 (SLC1A5). Gene expression analyses further identified six genes (TSPAN2, SLC7A11, UNC93B1, CPT1A, PTMS, and LPCAT3) with evidence of triangular associations between methylation, gene expression, and BP. Additional integrative Mendelian randomization analyses of gene expression and DNA methylation suggested that the expression of TSPAN2 is a putative mediator of association between DNA methylation at cg23999170 and BP. These findings suggest that heritable DNA methylation plays a role in regulating BP independently of previously known genetic variants.

Genome-Wide Association Study of Blood Pressure Traits by Hispanic/Latino Background: the Hispanic Community Health Study/Study of Latinos

Hypertension prevalence varies between ethnic groups, possibly due to differences in genetic, environmental, and cultural determinants. Hispanic/Latino Americans are a diverse and understudied population. We performed a genome-wide association study (GWAS) of blood pressure (BP) traits in 12,278 participants from the Hispanics Community Health Study/Study of Latinos (HCHS/SOL). In the discovery phase we identified eight previously unreported BP loci. In the replication stage, we tested these loci in the 1982 Pelotas Birth Cohort Study of admixed Southern Brazilians, the COGENT-BP study of African descent, women of European descent from the Women Health Initiative (WHI), and a sample of European descent from the UK Biobank. No loci met the Bonferroni-adjusted level of statistical significance (0.0024). Two loci had marginal evidence of replication: rs78701042 (NGF) with diastolic BP (P = 0.008 in the 1982 Pelotas Birth Cohort Study), and rs7315692 (SLC5A8) with systolic BP (P = 0.007 in European ancestry replication). We investigated whether previously reported loci associated with BP in studies of European, African, and Asian ancestry generalize to Hispanics/Latinos. Overall, 26% of the known associations in studies of individuals of European and Chinese ancestries generalized, while only a single association previously discovered in a people of African descent generalized.

Transcriptome-Wide Analysis Identifies Novel Associations With Blood Pressure

Hypertension represents a major cardiovascular risk factor. The pathophysiology of increased blood pressure (BP) is not yet completely understood. Transcriptome profiling offers possibilities to uncover genetics effects on BP. Based on 2 populations including 2549 individuals, a meta-analyses of monocytic transcriptome-wide profiles were performed to identify transcripts associated with BP. Replication was performed in 2 independent studies of whole-blood transcriptome data including 1990 individuals. For identified candidate genes, a direct link between long-term changes in BP and gene expression over time and by treatment with BP-lowering therapy was assessed. The predictive value of protein levels encoded by candidate genes for subsequent cardiovascular disease was investigated. Eight transcripts (CRIP1, MYADM, TIPARP, TSC22D3, CEBPA, F12, LMNA, and TPPP3) were identified jointly accounting for up to 13% (95% confidence interval, 8.7-16.2) of BP variability. Changes in CRIP1, MYADM, TIPARP, LMNA, TSC22D3, CEBPA, and TPPP3 expression associated with BP changes-among these, CRIP1 gene expression was additionally correlated to measures of cardiac hypertrophy. Assessment of circulating CRIP1 (cystein-rich protein 1) levels as biomarkers showed a strong association with increased risk for incident stroke (hazard ratio, 1.06; 95% confidence interval, 1.03-1.09; P=5.0×10^-5). Our comprehensive analysis of global gene expression highlights 8 novel transcripts significantly associated with BP, providing a link between gene expression and BP. Translational approaches further established evidence for the potential use of CRIP1 as emerging disease-related biomarker.

Genomic Approaches to Hypertension

Genomic insights and analyses of Mendelian hypertension (HTN) syndromes and Genome-Wide Association study (GWAS) on essential hypertension have contributed to the depth of understanding of the genetics origins of hypertension. Mendelian syndromes are important for the field, since such knowledge leads to specific insights about disease pathogenesis and the potential for precision medicine. The clinical impact of findings of on essential hypertension is continuously evolving, and the insights accrued will refine efforts to combat the societal impact of hypertension. Comprehensive identification of all genomic variants of hypertension, along with their individual associated mechanisms, is paving the way forward in the era of personalized medicine. The overriding challenge for care providers is to reduce health inequities through improved compliance and, perhaps, new paradigms for implementation science that incorporate genomic medicine.

An Exploration of Gene-Gene Interactions and Their Effects on Hypertension

Hypertension tends to perpetuate in families and the heritability of hypertension is estimated to be around 20-60%. So far, the main proportion of this heritability has not been found by single-locus genome-wide association studies. Therefore, the current study explored gene-gene interactions that have the potential to partially fill in the missing heritability. A two-stage discovery-confirmatory analysis was carried out in the Framingham Heart Study cohorts. The first stage was an exhaustive pairwise search performed in 2320 early-onset hypertensive cases with matched normotensive controls from the offspring cohort. Then, identified gene-gene interactions were assessed in an independent set of 694 subjects from the original cohort. Four unique gene-gene interactions were found to be related to hypertension. Three detected genes were recognized by previous studies, and the other 5 loci/genes (MAN1A1, LMO3, NPAP1/SNRPN, DNAL4, and RNA5SP455/KRT8P5) were novel findings, which had no strong main effect on hypertension and could not be easily identified by single-locus genome-wide studies. Also, by including the identified gene-gene interactions, more variance was explained in hypertension. Overall, our study provides evidence that the genome-wide gene-gene interaction analysis has the possibility to identify new susceptibility genes, which can provide more insights into the genetic background of blood pressure regulation.

Single-trait and multi-trait genome-wide association analyses identify novel loci for blood pressure in African-ancestry populations

Hypertension is a leading cause of global disease, mortality, and disability. While individuals of African descent suffer a disproportionate burden of hypertension and its complications, they have been underrepresented in genetic studies. To identify novel susceptibility loci for blood pressure and hypertension in people of African ancestry, we performed both single and multiple-trait genome-wide association analyses. We analyzed 21 genome-wide association studies comprised of 31,968 individuals of African ancestry, and validated our results with additional 54,395 individuals from multi-ethnic studies. These analyses identified nine loci with eleven independent variants which reached genome-wide significance (P < 1.25×10-8) for either systolic and diastolic blood pressure, hypertension, or for combined traits. Single-trait analyses identified two loci (TARID/TCF21 and LLPH/TMBIM4) and multiple-trait analyses identified one novel locus (FRMD3) for blood pressure. At these three loci, as well as at GRP20/CDH17, associated variants had alleles common only in African-ancestry populations. Functional annotation showed enrichment for genes expressed in immune and kidney cells, as well as in heart and vascular cells/tissues. Experiments driven by these findings and using angiotensin-II induced hypertension in mice showed altered kidney mRNA expression of six genes, suggesting their potential role in hypertension. Our study provides new evidence for genes related to hypertension susceptibility, and the need to study African-ancestry populations in order to identify biologic factors contributing to hypertension.

Effect of different methods of accounting for antihypertensive treatment when assessing the relationship between diabetes or obesity and systolic blood pressure

BACKGROUND

Underlying blood pressure is that observed in the absence of antihypertensive treatment or, among those treated, the estimate of that which would be observed without treatment. This study aims to examine the relationships between diabetes or obesity and underlying systolic blood pressure adjusted for antihypertensive treatment by several methods.

METHODS

Data from two population studies were analyzed-an American Indian community in Arizona and the National Health and Nutrition Examination Surveys. Antihypertensive treatment was accounted for using: no adjustment; antihypertensive use as a covariate; blood pressure dichotomized into normotension and hypertension; addition of a fixed treatment effect; non-parametric algorithm; and censored normal regression.

RESULTS

The magnitude of association at each time point differed by adjustment method particularly where there was a difference in prevalence of antihypertensive use between people with and without diabetes or obesity. The common methods of ignoring antihypertensive treatment or including it as a covariate in a regression model underestimated the effects of diabetes and obesity on underlying blood pressure, compared to the recommended method of the censored normal regression.

CONCLUSION

Proper accounting for antihypertensive treatment is needed in interpreting variables that affect blood pressure.

Genome-wide association study of generalized anxiety symptoms in the Hispanic Community Health Study/Study of Latinos

Although generalized anxiety disorder (GAD) is heritable and aggregates in families, no genomic loci associated with GAD have been reported. We aimed to discover potential loci by conducting a genome-wide analysis of GAD symptoms in a large, population-based sample of Hispanic/Latino adults. Data came from 12,282 participants (aged 18-74) in the Hispanic Community Health Study/Study of Latinos. Using a shortened Spielberger Trait Anxiety measure, we analyzed the following: (i) a GAD symptoms score restricted to the three items tapping diagnostic features of GAD as defined by DSM-V; and (ii) a total trait anxiety score based on summing responses to all ten items. We first calculated the heritability due to common variants (h²_SNP ) and then conducted a genome-wide association study (GWAS) of GAD symptoms. Replication was attempted in three independent Hispanic cohorts (Multi-Ethnic Study of Atherosclerosis, Women's Health Initiative, Army STARRS). The GAD symptoms score showed evidence of modest heritability (7.2%; P = 0.03), while the total trait anxiety score did not (4.97%; P = 0.20). One genotyped SNP (rs78602344) intronic to thrombospondin 2 (THBS2) was nominally associated (P = 5.28 × 10^-8 ) in the primary analysis adjusting for psychiatric medication use and significantly associated with the GAD symptoms score in the analysis excluding medication users (P = 4.18 × 10^-8 ). However, meta-analysis of the replication samples did not support this association. Although we identified a genome-wide significant locus in this sample, we were unable to replicate this finding. Evidence for heritability was also only detected for GAD symptoms, and not the trait anxiety measure, suggesting differential genetic influences within the domain of trait anxiety. © 2016 Wiley Periodicals, Inc.

Population differences in associations of serotonin transporter promoter polymorphism (5HTTLPR) di- and triallelic genotypes with blood pressure and hypertension prevalence

Based on prior research finding the 5HTTLPR L allele associated with increased cardiovascular reactivity to laboratory stressors and increased risk of myocardial infarction, we hypothesized that the 5HTTLPR L allele will be associated with increased blood pressure (BP) and increased hypertension prevalence in 2 large nationally representative samples in the United States and Singapore.

METHODS

Logistic regression and linear models tested associations between triallelic (L'S', based on rs25531) 5HTTLPR genotypes and hypertension severity and mean systolic and diastolic blood pressure (SBP and DBP) collected during the Wave IV survey of the National Longitudinal Study of Adolescent to Adult Health (Add Health, N=11,815) in 2008-09 and during 2004-07 in 4196 Singaporeans.

RESULTS

In US Whites, L' allele carriers had higher SBP (0.9 mm Hg, 95% CI=0.26-1.56) and greater odds (OR=1.23, 95% CI=1.10-1.38) of more severe hypertension than those with S'S' genotypes. In African Americans, L' carriers had lower mean SBP (-1.27mm Hg, 95% CI=-2.53 to -0.01) and lower odds (OR = 0.78, 95% CI=0.65-0.94) of more severe hypertension than those with the S'S' genotype. In African Americans, those with L'L' genotypes had lower DBP (-1.13mm Hg, 95% CI=-2.09 to -0.16) than S' carriers. In Native Americans, L' carriers had lower SBP (-6.05mm Hg, 95% CI=-9.59 to -2.51) and lower odds of hypertension (OR = 0.34, 95% CI=0.13-0.89) than those with the S'S' genotype. In Asian/Pacific Islanders those carrying the L' allele had lower DBP (-1.77mm Hg, 95% CI=-3.16 to -0.38) and lower odds of hypertension (OR = 0.68, 95% CI=0.48-0.96) than those with S'S'. In the Singapore sample S' carriers had higher SBP (3.02mm Hg, 95% CI=0.54-5.51) and DBP (1.90mm Hg, 95% CI=0.49-3.31) than those with the L'L' genotype.

CONCLUSIONS

These findings suggest that Whites carrying the L' allele, African Americans and Native Americans with the S'S' genotype, and Asians carrying the S' allele will be found to be at higher risk of developing cardiovascular disease and may benefit from preventive measures.

Genetic Loci and Novel Discrimination Measures Associated with Blood Pressure Variation in African Americans Living in Tallahassee

Sequencing of the human genome and decades of genetic association and linkage studies have dramatically improved our understanding of the etiology of many diseases. However, the multiple causes of complex diseases are still not well understood, in part because genetic and sociocultural risk factors are not typically investigated concurrently. Hypertension is a leading risk factor for cardiovascular disease and afflicts more African Americans than any other racially defined group in the US. Few genetic loci for hypertension have been replicated across populations, which may reflect population-specific differences in genetic variants and/or inattention to relevant sociocultural factors. Discrimination is a salient sociocultural risk factor for poor health and has been associated with hypertension. Here we use a biocultural approach to study blood pressure (BP) variation in African Americans living in Tallahassee, Florida by genotyping over 30,000 single nucleotide polymorphisms (SNPs) and capturing experiences of discrimination using novel measures of unfair treatment of self and others (n = 157). We perform a joint admixture and genetic association analysis for BP that prioritizes regions of the genome with African ancestry. We only report significant SNPs that were confirmed through our simulation analyses, which were performed to determine the false positive rate. We identify eight significant SNPs in five genes that were previously associated with cardiovascular diseases. When we include measures of unfair treatment and test for interactions between SNPs and unfair treatment, we identify a new class of genes involved in multiple phenotypes including psychosocial distress and mood disorders. Our results suggest that inclusion of culturally relevant stress measures, like unfair treatment in African Americans, may reveal new genes and biological pathways relevant to the etiology of hypertension, and may also improve our understanding of the complexity of gene-environment interactions that underlie complex diseases.