Over 1000 genetic loci influencing blood pressure with multiple systems and tissues implicated.

High blood pressure (BP) remains the major heritable and modifiable risk factor for cardiovascular disease. Persistent high BP, or hypertension, is a complex trait with both genetic and environmental interactions. Despite swift advances in genomics, translating new discoveries to further our understanding of the underlying molecular mechanisms remains a challenge. More than 500 loci implicated in the regulation of BP have been revealed by genome-wide association studies (GWAS) in 2018 alone, taking the total number of BP genetic loci to over 1000. Even with the large number of loci now associated to BP, the genetic variance explained by all loci together remains low (~5.7%). These genetic associations have elucidated mechanisms and pathways regulating BP, highlighting potential new therapeutic and drug repurposing targets. A large proportion of the BP loci were discovered and reported simultaneously by multiple research groups, creating a knowledge gap, where the reported loci to date have not been investigated in a harmonious way. Here, we review the BP-associated genetic variants reported across GWAS studies and investigate their potential impact on the biological systems using in silico enrichment analyses for pathways, tissues, gene ontology and genetic pleiotropy.

Candidates registered for reasonable adjustments underperform compared to other candidates in the national undergraduate Prescribing Safety Assessment: Retrospective cohort analysis (2014-2018).

AIMS: Candidates with disabilities are eligible for reasonable adjustments (RA) while undertaking the national Prescribing Safety Assessment (PSA). The PSA is a novel open-book, time-constrained, multiformat assessment that may pose challenges to candidates with dyslexia and other disabilities. METHODS: Retrospective cohort analysis of 36 140 UK candidates undertaking first-sitting of the PSA (2014-2018). RESULTS: Of the 36 140 candidates, 9.1% (3284) were registered for RA. The RA group had lower pass rates (absolute difference 1.94%, 95% confidence interval 1.01-2.87%; P < .001) and assessment scores (1.16 percentage marks, 95% confidence interval 0.83-1.48; P < .001) compared with the non-RA group. This absolute difference is small relative to overall variability. This difference persists after adjusting for confounding factors (medical school and paper), and was present for all 8 different question types. The attainment gap within each medical school is negatively correlated with the school's overall performance, both in terms of pass rate (P < .001) and scores (P = .01). The RA group were also less likely to perceive the PSA as an appropriate test, having easy to follow layout/presentation or clear/unambiguous questions, even after adjusting for candidate performance. CONCLUSION: This analysis identifies slight differences in academic performance of candidates requiring RA in a national undergraduate assessment. The study is limited by the unavailability of data on ethnicity, sex, age, diagnosis and time of diagnosis. While further research is required to determine the cause of the attainment gap, this study emphasises the need to maintain a careful review on the fairness and validity of all aspects of the assessment.

The biological impact of blood pressure-associated genetic variants in the natriuretic peptide receptor C gene on human vascular smooth muscle.

Elevated blood pressure (BP) is a major global risk factor for cardiovascular disease. Genome-wide association studies have identified several genetic variants at the NPR3 locus associated with BP, but the functional impact of these variants remains to be determined. Here we confirmed, by a genome-wide association study within UK Biobank, the existence of two independent BP-related signals within NPR3 locus. Using human primary vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) from different individuals, we found that the BP-elevating alleles within one linkage disequilibrium block identified by the sentinel variant rs1173771 was associated with lower endogenous NPR3 mRNA and protein levels in VSMCs, together with reduced levels in open chromatin and nuclear protein binding. The BP-elevating alleles also increased VSMC proliferation, angiotensin II-induced calcium flux and cell contraction. However, an analogous genotype-dependent association was not observed in vascular ECs. Our study identifies novel, putative mechanisms for BP-associated variants at the NPR3 locus to elevate BP, further strengthening the case for targeting NPR-C as a therapeutic approach for hypertension and cardiovascular disease prevention.

Increased NBCn1 expression, Na+/HCO3- co-transport and intracellular pH in human vascular smooth muscle cells with a risk allele for hypertension.

Genome-wide association studies have revealed an association between variation at the SLC4A7 locus and blood pressure. SLC4A7 encodes the electroneutral Na+/HCO3- co-transporter NBCn1 which regulates intracellular pH (pHi). We conducted a functional study of variants at this locus in primary cultures of vascular smooth muscle and endothelial cells. In both cell types, we found genotype-dependent differences for rs13082711 in DNA-nuclear protein interactions, where the risk allele is associated with increased SLC4A7 expression level, NBCn1 availability and function as reflected in elevated steady-state pHi and accelerated recovery from intracellular acidosis. However, in the presence of Na+/H+ exchange activity, the SLC4A7 genotypic effect on net base uptake and steady-state pHi persisted only in vascular smooth muscle cells but not endothelial cells. We found no discernable effect of the missense polymorphism resulting in the amino acid substitution Glu326Lys. The finding of a genotypic influence on SLC4A7 expression and pHi regulation in vascular smooth muscle cells provides an insight into the molecular mechanism underlying the association of variation at the SLC4A7 locus with blood pressure.

Coronary-Heart-Disease-Associated Genetic Variant at the COL4A1/COL4A2 Locus Affects COL4A1/COL4A2 Expression, Vascular Cell Survival, Atherosclerotic Plaque Stability and Risk of Myocardial Infarction.

Genome-wide association studies have revealed an association between coronary heart disease (CHD) and genetic variation on chromosome 13q34, with the lead single nucleotide polymorphism rs4773144 residing in the COL4A2 gene in this genomic region. We investigated the functional effects of this genetic variant. Analyses of primary cultures of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) from different individuals showed a difference between rs4773144 genotypes in COL4A2 and COL4A1 expression levels, being lowest in the G/G genotype, intermediate in A/G and highest in A/A. Chromatin immunoprecipitation followed by allelic imbalance assays of primary cultures of SMCs and ECs that were of the A/G genotype revealed that the G allele had lower transcriptional activity than the A allele. Electrophoretic mobility shift assays and luciferase reporter gene assays showed that a short DNA sequence encompassing the rs4773144 site interacted with a nuclear protein, with lower efficiency for the G allele, and that the G allele sequence had lower activity in driving reporter gene expression. Analyses of cultured SMCs from different individuals demonstrated that cells of the G/G genotype had higher apoptosis rates. Immunohistochemical and histological examinations of ex vivo atherosclerotic coronary arteries from different individuals disclosed that atherosclerotic plaques with the G/G genotype had lower collagen IV abundance and thinner fibrous cap, a hallmark of unstable, rupture-prone plaques. A study of a cohort of patients with angiographically documented coronary artery disease showed that patients of the G/G genotype had higher rates of myocardial infarction, a phenotype often caused by plaque rupture. These results indicate that the CHD-related genetic variant at the COL4A2 locus affects COL4A2/COL4A1 expression, SMC survival, and atherosclerotic plaque stability, providing a mechanistic explanation for the association between the genetic variant and CHD risk.

A blood pressure-associated variant of the SLC39A8 gene influences cellular cadmium accumulation and toxicity.

Genome-wide association studies have revealed a relationship between inter-individual variation in blood pressure and the single nucleotide polymorphism rs13107325 in the SLC39A8 gene. This gene encodes the ZIP8 protein which co-transports divalent metal cations, including heavy metal cadmium, the accumulation of which has been associated with increased blood pressure. The polymorphism results in two variants of ZIP8 with either an alanine (Ala) or a threonine (Thr) at residue 391. We investigated the functional impact of this variant on protein conformation, cadmium transport, activation of signalling pathways and cell viability in relation to blood pressure regulation. Following incubation with cadmium, higher intracellular cadmium was detected in cultured human embryonic kidney cells (HEK293) expressing heterologous ZIP8-Ala391, compared with HEK293 cells expressing heterologous ZIP8-Thr391. This Ala391-associated cadmium accumulation also increased the phosphorylation of the signal transduction molecule ERK2, activation of the transcription factor NFκB, and reduced cell viability. Similarly, vascular endothelial cells with the Ala/Ala genotype had higher intracellular cadmium concentration and lower cell viability than their Ala/Thr counterpart following cadmium exposure. These results indicate that the ZIP8 Ala391-to-Thr391 substitution has an effect on intracellular cadmium accumulation and cell toxicity, providing a potential mechanistic explanation for the association of this genetic variant with blood pressure.

UK survey of non-medical use of prescription drugs (NMURx) as a valuable source of general population illicit drug use data.

PURPOSE OF STUDY: The aim of the study is to describe the prevalence of illicit drug use in England and Wales using data from the UK Survey of Non-Medical Use of Prescription Drugs (NMURx) programme and to compare against the well-established Crime Survey England and Wales (CSEW). The rationale is that recreational and illicit drug use is common, but the prevalence is difficult to estimate with personal interviewing methods. STUDY DESIGN: We compared two cross-sectional population surveys (NMURx, n=8903 and CSEW, n=20 685) with data regarding self-reported recreational drug use and demographics. NMURx is an online survey using non-probability sampling methodology with preset demographical quotas based on census data. CSEW surveys drug use via computer-assisted self-interviewing as part of a computer-assisted personal-interviewing crime survey. RESULTS: Cannabis was the most frequently used drug regardless of demographics. Prevalence of drug use for specific substances was generally higher for males, younger ages and students. The relationship between income and drug misuse is less clear. Self-reported prevalence of drug use in the NMURx survey is consistently higher than CSEW (absolute difference 1%-3 % across substances and timescales) and persists after stratification for gender, age, student status and household income. CONCLUSIONS: The NMURx survey has a broad reach of participants, and a sampling scheme that achieves external validity, compared with general population demographics. NMURx's online format allows flexibility in items surveyed and in response to emerging trends. The self-reported drug use in the NMURx cohort is comparable, although slightly higher, than the CSEW estimates.

ADAMTS7 cleavage and vascular smooth muscle cell migration is affected by a coronary-artery-disease-associated variant.

Recent genome-wide association studies have revealed an association between variation at the ADAMTS7 locus and susceptibility to coronary artery disease (CAD). Furthermore, in a population-based study cohort, we observed an inverse association between atherosclerosis prevalence and rs3825807, a nonsynonymous SNP (A to G) leading to a Ser-to-Pro substitution in the prodomain of the protease ADAMTS7. In light of these data, we sought a mechanistic explanation for this association. We found that ADAMTS7 accumulated in smooth muscle cells in coronary and carotid atherosclerotic plaques. Vascular smooth muscle cells (VSMCs) of the G/G genotype for rs3825807 had reduced migratory ability, and conditioned media of VSMCs of the G/G genotype contained less of the cleaved form of thrombospondin-5, an ADAMTS7 substrate that had been shown to be produced by VSMCs and inhibit VSMC migration. Furthermore, we found that there was a reduction in the amount of cleaved ADAMTS7 prodomain in media conditioned by VSMCs of the G/G genotype and that the Ser-to-Pro substitution affected ADAMTS7 prodomain cleavage. The results of our study indicate that rs3825807 has an effect on ADAMTS7 maturation, thrombospondin-5 cleavage, and VSMC migration, with the variant associated with protection from atherosclerosis and CAD rendering a reduction in ADAMTS7 function.

Functional analyses of coronary artery disease associated variation on chromosome 9p21 in vascular smooth muscle cells.

Variation on chromosome 9p21 is associated with risk of coronary artery disease (CAD). This genomic region contains the CDKN2A and CDKN2B genes which encode the cell cycle regulators p16(INK4a), p14(ARF) and p15(INK4b) and the ANRIL gene which encodes a non-coding RNA. Vascular smooth muscle cell (VSMC) proliferation plays an important role in the pathogenesis of atherosclerosis which causes CAD. We ascertained whether 9p21 genotype had an influence on CDKN2A/CDKN2B/ANRIL expression levels in VSMCs, VSMC proliferation and VSMC content in atherosclerotic plaques. Immunohistochemical examination showed that VSMCs in atherosclerotic lesions expressed p16(INK4a), p14(ARF) and p15(INK4b). Analyses of primary cultures of VSMCs showed that the 9p21 risk genotype was associated with reduced expression of p16(INK4a), p15(INK4b) and ANRIL (P = 1.2 × 10(-5), 1.4 × 10(-2) and 3.1 × 10(-9)) and with increased VSMC proliferation (P = 1.6 × 10(-2)). Immunohistochemical analyses of atherosclerotic plaques revealed an association of the risk genotype with reduced p15(INK4b) levels in VSMCs (P = 3.7 × 10(-2)) and higher VSMC content (P = 5.6 × 10(-4)) in plaques. The results of this study indicate that the 9p21 variation has an impact on CDKN2A and CDKN2B expression in VSMCs and influences VMSC proliferation, which likely represents an important mechanism for the association between this genetic locus and susceptibility to CAD.

A retrospective cohort study of risk factors and outcomes in older patients admitted to an inner-city geriatric unit in London during first peak of COVID-19 pandemic.

PURPOSE: Compared to younger patients, coronavirus disease 2019 (COVID-19) clinical presentation in older people can be more heterogeneous and fatal. We aim to describe a cohort of older adults admitted in an inner-city London hospital during the first peak of the pandemic. METHODS: A retrospective observational study that enrolled older adults consecutively admitted into two geriatric wards with suspected or confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We collected socio-demographic data, comorbidities, symptoms at presentation and/or during admission, biochemical and radiological data and outcomes at 28 days. RESULTS: One hundred twenty-four patients were included, and 75% were > 80 years old. 19.5% of COVID-19 cases were judged to be hospital-acquired. More than half presented or developed typical symptoms, respiratory failure or fatigue. 46.8% were diagnosed with delirium, 24.2% with falls and dysphagia was present in 13.7%. The mortality rate was 29.8% and was higher among males, those > 80 years, patients with a higher grade of frailty, a history of dementia or chronic kidney disease, as well as those diagnosed with respiratory failure, acute kidney injury or hypernatremia. Independent predictors of mortality were male sex, age > 80 years, respiratory failure and hypernatremia. CONCLUSION: We have described a cohort of patients with SARS-CoV-2 infection in the first UK peak of the global pandemic. We found that these patients had significant frailty with multiple comorbidities. There was a high mortality and increased dependency and greater social care need in survivors.

Black renal transplant recipients have poorer long-term graft survival than CYP3A5 expressers from other ethnic groups.

BACKGROUND: African American transplant recipients have poorer long-term outcomes than Caucasian Americans. This difference was not found in French patients, suggesting socialized medicine overcame this disparity. It has also been hypothesized that the difference relates to the higher prevalence of Black individuals who express the metabolic enzyme cytochrome P4503A5 (CYP3A5), with consequent altered handling of immunosuppressive drugs. METHODS: Records of 555 (50 Black; 505 non-Black) sequential renal transplant recipients from a single UK centre were analysed. RESULTS: Outcomes were significantly worse for Black patients: death-censored graft survival (5-year 66% versus 87%, P = 0.001); halving of year one estimated glomerular filtration rate (mean 8.8 versus 10.8 years, P = 0.008); first-year graft loss (12% versus 3.8%, P = 0.02); and death-censored graft survival in patients surviving the first year with functioning grafts (5-year 77% versus 94%, P = 0.02). Death-censored 5-year graft survival was poorer in Black CYP3A5 expressers than in non-Black CYP3A5 expressers (62% versus 93%, P = 0.002). Following multivariate analysis, the Black group demonstrated poorer graft survival as compared to the non-Black group (hazard ratio 0.46, 95% CI 0.25-0.85, P = 0.002). In a subgroup of genotyped transplant recipients, ethnicity (hazard ratio 0.31, 95% CI 0.15-0.64, P = 0.002), and not CYP3A5 expresser status, persists as an independent risk factor for graft survival following multivariate analysis. CONCLUSION: In this cohort of patients with socialized medicine, Black recipients had poorer long-term outcomes than individuals from other ethnic groups. This was independent of CYP3A5 expresser status.

Hypertension genomics and cardiovascular prevention.

Hypertension continues to be a major risk factor for global mortality, and recent genome-wide association studies (GWAS) have expanded in size, leading to the identification of further genetic loci influencing blood pressure. In light of the new knowledge from the largest cardiovascular GWAS to date, we review the potential impact of genomics on discovering potential drug targets, risk stratification with genetic risk scores, drug selection with pharmacogenetics, and exploring insights provided by gene-environment interactions.

Attenuation of Splanchnic Autotransfusion Following Noninvasive Ultrasound Renal Denervation: A Novel Marker of Procedural Success.

BACKGROUND: Renal denervation has no validated marker of procedural success. We hypothesized that successful renal denervation would reduce renal sympathetic nerve signaling demonstrated by attenuation of α-1-adrenoceptor-mediated autotransfusion during the Valsalva maneuver. METHODS AND RESULTS: In this substudy of the Wave IV Study: Phase II Randomized Sham Controlled Study of Renal Denervation for Subjects With Uncontrolled Hypertension, we enrolled 23 subjects with resistant hypertension. They were randomized either to bilateral renal denervation using therapeutic levels of ultrasound energy (n=12) or sham application of diagnostic ultrasound (n=11). Within-group changes in autonomic parameters, office and ambulatory blood pressure were compared between baseline and 6 months in a double-blind manner. There was significant office blood pressure reduction in both treatment (16.1±27.3 mm Hg, P<0.05) and sham groups (27.9±15.0 mm Hg, P<0.01) because of which the study was discontinued prematurely. However, during the late phase II (Iii) of Valsalva maneuver, renal denervation resulted in substantial and significant reduction in mean arterial pressure (21.8±25.2 mm Hg, P<0.05) with no significant changes in the sham group. Moreover, there were significant reductions in heart rate in the actively treated group at rest (6.0±11.5 beats per minute, P<0.05) and during postural changes (supine 7.2±8.4 beats per minute, P<0.05, sit up 12.7±16.7 beats per minute, P<0.05), which were not observed in the sham group. CONCLUSIONS: Blood pressure reduction per se is not necessarily a marker of successful renal nerve ablation. Reduction in splanchnic autotransfusion following renal denervation has not been previously demonstrated and denotes attenuation of (renal) sympathetic efferent activity and could serve as a marker of procedural success. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02029885.

Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits.

High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic and pulse pressure) to date in over 1 million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also highlight shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future.

Publisher Correction: Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits.

In the version of this article originally published, the name of author Martin H. de Borst was coded incorrectly in the XML. The error has now been corrected in the HTML version of the paper.

Exploring hypertension genome-wide association studies findings and impact on pathophysiology, pathways, and pharmacogenetics.

UNLABELLED: Hypertension is a major risk factor for global mortality. Recent genome-wide association studies (GWAS) have led to successful identification of many genetic loci influencing blood pressure, although these studies account for less than 5% of heritability. While genetic discovery efforts continue, it is timely to pause and reflect on what information has been gained to date from reported loci. Knowledge from GWAS findings inform our understanding of the pathways and pleiotropy underpinning hypertension and aid in the identification of potential druggable targets. By reviewing blood pressure loci we aim to determine how much potential the current observations have for future clinical utility. CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article.

Expression and function of the K+ channel KCNQ genes in human arteries.

BACKGROUND AND PURPOSE: KCNQ-encoded voltage-gated potassium channels (K(v) 7) have recently been identified as important anti-constrictor elements in rodent blood vessels but the role of these channels and the effects of their modulation in human arteries remain unknown. Here, we have assessed KCNQ gene expression and function in human arteries ex vivo. EXPERIMENTAL APPROACH: Fifty arteries (41 from visceral adipose tissue, 9 mesenteric arteries) were obtained from subjects undergoing elective surgery. Quantitative RT-PCR experiments using primers specific for all known KCNQ genes and immunohistochemsitry were used to show K(v) 7 channel expression. Wire myography and single cell electrophysiology assessed the function of these channels. KEY RESULTS: KCNQ4 was expressed in all arteries assessed, with variable contributions from KCNQ1, 3 and 5. KCNQ2 was not detected. K(v) 7 channel isoform-dependent staining was revealed in the smooth muscle layer. In functional studies, the K(v) 7 channel blockers, XE991 and linopirdine increased isometric tension and inhibited K(+) currents. In contrast, the K(v) 7.1-specific blocker chromanol 293B did not affect vascular tone. Two K(v) 7 channel activators, retigabine and acrylamide S-1, relaxed preconstricted arteries, actions reversed by XE991. K(v) 7 channel activators also suppressed spontaneous contractile activity in seven arteries, reversible by XE991. CONCLUSIONS AND IMPLICATIONS: This is the first study to demonstrate not only the presence of KCNQ gene products in human arteries but also their contribution to vascular tone ex vivo. LINKED ARTICLE: This article is commented on by Mani and Byron, pp. 38-41 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2010.01065.x.

Pharmacogenetics as a tool for optimising drug therapy in solid-organ transplantation.

Existing immunosuppressive therapies used for solid-organ transplantation have narrow therapeutic indices, whereby underdosing is associated with acute immunological rejection of the transplanted organ and overdosing is associated with infections and malignancy, as well as organ-specific toxicities. There is significant inter-individual variation in the pharmacokinetics and pharmacodynamics of these drugs, an issue that has been addressed, in part, by therapeutic drug monitoring. Genetic polymorphisms in drug metabolising enzymes, drug efflux pumps and drug targets which may underly this heterogeneity have been identified and may provide a tool to guide prescribing. There are a number of associations between genotype and pharmacology, but as of now, only thiopurine-S-methyltransferase and cytochrome P450 3A5 have a sufficiently large influence to have potential in guiding therapy. Recent studies have also identified that donor genotype may play a significant role in immunosuppressive drug pharmacokinetics and pharmacodynamics.