Genome-wide association study identifies eight loci associated with blood pressure

Addressing optimal folate and related B-vitamin status through the lifecycle: health impacts and challenges

The functional effects of folate within C1 metabolism involve interrelationships with vitamin B12, vitamin B6 and riboflavin, and related gene–nutrient interactions. These B vitamins have important roles throughout life, from pregnancy, through childhood, to middle and older age. Achieving optimal nutritional status for preventing folate-related disease is challenging, however, primarily as a result of the poor stability and incomplete bioavailability of folate from natural food sources when compared with the synthetic vitamin form, folic acid. Thus, in European countries, measures to prevent neural tube defects (NTD) have been largely ineffective because of the generally poor compliance of women with folic acid supplementation as recommended before and in early pregnancy. In contrast, countries worldwide with mandatory folic acid fortification policies have experienced marked reductions in NTD. Low vitamin B12 status is associated with increased risk of cognitive dysfunction, CVD and osteoporosis. Achieving optimal B12 status can be problematic for older people, however, primarily owing to food-bound B12 malabsorption which leads to sub-clinical deficiency even with high dietary B12 intakes. Optimising B-vitamin intake may be particularly important for sub-populations with impaired folate metabolism owing to genetic characteristics, most notably the 677C→T variant in the gene encoding the enzyme methylenetetrahydrofolate reductase (MTHFR). This common folate polymorphism is linked with several adverse health outcomes, including stroke, however, recent evidence has identified its novel interaction with riboflavin (the MTHFR cofactor) in relation to blood pressure and risk of developing hypertension. This review addresses why and how the optimal status of folate-related B vitamins should be achieved through the lifecycle.

Genetics of Human Primary Hypertension: Focus on Hormonal Mechanisms

Increasingly, primary hypertension is being considered a syndrome and not a disease, with the individual causes (diseases) having a common sign-an elevated blood pressure. To determine these causes, genetic tools are increasingly employed. This review identified 62 proposed genes. However, only 21 of them met our inclusion criteria: (i) primary hypertension, (ii) two or more supporting cohorts from different publications or within a single publication or one supporting cohort with a confirmatory genetically modified animal study, and (iii) 600 or more subjects in the primary cohort; when including our exclusion criteria: (i) meta-analyses or reviews, (ii) secondary and monogenic hypertension, (iii) only hypertensive complications, (iv) genes related to blood pressure but not hypertension per se, (v) nonsupporting studies more common than supporting ones, and (vi) studies that did not perform a Bonferroni or similar multiassessment correction. These 21 genes were organized in a four-tiered structure: distant phenotype (hypertension); intermediate phenotype [salt-sensitive (18) or salt-resistant (0)]; subintermediate phenotypes under salt-sensitive hypertension [normal renin (4), low renin (8), and unclassified renin (6)]; and proximate phenotypes (specific genetically driven hypertensive subgroup). Many proximate hypertensive phenotypes had a substantial endocrine component. In conclusion, primary hypertension is a syndrome; many proposed genes are likely to be false positives; and deep phenotyping will be required to determine the utility of genetics in the treatment of hypertension. However, to date, the positive genes are associated with nearly 50% of primary hypertensives, suggesting that in the near term precise, mechanistically driven treatment and prevention strategies for the specific primary hypertension subgroups are feasible.

Loss of reticulocalbin 2 lowers blood pressure and restrains ANG II-induced hypertension in vivo

Hypertension affects over 1 billion people worldwide and increases the risk for heart failure, stroke, and chronic kidney disease. Despite high prevalence and devastating impact, its etiology still remains poorly understood for most hypertensive cases. Rcn2, which encodes reticulocalbin 2, is a candidate gene for atherosclerosis that we have previously reported in mice. Here, we identified Rcn2 as a novel regulator of blood pressure in mice. Rcn2 was abundantly expressed in the endothelium and adventitia of normal arteries and was dramatically upregulated in the medial layer of the artery undergoing structural remodeling. Deletion of Rcn2 lowered basal blood pressure and attenuated ANG II-induced hypertension in C57BL/6 mice. siRNA knockdown of Rcn2 dramatically increased production of the nitric oxide (NO) breakdown products nitrite and nitrate by endothelial cells but not by smooth muscle cells. Isolated carotid arteries from Rcn2-/- mice showed an increased sensitivity to the ACh-induced NO-mediated relaxant response compared with arteries of Rcn2+/+ mice. Analysis of a recent meta-data set showed associations of genetic variants near RCN2 with blood pressure in humans. These data suggest that Rcn2 regulates blood pressure and contributes to hypertension through actions on endothelial NO synthase.

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.

Proximal Tubule-Specific Deletion of the NHE3 (Na+/H+ Exchanger 3) Promotes the Pressure-Natriuresis Response and Lowers Blood Pressure in Mice

The present study directly tested the hypothesis that deletion of the NHE3 (Na⁺/H⁺ exchanger 3) selectively in the proximal tubules of the kidney lowers basal blood pressure by increasing the pressure-natriuresis response in mice. Adult male and female, age-matched wild-type (WT) littermates and proximal tubule-specific NHE3 knockout mice (PT- Nhe3^-/-; n=6-16 per group) were studied for (1) basal phenotypes of electrolytes and pH, blood pressure, and kidney function; (2) the pressure-natriuresis response using the mesenteric, celiac, and abdominal arterial occlusion technique; and (3) the natriuretic responses to acute saline expansion (0.9% NaCl, 10% body weight, intraperitoneal) or 2-week of 2% NaCl diet. Under basal conditions, PT- Nhe3^-/- mice showed significantly lower systolic, diastolic, and mean arterial blood pressure ( P<0.01) than WT mice ( P<0.01). PT- Nhe3^-/- mice also exhibited significantly greater diuretic ( P<0.01) and natriuretic responses than WT mice ( P<0.01), without altering 24-hour fecal Na⁺ excretion, plasma pH, Na⁺, and bicarbonate levels. In response to increased renal perfusion pressure by 30 mm Hg, the pressure-natriuresis response increased 5-fold in WT mice ( P<0.01), but it increased 8-fold in PT- Nhe3^-/- mice ( P<0.01). In response to 10% acute saline expansion or 2-week 2% NaCl diet, more pronounced natriuretic responses were demonstrated in PT- Nhe3^-/- than WT mice ( P<0.01). Our results support the scientific premise and physiological relevance that NHE3 in the proximal tubules plays an essential role in maintaining basal blood pressure homeostasis, and genetic deletion of NHE3 selectively in the proximal tubules of the kidney lowers blood pressure by increasing the pressure natriuretic response.

Chromatin Conformation Links Putative Enhancers in Intracranial Aneurysm-Associated Regions to Potential Candidate Genes

Background

We previously showed that intracranial aneurysm (IA)–associated single‐nucleotide polymorphisms are enriched in promoters and putative enhancers identified in the human circle of Willis, on which IAs develop, suggesting a role for promoters and enhancers in IAs. We further investigated the role of putative enhancers in the pathogenesis of IA by identifying their potential target genes and validating their regulatory activity.

Methods and Results

Using our previously published circle of Willis chromatin immunoprecipitation and sequencing data, we selected 34 putative enhancers in IA‐associated regions from genome‐wide association studies. We then used a chromatin conformation capture technique to prioritize target genes and found that 15 putative enhancers interact with the promoters of 6 target genes: SOX17,CDKN2B,MTAP,CNNM2,RPEL1, and GATA6. Subsequently, we assessed the activity of these putative enhancers in vivo in zebrafish embryos and confirmed activity for 8 putative enhancers. Last, we found that all 6 target genes are expressed in the circle of Willis, on the basis of RNA sequencing data and in situ hybridization. Furthermore, in situ hybridization showed that these genes are expressed in multiple cell types in the circle of Willis.

Conclusions

In 4 of 6 IA‐associated genome‐wide association study regions, we identified 8 putative enhancers that are active in vivo and interact with 6 nearby genes, suggesting that these genes are regulated by the identified putative enhancers. These genes, SOX17,CDKN2B,MTAP,CNNM2,RPEL1, and GATA6, are therefore potential candidate genes involved in IA pathogenesis and should be studied using animal models in the future.

Associations of the adrenomedullin gene polymorphism with prehypertension and hypertension in Lithuanian children and adolescents: a cross-sectional study

The aim of this study was to evaluate the association of ADM genetic variant and HBP among Lithuanian adolescents aged 12-15 years. This is a cross-sectional study of a randomly selected sample of 675 12-15-years-old schoolchildren who were surveyed during November 2010 to April 2012 in the baseline survey. Single-nucleotide polymorphism (SNP) of ADM gene (rs7129220) was evaluated using real-time PCR. Logistic regression analyses were used to test the associations of ADM (rs7129220) polymorphism with HBP under four inheritance models based on the Akaike Information Criterion (AIC) and to calculate the odds ratios. In the multivariate analysis, boys carrying ADM AG genotype (vs. carriers of ADM GG genotype), ADM AG + AA genotype (vs. carriers of ADM GG genotype) and ADM AG genotype (vs. carriers of ADM GG + AA genotype) had higher odds of having hypertension in codominant, dominant, and overdominant inheritance models. Girls with ADM AG + AA had increased odds of prehypertension compared to girls with the ADM GG genotype carriers in dominant inheritance model. Significant associations were observed in additive models separately for boys (hypertension) and girls (prehypertension). Our results indicate that ADM gene polymorphism was significantly associated with higher odds of HBP in Lithuanian adolescents aged 12-15 years.

Cardiometabolic Polygenic Risk Scores and Osteoarthritis Outcomes: A Mendelian Randomization Study Using Data From the Malmö Diet and Cancer Study and the UK Biobank

Objective

To investigate the causal role of cardiometabolic risk factors in osteoarthritis (OA) using associated genetic variants.

Methods

We studied 27,691 adults from the Malmö Diet and Cancer Study (MDCS) and replicated novel findings among 376,435 adults from the UK Biobank. Trait‐specific polygenic risk scores for low‐density lipoprotein (LDL) and high‐density lipoprotein (HDL) cholesterol levels, triglyceride levels, body mass index (BMI), fasting plasma glucose (FPG) levels, and systolic blood pressure (BP) were used to test the associations of genetically predicted elevations in each trait with incident OA diagnosis (n = 3,559), OA joint replacement (n = 2,780), or both (total OA; n = 4,226) in Mendelian randomization (MR) analyses in the MDCS, and with self‐reported and/or hospital‐diagnosed OA (n = 65,213) in the UK Biobank. Multivariable MR, MR‐Egger, and weighted median MR were used to adjust for potential pleiotropic biases.

Results

In the MDCS, genetically predicted elevation in LDL cholesterol level was associated with a lower risk of OA diagnosis (odds ratio [OR] 0.83 [95% confidence interval (95% CI) 0.73–0.95] per 1SD increase) and total OA (OR 0.87 [95% CI 0.78–0.98]), which was supported by multivariable MR for OA diagnosis (OR 0.84 [95% CI 0.75–0.95]) and total OA (0.87 [95% CI 0.78–0.97]), and by conventional 2‐sample MR for OA diagnosis (OR 0.86 [95% CI 0.75–0.98]). MR‐Egger indicated no pleiotropic bias. Genetically predicted elevation in BMI was associated with an increased risk of OA diagnosis (OR 1.65 [95% CI 1.14–2.41]), while MR‐Egger indicated pleiotropic bias and a larger association with OA diagnosis (OR 3.25 [1.26–8.39]), OA joint replacement (OR 3.81 [95% CI 1.39–10.4]), and total OA (OR 3.41 [95% CI 1.43–8.15]). No associations were observed between genetically predicted HDL cholesterol level, triglyceride level, FPG level, or systolic BP and OA outcomes. The associations with LDL cholesterol levels were replicated in the UK Biobank (OR 0.95 [95% CI 0.93–0.98]).

Conclusion

Our MR study provides evidence of a causal role of lower LDL cholesterol level and higher BMI in OA.

Completing the genetic spectrum influencing coronary artery disease: from germline to somatic variation

Genetic and environmental factors influence the development of coronary artery disease (CAD). Genetic analyses of families and the population continue to yield important fundamental insights for CAD. For the past four decades, CAD human genetic research focused largely on the study of germline genetic variation in CAD and its risk factors. The first genes associated with CAD were discovered using basic Mendelian principles and pedigree analysis. Mapping of the human genome and advancement in sequencing technology sparked further discovery of novel genetic associations through exome sequencing and genome wide association analysis in increasingly larger populations. While prior work implicated in situ DNA damage as a feature of atherosclerosis, more recently, somatic mutagenesis in and clonal expansion of haematopoietic stem cells was found to influence risk of CAD. Mutations observed for this condition, termed clonal haematopoiesis of indeterminate potential, frequently occur within epigenetic regulator genes (e.g. DNMT3A, TET2, ASXL1, etc.), which are also implicated in leukaemogenesis. Hypercholesterolaemic mice with Tet2 bone marrow deficiency are predisposed to the development of atherosclerosis that may be partly related to inflammatory cytokines. As the genetic basis of CAD expands from the germline to somatic genome, our fundamental understanding of CAD continues to evolve; these new discoveries represent new opportunities for risk prediction and prevention, and a new facet of cardio-oncology.

Caffeine and blood pressure: a critical review perspective

The WHO reported that high blood pressure (BP) is one of the primary causes of death worldwide. Hypertension (HPT) is a major risk factor for CVD and related diseases as well as for diseases, leading to a considerable increase in cardiovascular risk. Since BP response could also be influenced by caffeine, which is widely consumed with coffee and other items, it is important to define the possible effects associated with caffeine intake. The most recent findings aimed at clarifying the role of caffeine consumption on BP and HPT risk/incidence are conflicting and difficult to interpret. Therefore, in the present narrative review, we aimed to examine various methodological inaccuracies/aspects and factors that make studies difficult to be compared, in order to obtain a single consensus on the effects of caffeine intake on the risk of BP and HPT. We observed that this heterogeneity in results could be due to the presence of: (i) several variables affecting BP (such as age, sex, genetic and lifestyle aspects); (ii) different caffeine content of food and beverages; and (iii) caffeine metabolism. Moreover, different methodological aspects in the evaluation of daily dietary caffeine intake and in the BP measurement could add some other bias in the interpretation of results. Therefore, it is mandatory to consider all methodological aspects and confounding factors to generate a standardised methodology in order to increase cross-study consistency and minimise confounding effects of different variables on the relationship between BP response and HPT risk/incidence after caffeine intake.

Generality of genomic findings on blood pressure traits and its usefulness in precision medicine in diverse populations: A systematic review

Remarkable findings from genome-wide association studies (GWAS) on blood pressure (BP) traits have made new insights for developing precision medicine toward more effective screening measures. However, generality of GWAS findings in diverse populations is hampered by some technical limitations. There is no comprehensive study to evaluate source(s) of the non-generality of GWAS results on BP traits, so to fill the gap, this systematic review study was carried out. Using MeSH terms, 1545 records were detected through searching in five databases and 49 relevant full-text articles were included in our review. Overall, 749 unique variants were reported, of those, majority of variants have been detected in Europeans and were associated to systolic and diastolic BP traits. Frequency of genetic variants with same position was low in European and non-European populations (n = 38). However, more than 200 (>25%) single nucleotide polymorphisms were found on same loci or linkage disequilibrium blocks (r² ≥ 80%). Investigating for locus position and linkage disequilibrium of infrequent unique variants showed modest to high reproducibility of findings in Europeans that in some extent was generalizable in other populations. Beyond theoretical limitations, our study addressed other possible sources of non-generality of GWAS findings for BP traits in the same and different origins.

Genome-Wide Association Studies of Hypertension and Several Other Cardiovascular Diseases

Genome-wide association studies (GWAS) have greatly expanded our understanding of the genetic architecture of cardiovascular diseases in the past decade. They have revealed hundreds of suggestive genetic loci that replicate known biological candidate genes and indicate the existence of a previously unsuspected new biology relevant to cardiovascular disorders. These data have been used successfully to create genetic risk scores that may improve risk prediction and the identification of susceptive individuals. Furthermore, these GWAS-identified novel pathways may herald a new era of novel drug development and stratification of patients. In this review, we will briefly summarize the literature on the candidate genes and signals discovered by GWAS on hypertension and coronary artery disease and discuss their implications on clinical medicine.

Mechanisms of hypertension in autoimmune rheumatic diseases

Patients with autoimmune rheumatic diseases including rheumatoid arthritis and systemic lupus erythematosus have an increased prevalence of hypertension. There is now a large body of evidence showing that the immune system is a key mediator in both human primary hypertension and experimental models. Many of the proposed immunological mechanisms leading to primary hypertension are paralleled in autoimmune rheumatic disorders. Therefore, examining the link between autoimmunity and hypertension can be informative for understanding primary hypertension. This review examines the prevalent hypertension, the immune mediators that contribute to the prevalent hypertension and their impact on renal function and how the risk of hypertension is potentially influenced by common hormonal changes that are associated with autoimmune rheumatic diseases.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Dissecting features of epigenetic variants underlying cardiometabolic risk using full-resolution epigenome profiling in regulatory elements

Sparse profiling of CpG methylation in blood by microarrays has identified epigenetic links to common diseases. Here we apply methylC-capture sequencing (MCC-Seq) in a clinical population of ~200 adipose tissue and matched blood samples (Ntotal~400), providing high-resolution methylation profiling (>1.3 M CpGs) at regulatory elements. We link methylation to cardiometabolic risk through associations to circulating plasma lipid levels and identify lipid-associated CpGs with unique localization patterns in regulatory elements. We show distinct features of tissue-specific versus tissue-independent lipid-linked regulatory regions by contrasting with parallel assessments in ~800 independent adipose tissue and blood samples from the general population. We follow-up on adipose-specific regulatory regions under (1) genetic and (2) epigenetic (environmental) regulation via integrational studies. Overall, the comprehensive sequencing of regulatory element methylomes reveals a rich landscape of functional variants linked genetically as well as epigenetically to plasma lipid traits.

Epigenetic modification: a regulatory mechanism in essential hypertension

Essential hypertension (EH) is a multifactorial disease of the cardiovascular system that is influenced by the interplay of genetic, epigenetic, and environmental factors. The molecular dynamics underlying EH etiopathogenesis is unknown; however, earlier studies have revealed EH-associated genetic variants. Nevertheless, this finding alone is not sufficient to explain the variability in blood pressure, suggesting that other risk factors are involved, such as epigenetic modifications. Therefore, this review highlights the potential contribution of well-defined epigenetic mechanisms in EH, specifically, DNA methylation, post-translational histone modifications, and microRNAs. We further emphasize global and gene-specific DNA methylation as one of the most well-studied hallmarks among all epigenetic modifications in EH. In addition, post-translational histone modifications, such as methylation, acetylation, and phosphorylation, are described as important epigenetic markers associated with EH. Finally, we discuss microRNAs that affect blood pressure by regulating master genes such as those implicated in the renin-angiotensin-aldosterone system. These epigenetic modifications, which appear to contribute to various cardiovascular diseases, including EH, may be a promising research area for the development of novel future strategies for EH prevention and therapeutics.

Shared genes between Alzheimer's disease and ischemic stroke

Aims

Although converging evidence from experimental and epidemiological studies indicates Alzheimer's disease (AD) and ischemic stroke (IS) are related, the genetic basis underlying their links is less well characterized. Traditional SNP‐based genome‐wide association studies (GWAS) have failed to uncover shared susceptibility variants of AD and IS. Therefore, this study was designed to investigate whether pleiotropic genes existed between AD and IS to account for their phenotypic association, although this was not reported in previous studies.

Methods

Taking advantage of large‐scale GWAS summary statistics of AD (17,008 AD cases and 37,154 controls) and IS (10,307 IS cases and 19,326 controls), we performed gene‐based analysis implemented in VEGAS2 and Fisher's meta‐analysis of the set of overlapped genes of nominal significance in both diseases. Subsequently, gene expression analysis in AD‐ or IS‐associated expression datasets was conducted to explore the transcriptional alterations of pleiotropic genes identified.

Results

16 AD‐IS pleiotropic genes surpassed the cutoff for Bonferroni‐corrected significance. Notably, MS4A4A and TREM2, two established AD‐susceptibility genes showed remarkable alterations in the spleens and brains afflicted by IS, respectively. Among the prioritized genes identified by virtue of literature‐based knowledge, most are immune‐relevant genes (EPHA1, MS4A4A, UBE2L3 and TREM2), implicating crucial roles of the immune system in the pathogenesis of AD and IS.

Conclusions

The observation that AD and IS had shared disease‐associated genes offered mechanistic insights into their common pathogenesis, predominantly involving the immune system. More importantly, our findings have important implications for future research directions, which are encouraged to verify the involvement of these candidates in AD and IS and interpret the exact molecular mechanisms of action.

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 Implications of Natriuretic Peptides in the Protection from Hypertension and Target Organ Damage Development

The pathogenesis of hypertension, as a multifactorial trait, is complex. High blood pressure levels, in turn, concur with the development of cardiovascular damage. Abnormalities of several neurohormonal mechanisms controlling blood pressure homeostasis and cardiovascular remodeling can contribute to these pathological conditions. The natriuretic peptide (NP) family (including ANP (atrial natriuretic peptide), BNP (brain natriuretic peptide), and CNP (C-type natriuretic peptide)), the NP receptors (NPRA, NPRB, and NPRC), and the related protease convertases (furin, corin, and PCSK6) constitute the NP system and represent relevant protective mechanisms toward the development of hypertension and associated conditions, such as atherosclerosis, stroke, myocardial infarction, heart failure, and renal injury. Initially, several experimental studies performed in different animal models demonstrated a key role of the NP system in the development of hypertension. Importantly, these studies provided relevant insights for a better comprehension of the pathogenesis of hypertension and related cardiovascular phenotypes in humans. Thus, investigation of the role of NPs in hypertension offers an excellent example in translational medicine. In this review article, we will summarize the most compelling evidence regarding the molecular mechanisms underlying the physiological and pathological impact of NPs on blood pressure regulation and on hypertension development. We will also discuss the protective effect of NPs toward the increased susceptibility to hypertensive target organ damage.

Aspalathus linearis (Rooibos) - a functional food targeting cardiovascular disease

Increasing consumer bias toward natural products and the considerable wealth of indigenous knowledge has precipitated an upturn in market-driven research into potentially beneficial medicinal plants. In this context, Aspalathus linearis (Rooibos) has been identified to be a promising candidate which may impact cardiovascular disease (CVD), which is one of the most widely studied chronic diseases of modern times. Despite these efforts, ischemic heart disease remains the number one cause of mortality globally. Apart from genetic predisposition and other aetiological mechanisms specific to particular types of CVD, co-factors from interlinked systems contribute significantly to disease development and the severity of its clinical manifestation. The bioactivity of Rooibos is directed towards multiple therapeutic targets. Experimental data to date include antioxidant, anti-inflammatory and anti-diabetic effects, as well as modulatory effects in terms of the immune system, adrenal steroidogenesis and lipid metabolism. This review integrates relevant literature on the therapeutic potential of Rooibos in the context of CVD, which is currently the most common of non-communicable diseases. The therapeutic value of whole plant extracts versus isolated active ingredients are addressed, together with the potential for overdose or herb-drug interaction. The body of research undertaken to date clearly underlines the benefits of Rooibos as both preventative and complementary therapeutic functional food in the context of CVD.

Genome-wide association study of body fat distribution identifies adiposity loci and sex-specific genetic effects

Body mass and body fat composition are of clinical interest due to their links to cardiovascular- and metabolic diseases. Fat stored in the trunk has been suggested to be more pathogenic compared to fat stored in other compartments. In this study, we perform genome-wide association studies (GWAS) for the proportion of body fat distributed to the arms, legs and trunk estimated from segmental bio-electrical impedance analysis (sBIA) for 362,499 individuals from the UK Biobank. 98 independent associations with body fat distribution are identified, 29 that have not previously been associated with anthropometric traits. A high degree of sex-heterogeneity is observed and the effects of 37 associated variants are stronger in females compared to males. Our findings also implicate that body fat distribution in females involves mesenchyme derived tissues and cell types, female endocrine tissues as well as extracellular matrix maintenance and remodeling.

Obesity and the distribution of fat within the body are risk factors for cardiometabolic diseases. Here, Rask-Andersen et al. perform GWAS for bio-electrical impedance measurements in UK Biobank participants and identify 29 novel independent loci for fat distribution and a high degree of sex-heterogeneity.

A genetic risk score for hypertension is associated with risk of thoracic aortic aneurysm

A genetic risk score (GRS) based on 29 single nucleotide polymorpysms (SNPs) associated with high blood pressure (BP) was prospectively associated with development of hypertension, stroke and cardiovascular events. The aim of the present study was to evaluate the impact of this GRS on the incidence of aortic disease, including aortic dissection (AD), rupture or surgery of a thoracic (TAA) or abdominal (AAA) aortic aneurysm. More than 25,000 people from the Swedish Malmo Diet and Cancer Study had information on at least 24 SNPs and were followed up for a median ≥ 18 years. The number of BP elevating alleles of each SNPs, weighted by their effect size in the discovery studies, was summed into a BP-GRS. In Cox regression models, adjusted for traditional cardiovascular risk factors including hypertension, we found significant associations of the BP-GRS, prospectively, with incident TAA (hazard ratio (HR) 1.64 (95% confidence interval (CI) 1.081-2.475 comparing the third vs. the first tertile; p = 0.020) but not with either AAA or aortic dissection. Calibration, discrimination and reclassification analyses show modest improvement in prediction using the BP-GRS in addition to the model which used only traditional risk factors. A GRS for hypertension associates with TAA suggesting a link between genetic determinants of BP and aortic disease. The effect size is small but the addition of more SNPs to the GRS might improve its discriminatory capability.

Trans-ethnic association study of blood pressure determinants in over 750,000 individuals

In this trans-ethnic multi-omic study, we reinterpret the genetic architecture of blood pressure to identify genes, tissues, phenomes and medication contexts of blood pressure homeostasis. We discovered 208 novel common blood pressure SNPs and 53 rare variants in genome-wide association studies of systolic, diastolic and pulse pressure in up to 776,078 participants from the Million Veteran Program (MVP) and collaborating studies, with analysis of the blood pressure clinical phenome in MVP. Our transcriptome-wide association study detected 4,043 blood pressure associations with genetically predicted gene expression of 840 genes in 45 tissues, and mouse renal single-cell RNA sequencing identified upregulated blood pressure genes in kidney tubule cells.

Gene-gene interactions and associations of six hypertension related single nucleotide polymorphisms with obesity risk in a Chinese children population

Obesity is a major risk for hypertension. However, the associations between hypertension susceptibility loci and the risk of obesity as well as the effects of gene-gene interactions are unclear, especially in the Chinese children population. Six single nucleotide polymorphisms (SNPs) (ATP2B1 rs17249754, CSK rs1378942, MTHFR rs1801133, CYP17A1 rs1004467, STK39 rs3754777, FGF5 rs16998073) were genotyped for 3503 Chinese children, aged 6-18 years. Of them, 758 obese cases and 2745 controls were identified based on the International Obesity Task Force age- and sex-specific BMI references. Among the six SNPs, three were associated with obesity risk (CSK rs1378942: odds ratio (OR) = 1.20, 95% confidence interval (CI) 1.01-1.43, P = 0.042; MTHFR rs1801133: OR = 1.19, 95% CI 1.05-1.34, P = 0.006; FGF5 rs16998073: OR = 1.14, 95% CI 1.00-1.29, P = 0.047). The genetic risk score (GRS), based on these three SNPs (CSK rs1378942, MTHFR rs1801133, FGF5 rs16998073), showed a positive association with risk of obesity (OR = 1.18, 95% CI 1.09-1.28, P = 7.60 × 10-5). The same association signals were also detected in the subgroups of puberty and inactivity. In addition, interaction analyses among these loci implied a potential gene-gene interaction between MTHFR and FGF5. These findings show a significant association of hypertension susceptibility loci in Chinese children, suggesting a likely influence of genetic and environmental factors on the risk of obesity.

Expanding the clinical relevance of the 5'-nucleotidase cN-II/NT5C2

Purine metabolism is depending on a large amount of enzymes to ensure cellular homeostasis. Among these enzymes, we have been interested in the 5'-nucleotidase cN-II and its role in cancer biology and in response of cancer cells to treatments. This protein has been cited and studied in a large number of papers published during the last decade for its involvement in non-cancerous pathologies such as hereditary spastic paraplegia, schizophrenia, and blood pressure regulation. Here, we review these articles in order to give an overview of the recently discovered clinical relevance of cN-II.

Interethnic analyses of blood pressure loci in populations of East Asian and European descent

Blood pressure (BP) is a major risk factor for cardiovascular disease and more than 200 genetic loci associated with BP are known. Here, we perform a multi-stage genome-wide association study for BP (max N = 289,038) principally in East Asians and meta-analysis in East Asians and Europeans. We report 19 new genetic loci and ancestry-specific BP variants, conforming to a common ancestry-specific variant association model. At 10 unique loci, distinct non-rare ancestry-specific variants colocalize within the same linkage disequilibrium block despite the significantly discordant effects for the proxy shared variants between the ethnic groups. The genome-wide transethnic correlation of causal-variant effect-sizes is 0.898 and 0.851 for systolic and diastolic BP, respectively. Some of the ancestry-specific association signals are also influenced by a selective sweep. Our results provide new evidence for the role of common ancestry-specific variants and natural selection in ethnic differences in complex traits such as BP.

Blood pressure (BP) is a major risk factor for cardiovascular disease and more than 200 genetic loci associated with BP are known. Here, the authors perform discovery GWAS for BP in East Asians and meta-analysis in East Asians and Europeans and report ancestry-specific BP SNPs and selection signals.

Maternal corticotropin-releasing hormone is associated with LEP DNA methylation at birth and in childhood: an epigenome-wide study in Project Viva

Background:

Corticotropin-releasing hormone (CRH) plays a central role in regulating the secretion of cortisol which controls a wide range of biological processes. Fetuses overexposed to cortisol have increased risks of disease in later life. DNA methylation may be the underlying association between prenatal cortisol exposure and health effects. We investigated associations between maternal CRH levels and epigenome-wide DNA methylation of cord blood in offsprings and evaluated whether these associations persisted into mid-childhood.

Methods:

We investigated mother-child pairs enrolled in the prospective Project Viva pre-birth cohort. We measured DNA methylation in 257 umbilical cord blood samples using the HumanMethylation450 Bead Chip. We tested associations of maternal CRH concentration with cord blood cells DNA methylation, adjusting the model for maternal age at enrollment, education, maternal race/ethnicity, pre-pregnancy body mass index, parity, gestational age at delivery, child sex, and cell-type composition in cord blood. We further examined the persistence of associations between maternal CRH levels and DNA methylation in children’s blood cells collected at mid-childhood (N = 239, age: 6.7–10.3 years) additionally adjusting for the children’s age at blood drawn.

Results:

Maternal CRH levels are associated with DNA methylation variability in cord blood cells at 96 individual CpG sites (False Discovery Rate < 0.05). Among the 96 CpG sites, we identified 3 CpGs located near the LEP gene. Regional analyses confirmed the association between maternal CRH and DNA methylation near LEP. Moreover, higher maternal CRH levels were associated with higher blood-cell DNA methylation of the promoter region of LEP in mid-childhood (P < 0.05, β = 0.64, SE = 0.30).

Conclusion:

In our cohort, maternal CRH was associated with DNA methylation levels in newborns at multiple loci, notably in the LEP gene promoter. The association between maternal CRH and LEP DNA methylation levels persisted into mid-childhood.

Uncovering association networks through an eQTL analysis involving human miRNAs and lincRNAs

Non-coding RNAs (ncRNA) have an essential role in the complex landscape of human genetic regulatory networks. One area that is poorly explored is the effect of genetic variations on the interaction between ncRNA and their targets. By integrating a significant amount of public data, the present study cataloged the vast landscape of the regulatory effect of microRNAs (miRNA) and long intergenic noncoding RNAs (lincRNA) in the human genome. An expression quantitative trait loci (eQTL) analysis was used to identify genetic variants associated with miRNA and lincRNA and whose genotypes affect gene expression. Association networks were built for eQTL associated to traits of clinical and/or pharmacological relevance.

Combined linkage and association analysis identifies rare and low frequency variants for blood pressure at 1q31

High blood pressure (BP) is a major risk factor for cardiovascular disease (CVD) and is more prevalent in African Americans as compared to other US groups. Although large, population-based genome-wide association studies (GWAS) have identified over 300 common polymorphisms modulating inter-individual BP variation, largely in European ancestry subjects, most of them do not localize to regions previously identified through family-based linkage studies. This discrepancy has remained unexplained despite the statistical power differences between current GWAS and prior linkage studies. To address this issue, we performed genome-wide linkage analysis of BP traits in African-American families from the Family Blood Pressure Program (FBPP) and genotyped on the Illumina Human Exome BeadChip v1.1. We identified a genomic region on chromosome 1q31 with LOD score 3.8 for pulse pressure (PP), a region we previously implicated in DBP studies of European ancestry families. Although no reported GWAS variants map to this region, combined linkage and association analysis of PP identified 81 rare and low frequency exonic variants accounting for the linkage evidence. Replication analysis in eight independent African ancestry cohorts (N = 16,968) supports this specific association with PP (P = 0.0509). Additional association and network analyses identified multiple potential candidate genes in this region expressed in multiple tissues and with a strong biological support for a role in BP. In conclusion, multiple genes and rare variants on 1q31 contribute to PP variation. Beyond producing new insights into PP, we demonstrate how family-based linkage and association studies can implicate specific rare and low frequency variants for complex traits.

Identification of 13 novel susceptibility loci for early-onset myocardial infarction, hypertension, or chronic kidney disease

Early-onset cardiovascular and renal diseases have a strong genetic component. In the present study, exome-wide association studies (EWASs) were performed to identify genetic variants that confer susceptibility to early-onset myocardial infarction (MI), hypertension, or chronic kidney disease (CKD) in Japanese individuals. A total of 8,093 individuals aged ≤65 years was enrolled in the study. The EWASs for MI, hypertension, and CKD were performed in 6,926 subjects (1,152 cases, 5,774 controls), 8,080 subjects (3,444 cases, 4,636 controls), and 2,556 subjects (1,051 cases, 1,505 controls), respectively. Genotyping of single nucleotide polymorphisms (SNPs) was performed with Illumina Human Exome-12 DNA Analysis BeadChip or Infinium Exome-24 BeadChip arrays. The associations of allele frequencies for 31,245, 31,276, or 31,514 SNPs that passed quality control to MI, hypertension, and CKD, respectively, was examined with Fisher's exact test. Bonferroni's correction for statistical significance of association was applied to compensate for multiple comparisons of genotypes with MI, hypertension, or CKD. The EWASs of allele frequencies revealed that 25, 11, and 11 SNPs were significantly associated with MI (P<1.60×10⁻⁶), hypertension (P<1.60×10⁻⁶), or CKD (P<1.59×10⁻⁶), respectively. Multivariable logistic regression analysis with adjustment for covariates showed that all 25, 11, and 11 SNPs were significantly associated with MI (P<0.0005), hypertension (P<0.0011), or CKD (P<0.0011), respectively. On examination of the results from previous genome-wide association studies and linkage disequilibrium of the identified SNPs, 11 loci (TMOD4, COL6A3, ADGRL3-CXCL8-MARCH1, OR52E4, TCHP-GIT2, CCDC63, 12q24.1, OAS3, PLCB2-VPS33B, GOSR2, ZNF77), six loci (MOB3C-TMOD4, COL6A3, COL6A5, CXCL8-MARCH1, NFKBIL1-6p21.3-NCR3, PLCB2-VPS33B), and seven loci (MOB3C-TMOD4, COL6A3, COL6A5, ADGRL3-CXCL8-MARCH1, MUC17, PLCB2-VPS33B, ZNF77) were identified as novel loci significantly associated with MI, hypertension, and CKD, respectively. Furthermore, six genes (TMOD4, COL6A3, CXCL8, MARCH1, PLCB2, VPS33B) were significantly associated with MI, hypertension and CKD; two genes (ADGRL3, ZNF77) with MI and CKD; and two genes (COL6A5, MOB3C) with hypertension and CKD. Therefore, 13 novel loci (MOB3C-TMOD4, COL6A3, ADGRL3-CXCL8-MARCH1, OR52E4, TCHP- GIT2, CCDC63, 12q24.1, OAS3, PLCB2-VPS33B, ZNF77, COL6A5, NFKBIL1-NCR3, MUC17) were identified that confer susceptibility to early-onset MI, hypertension, or CKD. The determination of genotypes for the SNPs at these loci may provide informative for assessment of the genetic risk for MI, hypertension, or CKD.

MECHANISMS IN ENDOCRINOLOGY: Rare defects in adrenal steroidogenesis

Congenital adrenal hyperplasia (CAH) is a group of genetic disorders of adrenal steroidogenesis that impair cortisol synthesis, with compensatory increases in ACTH leading to hyperplastic adrenals. The term 'CAH' is generally used to mean 'steroid 21-hydroxylase deficiency' (21OHD) as 21OHD accounts for about 95% of CAH in most populations; the incidences of the rare forms of CAH vary with ethnicity and geography. These forms of CAH are easily understood on the basis of the biochemistry of steroidogenesis. Defects in the steroidogenic acute regulatory protein, StAR, disrupt all steroidogenesis and are the second-most common form of CAH in Japan and Korea; very rare defects in the cholesterol side-chain cleavage enzyme, P450scc, are clinically indistinguishable from StAR defects. Defects in 3β-hydroxysteroid dehydrogenase, which also causes disordered sexual development, were once thought to be fairly common, but genetic analyses show that steroid measurements are generally unreliable for this disorder. Defects in 17-hydroxylase/17,20-lyase ablate synthesis of sex steroids and also cause mineralocorticoid hypertension; these are common in Brazil and in China. Isolated 17,20-lyase deficiency can be caused by rare mutations in at least three different proteins. P450 oxidoreductase (POR) is a co-factor used by 21-hydroxylase, 17-hydroxylase/17,20-lyase and aromatase; various POR defects, found in different populations, affect these enzymes differently. 11-Hydroxylase deficiency is the second-most common form of CAH in European populations but the retention of aldosterone synthesis distinguishes it from 21OHD. Aldosterone synthase deficiency is a rare salt-losing disorder. Mild, 'non-classic' defects in all of these factors have been described. Both the severe and non-classic disorders can be treated if recognized.

Golgin-97 Targets Ectopically Expressed Inward Rectifying Potassium Channel, Kir2.1, to the trans-Golgi Network in COS-7 Cells

The inward rectifying potassium channel, Kir2.1, is selected as cargo at the trans-Golgi network (TGN) for export to the cell surface through a unique signal-dependent interaction with the AP1 clathrin-adaptor, but it is unknown how the channel is targeted at earlier stages in the secretory pathway for traffic to the TGN. Here we explore a mechanism. A systematic screen of Golgi tethers identified Golgin-97 as a Kir2.1 binding partner. In vitro protein-interaction studies revealed the interaction is direct, occurring between the GRIP domain of Golgin-97 and the cytoplasmic domain of Kir2.1. Imaging and interaction studies in COS-7 cells suggest that Golgi-97 binds to the channel en route through the Golgi. RNA interference-mediated knockdown of Golgin-97 prevented exit of Kir2.1 from the Golgi. These observations identify Golgin-97 as a Kir2.1 binding partner that is required for targeting the channel to the TGN. Based on our studies in COS-7 cells, we propose Golgi-97 facilitates formation of AP1-dependent export carriers for Kir2.1 by coupling anterograde delivery of Kir2.1 with retrograde recycling of AP-1 containing endosomes to the TGN.

Non-coding RNAs in cardiovascular diseases: diagnostic and therapeutic perspectives

Recent research has demonstrated that the non-coding genome plays a key role in genetic programming and gene regulation during development as well as in health and cardiovascular disease. About 99% of the human genome do not encode proteins, but are transcriptionally active representing a broad spectrum of non-coding RNAs (ncRNAs) with important regulatory and structural functions. Non-coding RNAs have been identified as critical novel regulators of cardiovascular risk factors and cell functions and are thus important candidates to improve diagnostics and prognosis assessment. Beyond this, ncRNAs are rapidly emgerging as fundamentally novel therapeutics. On a first level, ncRNAs provide novel therapeutic targets some of which are entering assessment in clinical trials. On a second level, new therapeutic tools were developed from endogenous ncRNAs serving as blueprints. Particularly advanced is the development of RNA interference (RNAi) drugs which use recently discovered pathways of endogenous short interfering RNAs and are becoming versatile tools for efficient silencing of protein expression. Pioneering clinical studies include RNAi drugs targeting liver synthesis of PCSK9 resulting in highly significant lowering of LDL cholesterol or targeting liver transthyretin (TTR) synthesis for treatment of cardiac TTR amyloidosis. Further novel drugs mimicking actions of endogenous ncRNAs may arise from exploitation of molecular interactions not accessible to conventional pharmacology. We provide an update on recent developments and perspectives for diagnostic and therapeutic use of ncRNAs in cardiovascular diseases, including atherosclerosis/coronary disease, post-myocardial infarction remodelling, and heart failure.

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.

Testing an optimally weighted combination of common and/or rare variants with multiple traits

Recently, joint analysis of multiple traits has become popular because it can increase statistical power to identify genetic variants associated with complex diseases. In addition, there is increasing evidence indicating that pleiotropy is a widespread phenomenon in complex diseases. Currently, most of existing methods test the association between multiple traits and a single genetic variant. However, these methods by analyzing one variant at a time may not be ideal for rare variant association studies because of the allelic heterogeneity as well as the extreme rarity of rare variants. In this article, we developed a statistical method by testing an optimally weighted combination of variants with multiple traits (TOWmuT) to test the association between multiple traits and a weighted combination of variants (rare and/or common) in a genomic region. TOWmuT is robust to the directions of effects of causal variants and is applicable to different types of traits. Using extensive simulation studies, we compared the performance of TOWmuT with the following five existing methods: gene association with multiple traits (GAMuT), multiple sequence kernel association test (MSKAT), adaptive weighting reverse regression (AWRR), single-TOW, and MANOVA. Our results showed that, in all of the simulation scenarios, TOWmuT has correct type I error rates and is consistently more powerful than the other five tests. We also illustrated the usefulness of TOWmuT by analyzing a whole-genome genotyping data from a lung function study.

Association between ATP2B1 and CACNB2 polymorphisms and high blood pressure in a population of Lithuanian children and adolescents: a cross-sectional study

OBJECTIVES

Recently, genome-wide associated studies have identified several genetic loci that are associated with elevated blood pressure and could play a critical role in intracellular calcium homeostasis. The aim of this study was to assess the associations of ATP2B1 rs2681472 and CACNB2 rs12258967 gene polymorphisms with high blood pressure (HBP) among Lithuanian children and adolescents aged 12-15 years.

STUDY DESIGN AND PARTICIPANTS

This was a cross-sectional study of a randomly selected sample of 646 12-15-year-old adolescents who participated in the survey 'The Prevalence and Risk Factors of HBP in 12-15 Year-Old Lithuanian Children and Adolescents (from November 2010 to April 2012)'. Anthropometric parameters and BP were measured. The participants with HBP were screened on two separate occasions. Subjects were genotyped ATP2B1 rs2681472 and CACNB2 rs12258967 gene polymorphisms using real-time PCR method.

RESULTS

The prevalence of HBP was 36.7%, significantly higher for boys than for girls. In the multivariate analysis, after adjustment for body mass index and waist circumference, boys with CACNB2 CG genotype, CACNB2 GG genotype and CACNB2 CG +GG genotype had higher odds of having HBP in codominant (adjusted OR (aOR)=1.92; 95% CI 1.16 to 3.18, p=0.011; and aOR=2.64; 95% CI 1.19 to 5.90, p=0.018) and in dominant (aOR=2.05; 95% CI 1.27 to 3.30, p=0.003) inheritance models. Girls carrying CACNB2 CG genotype and CACNB2 CG +GG genotype had increased odds of HBP in codominant (aOR=1.82; 95% CI 1.02 to 3.24, p=0.044) and in dominant (aOR=1.89; 95% CI 1.09 to 3.28, p=0.023) inheritance models. Furthermore, significant associations were found in additive models separately for boys (aOR=1.72; 95% CI 1.20 to 2.46, p=0.003) and girls (aOR=1.52; 95% CI 1.05 to 2.20, p=0.027). No significant association was found between ATP2B1 gene polymorphism and the odds of HBP.

CONCLUSIONS

Our results indicate that CACNB2 gene polymorphism was significantly associated with higher odds of HBP in Lithuanian adolescents aged 12-15 years.

Association between ApoE polymorphism and hypertension: A meta-analysis of 28 studies including 5898 cases and 7518 controls

Hypertension is one of the most common chronic diseases, constituting an independent risk factor for many diseases. Our study aimed to evaluate the association between apolipoprotein E (ApoE) genetic polymorphism and hypertension, and to provide evidence for the etiology of hypertension. Case-control studies of ApoE polymorphism and hypertension, which were included in PubMed, Embase, Web of Science, Medline, WanFang, Vip, and CNKI information databases, were selected and evaluated according to criteria of inclusion and exclusion. Eligible data were extracted and pooled, and were analyzed and assessed using Stata 12.0. Random-effect models were used when heterogeneity existed in between-study, and fixed-effect models were applied otherwise. A total of 28 studies that consisted of 5898 cases with hypertension and 7518 controls were selected. Alleles and genotypes of ApoE between cases and controls were compared. For ApoE alleles, we observed the contrast of ApoE ε2 versus ε3 allele yielded a pooled OR of 0.99 (95% CI: 0.87-1.11; P = 0.823), whereas the contrast of ε4 versus ε3 allele yielded a pooled OR of 1.95 (95% CI: 1.50-2.54; P < 0.001). For ApoE genotypes, compared with ε3/ε3 genotype, genotypes (ε2/ε2 and ε2/ε3) showed a possible association with hypertension (OR = 0.88; 95% CI: 0.79-0.99; P = 0.033), and genotypes (ε3/ε4 and ε4/ε4) had a 2.08-fold risk of developing hypertension (OR = 2.08; 95% CI: 1.58-2.74; P < 0.001). There is the association between ApoE polymorphism and hypertension: the genotypes carrying ε2 allele may be a protective factor, and the ApoE ε4 allele and the genotypes carrying ε4 allele may be risk factors for hypertension.

MR-PheWAS: exploring the causal effect of SUA level on multiple disease outcomes by using genetic instruments in UK Biobank

OBJECTIVES

We aimed to investigate the role of serum uric acid (SUA) level in a broad spectrum of disease outcomes using data for 120 091 individuals from UK Biobank.

METHODS

We performed a phenome-wide association study (PheWAS) to identify disease outcomes associated with SUA genetic risk loci. We then implemented conventional Mendelianrandomisation (MR) analysis to investigate the causal relevance between SUA level and disease outcomes identified from PheWAS. We next applied MR Egger analysis to detect and account for potential pleiotropy, which conventional MR analysis might mistake for causality, and used the HEIDI (heterogeneity in dependent instruments) test to remove cross-phenotype associations that were likely due to genetic linkage.

RESULTS

Our PheWAS identified 25 disease groups/outcomes associated with SUA genetic risk loci after multiple testing correction (P<8.57e-05). Our conventional MR analysis implicated a causal role of SUA level in three disease groups: inflammatory polyarthropathies (OR=1.22, 95% CI 1.11 to 1.34), hypertensive disease (OR=1.08, 95% CI 1.03 to 1.14) and disorders of metabolism (OR=1.07, 95% CI 1.01 to 1.14); and four disease outcomes: gout (OR=4.88, 95% CI 3.91 to 6.09), essential hypertension (OR=1.08, 95% CI 1.03 to 1.14), myocardial infarction (OR=1.16, 95% CI 1.03 to 1.30) and coeliac disease (OR=1.41, 95% CI 1.05 to 1.89). After balancing pleiotropic effects in MR Egger analysis, only gout and its encompassing disease group of inflammatory polyarthropathies were considered to be causally associated with SUA level. Our analysis highlighted a locus (ATXN2/S2HB3) that may influence SUA level and multiple cardiovascular and autoimmune diseases via pleiotropy.

CONCLUSIONS

Elevated SUA level is convincing to cause gout and inflammatory polyarthropathies, and might act as a marker for the wider range of diseases with which it associates. Our findings support further investigation on the clinical relevance of SUA level with cardiovascular, metabolic, autoimmune and respiratory diseases.

Characteristics and treatment of African-American and European-American patients with resistant hypertension identified using the electronic health record in an academic health centre: a case-control study

OBJECTIVE

To identify patients with hypertension with resistant and controlled blood pressure (BP) using electronic health records (EHRs) in order to elucidate practices in the real-world clinical treatment of hypertension and to enable future genetic studies.

DESIGN

Using EHRs, we developed and validated algorithms to identify patients with resistant and controlled hypertension.

SETTING

An academic medical centre in Nashville, Tennessee.

POPULATION

European-American (EA) and African-American (AA) patients with hypertension.

MAIN OUTCOME MEASURES

Demographic characteristics: race, age, gender, body mass index, outpatient BPs and the history of diabetes mellitus, chronic kidney disease stage 3, ischaemic heart disease, transient ischaemic attack, atrial fibrillation and sleep apnoea.

MEDICATION TREATMENT

All antihypertensive medication classes prescribed to a patient at the time of classification and ever prescribed following classification.

RESULTS

The algorithms had performance metrics exceeding 92%. The prevalence of resistant hypertension in the total hypertensive population was 7.3% in EA and 10.5% in AA. At diagnosis, AA were younger, heavier, more often female and had a higher incidence of type 2 diabetes and higher BPs than EA. AA with resistant hypertension were more likely to be treated with vasodilators, dihydropyridine calcium channel blockers and alpha-2 agonists while EA were more likely to be treated with angiotensin receptor blockers, renin inhibitors and beta blockers. Mineralocorticoid receptor antagonists use was increased in patients treated with more than four antihypertensive medications compared with patients treated with three (12.4% vs 2.6% in EA, p<0.001; 12.3% vs 2.8% in AA, p<0.001). The number of patients treated with a mineralocorticoid receptor antagonist increased to 37.4% in EA and 41.2% in AA over a mean follow-up period of 7.4 and 8.7 years, respectively.

CONCLUSIONS

Clinical treatment of resistant hypertension differs in EA and AA patients. These results demonstrate the feasibility of identifying resistant hypertension using an EHR.

Scientific Contributions of Population-Based Studies to Cardiovascular Epidemiology in the GWAS Era

Longitudinal, well phenotyped, population-based cohort studies offer unique research opportunities in the context of genome-wide association studies (GWAS), including GWAS for new-onset (incident) cardiovascular disease (CVD) events, the assessment of gene x lifestyle interactions, and evaluating the incremental predictive utility of genetic information in apparently healthy individuals. Furthermore, comprehensively phenotyped community-dwelling samples have contributed to GWAS of numerous traits that reflect normal organ function (e.g., cardiac structure and systolic and diastolic function) and for many traits along the CVD continuum (e.g., risk factors, circulating biomarkers, and subclinical disease traits). These GWAS have heretofore identified many genetic loci implicated in normal organ function and different stages of the CVD continuum. Finally, population-based cohort studies have made important contributions to Mendelian Randomization analyses, a statistical approach that uses genetic information to assess observed associations between cardiovascular traits and clinical CVD outcomes for potential causality.

Molecular genetic contributions to self-rated health

Background: Poorer self-rated health (SRH) predicts worse health outcomes, even when adjusted for objective measures of disease at time of rating. Twin studies indicate SRH has a heritability of up to 60% and that its genetic architecture may overlap with that of personality and cognition.

Methods: We carried out a genome-wide association study (GWAS) of SRH on 111 749 members of the UK Biobank sample. Univariate genome-wide complex trait analysis (GCTA)-GREML analyses were used to estimate the proportion of variance explained by all common autosomal single nucleotide polymorphisms (SNPs) for SRH. Linkage disequilibrium (LD) score regression and polygenic risk scoring, two complementary methods, were used to investigate pleiotropy between SRH in the UK Biobank and up to 21 health-related and personality and cognitive traits from published GWAS consortia.

Results: The GWAS identified 13 independent signals associated with SRH, including several in regions previously associated with diseases or disease-related traits. The strongest signal was on chromosome 2 (rs2360675, P = 1.77 x 10^-10) close to KLF7. A second strong peak was identified on chromosome 6 in the major histocompatibility region (rs76380179, P = 6.15 x 10^-10). The proportion of variance in SRH that was explained by all common genetic variants was 13%. Polygenic scores for the following traits and disorders were associated with SRH: cognitive ability, education, neuroticism, body mass index (BMI), longevity, attention-deficit hyperactivity disorder (ADHD), major depressive disorder, schizophrenia, lung function, blood pressure, coronary artery disease, large vessel disease stroke and type 2 diabetes.

Conclusions: Individual differences in how people respond to a single item on SRH are partly explained by their genetic propensity to many common psychiatric and physical disorders and psychological traits.

What Is the Ideal Starting Point for an Olecranon Screw? An Anatomic Cadaveric Study

OBJECTIVE

To assess whether "center-center" position is ideal starting point for minimum fracture displacement when placing an intramedullary (IM) screw in the ulna.

METHODS

Thirty-six arms (average age, 82 years) underwent a posterior approach to the olecranon and were randomized into 3 groups: center-center (center in sagittal plane, center in coronal plane), posterior-lateral (posterior in sagittal plane, lateral in coronal plane), and posterior-medial (posterior in sagittal plane, medial in coronal plane). Groups were matched into 18 pairs, and fixation was performed with an IM screw. Primary outcome measure was articular surface displacement on the olecranon. Measurements were compared across each combination of locations using the Kruskal-Wallis rank sums test, and a sign test determined whether each location differed from anatomic reduction.

RESULTS

Articular step-off measurements were significantly different between center-center (0.6 mm) and posterior-medial (2.1 mm) groups (P = 0.01) and approached significance with posterior-lateral versus posterior-medial (0.9 mm) locations (P = 0.07). No significant difference was found comparing center-center with posterior-lateral locations (P = 0.7). The articular surface (P = 0.04), posterior cortex (P = 0.02), and medial cortex (P = 0.001) measurements for the posterior-medial starting point were all worse compared with anatomic reduction.

CONCLUSIONS

Malreduction of a simulated olecranon fracture was most significant when the starting point for the IM screw was malpositioned medially. A central or laterally based starting point was more forgiving. Avoiding a medially based starting point is crucial for achieving benefits of fixation with an IM screw and reduces the chance of malreduction after fixation.

A Review on Adducin from Functional to Pathological Mechanisms: Future Direction in Cancer

Adducin (ADD) is a family of membrane skeleton proteins including ADD1, ADD2, and ADD3 that are encoded by distinct genes on different chromosomes. Adducin is primarily responsible for the assembly of spectrin-actin network that provides physical support to the plasma membrane and mediates signal transduction in various cellular physiological processes upon regulation by protein kinase C-dependent and calcium/calmodulin-dependent pathways. Abnormal phosphorylation, genetic variations, and alternative splicing of adducin may contribute to alterations in cellular functions involved in pathogenic processes. These alterations are associated with a wide range of diseases including cancer. This paper begins with a discussion on how adducin partakes in the structural formation of membrane skeleton, its regulation, and related functional characteristics, followed by a review on the pathogenesis of hypertension, biliary atresia, and cancer with respect to increased disease susceptibility mediated by adducin polymorphism and/or dysregulation. Given the functional diversity of adducin in different cellular compartments, we aim to provide a knowledge base whereby its pathophysiological roles can be better understood. More importantly, we aim to provide novel insights that may be of significance in turning the adducin model to clinical application.

Identification of polymorphisms in 12q24.1, ACAD10, and BRAP as novel genetic determinants of blood pressure in Japanese by exome-wide association studies

We performed exome-wide association studies to identify genetic variants that influence systolic or diastolic blood pressure or confer susceptibility to hypertension in Japanese. The exome-wide association studies were performed with the use of Illumina HumanExome-12 DNA Analysis BeadChip or Infinium Exome-24 BeadChip arrays and with 14,678 subjects, including 8215 individuals with hypertension and 6463 controls. The relation of genotypes of 41,843 single nucleotide polymorphisms to systolic or diastolic blood pressure was examined by linear regression analysis. After Bonferroni's correction, 44 and eight polymorphisms were significantly (P < 1.19 × 10⁻⁶) associated with systolic or diastolic blood pressure, respectively, with six polymorphisms (rs12229654, rs671, rs11066015, rs2074356, rs3782886, rs11066280) being associated with both systolic and diastolic blood pressure. Examination of the relation of allele frequencies to hypertension with Fisher's exact test revealed that 100 of the 41,843 single nucleotide polymorphisms were significantly (P < 1.19 × 10⁻⁶) associated with hypertension. Subsequent multivariable logistic regression analysis with adjustment for age and sex showed that five polymorphisms (rs150854849, rs202069030, rs139012426, rs12229654, rs76974938) were significantly (P < 1.25 × 10⁻⁴) associated with hypertension. The polymorphism rs12229654 was thus associated with both systolic and diastolic blood pressure and with hypertension. Six polymorphisms (rs12229654 at 12q24.1, rs671 of ALDH2, rs11066015 of ACAD10, rs2074356 and rs11066280 of HECTD4, and rs3782886 of BRAP) were found to be associated with both systolic and diastolic blood pressure, with those at 12q24.1 or in ACAD10 or BRAP being novel determinants of blood pressure in Japanese.

Applicability of Precision Medicine Approaches to Managing Hypertension in Rural Populations

As part of the Heart Healthy Lenoir Project, we developed a practice level intervention to improve blood pressure control. The goal of this study was: (i) to determine if single nucleotide polymorphisms (SNPs) that associate with blood pressure variation, identified in large studies, are applicable to blood pressure control in subjects from a rural population; (ii) to measure the association of these SNPs with subjects' responsiveness to the hypertension intervention; and (iii) to identify other SNPs that may help understand patient-specific responses to an intervention. We used a combination of candidate SNPs and genome-wide analyses to test associations with either baseline systolic blood pressure (SBP) or change in systolic blood pressure one year after the intervention in two genetically defined ancestral groups: African Americans (AA) and Caucasian Americans (CAU). Of the 48 candidate SNPs, 13 SNPs associated with baseline SBP in our study; however, one candidate SNP, rs592582, also associated with a change in SBP after one year. Using our study data, we identified 4 and 15 additional loci that associated with a change in SBP in the AA and CAU groups, respectively. Our analysis of gene-age interactions identified genotypes associated with SBP improvement within different age groups of our populations. Moreover, our integrative analysis identified AQP4-AS1 and PADI2 as genes whose expression levels may contribute to the pleiotropy of complex traits involved in cardiovascular health and blood pressure regulation in response to an intervention targeting hypertension. In conclusion, the identification of SNPs associated with the success of a hypertension treatment intervention suggests that genetic factors in combination with age may contribute to an individual's success in lowering SBP. If these findings prove to be applicable to other populations, the use of this genetic variation in making patient-specific interventions may help providers with making decisions to improve patient outcomes. Further investigation is required to determine the role of this genetic variance with respect to the management of hypertension such that more precise treatment recommendations may be made in the future as part of personalized medicine.

A prospective study of the impact of AGTR1 A1166C on the effects of candesartan in patients with heart failure

AIM

To evaluate the impact of AGTR1 A1166C (rs5186) on the response to candesartan in patients with heart failure.

MATERIALS & METHODS

Prospective, multicentre, open-label study. We studied 299 symptomatic patients with heart failure presenting a left ventricular ejection fraction ≤40%.

RESULTS

Reductions in the primary end points of natriuretic peptides were not significantly associated with AGTR1 A1166C. Nevertheless, carrying the 1166C allele was associated with a greater compensatory increase in renin activity (p = 0.037) after 16 weeks of treatment with candesartan and a more modest effect on aldosterone concentrations (p = 0.022).

CONCLUSION

AGTR1 1166C carriers may experience a greater long-term compensatory renin-angiotensin-aldosterone system activation following treatment with candesartan. Whether these associations ultimately influence clinical outcomes requires investigation. Clinicaltrials.gov : NCT00400582.

The JAK2 GGCC (46/1) Haplotype in Myeloproliferative Neoplasms: Causal or Random?

The germline JAK2 haplotype known as “GGCC or 46/1 haplotype” (haplotype^GGCC_46/1) consists of a combination of single nucleotide polymorphisms (SNPs) mapping in a region of about 250 kb, extending from the JAK2 intron 10 to the Insulin-like 4 (INLS4) gene. Four main SNPs (rs3780367, rs10974944, rs12343867, and rs1159782) generating a “GGCC” combination are more frequently indicated to represent the JAK2 haplotype. These SNPs are inherited together and are frequently associated with the onset of myeloproliferative neoplasms (MPN) positive for both JAK2 V617 and exon 12 mutations. The association between the JAK2 haplotype^GGCC_46/1 and mutations in other genes, such as thrombopoietin receptor (MPL) and calreticulin (CALR), or the association with triple negative MPN, is still controversial. This review provides an overview of the frequency and the role of the JAK2 haplotype^GGCC_46/1 in the pathogenesis of different myeloid neoplasms and describes the hypothetical mechanisms at the basis of the association with JAK2 gene mutations. Moreover, possible clinical implications are discussed, as different papers reported contrasting data about the correlation between the JAK2 haplotype^GGCC_46/1 and blood cell count, survival, or disease progression.