Haplotypes of the WNK1 gene associate with blood pressure variation in a severely hypertensive population from the British Genetics of Hypertension study

Navigating the multifaceted intricacies of the Na+-Cl- cotransporter, a highly regulated key effector in the control of hydromineral homeostasis

The Na+-Cl- cotransporter (NCC; SLC12A3) is a highly regulated integral membrane protein that is known to exist as three splice variants in primates. Its primary role in the kidney is to mediate the cosymport of Na+ and Cl- across the apical membrane of the distal convoluted tubule. Through this role and the involvement of other ion transport systems, NCC allows the systemic circulation to reclaim a fraction of the ultrafiltered Na+, K+, Cl-, and Mg+ loads in exchange for Ca2+ and [Formula: see text]. The physiological relevance of the Na+-Cl- cotransport mechanism in humans is illustrated by several abnormalities that result from NCC inactivation through the administration of thiazides or in the setting of hereditary disorders. The purpose of the present review is to discuss the molecular mechanisms and overall roles of Na+-Cl- cotransport as the main topics of interest. On reading the narrative proposed, one will realize that the knowledge gained in regard to these themes will continue to progress unrelentingly no matter how refined it has now become.

Comprehensive analysis of lncRNA-miRNA-mRNA ceRNA network in ischemic stroke

Objective

Competitive endogenous RNA (ceRNA) networks have uncovered a novel mode of RNA interaction, and are implicated in various biological processes and the pathogenesis of IS. This study aimed to explore the potential mechanisms underlying the ceRNA network in IS.

Methods

Four public datasets containing lncRNA and mRNA (GSE22255 and GSE16561) and miRNA (GSE55937 and GSE43618) expression profiles from the GEO database were systematically analyzed to explore the role of RNAs in ischemic stroke (IS). Differentially expressed mRNAs (DEmRNAs), lncRNAs (DElncRNAs), and miRNAs (DEmiRNAs) between IS and normal control samples were identified. LncRNA-miRNA and miRNA-mRNA interactions were predicted, and the competing endogenous RNA (ceRNA) regulatory network was constructed using the Cytoscape software. The correlation between the RNAs in the ceRNA network and the clinical features of the samples was evaluated. Finally, principal component analysis was performed on the RNAs that constitute the ceRNA regulatory network, and their differential expression and principal component relationships among different types of samples were observed.

Results

A total of 224 DEmRNAs, 7 DEmiRNAs, and four DElncRNAs related to IS in four datasets were identified. Then, through target gene prediction, a lncRNA-miRNA-mRNA ceRNA network that contained 3 DElncRNAs, 2 DEmiRNAs, and 24 DEmRNAs was constructed. Correlations of the clinical characteristics showed that PART1 and SERPINH1 were related to clinical diseases, WNK1 was related to lifestyle, and seven RNAs were related to age. PCA results indicate that three principal components of PC1, PC2, and PC3 can clearly distinguish between control and IS samples.

Conclusion

Overall, we constructed a ceRNA network in IS, which could offer insights into the molecular mechanism and potential prognostic biomarkers for further research.

Transforming Medical Paradigms: A Cutting-Edge Review of Genomic and Robotic Medical and Surgical Approaches in the Battle Against Diabetes, Hypertension, and Cardiovascular Issues

This article provides an in-depth review of the current state of management for diabetes, hypertension, and cardiovascular disease, focusing on advancements from genomics to robotics. It explores the role of genomic markers in personalized medicine, offering tailored treatment options for these chronic conditions. The article also examines the efficacy of various pharmacological and surgical interventions, including bariatric surgery for diabetes and device-based treatments for hypertension. A comparative analysis is presented to evaluate the cost-effectiveness and patient outcomes between medical and surgical approaches. The review concludes that while personalized medicine and minimally invasive surgical techniques show promise, more high-quality comparative research is needed. The ultimate goal is to integrate these emerging technologies within a framework of evidence-based medicine to improve patient outcomes and health equity.

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

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

A Possible Link between Gut Microbiome Composition and Cardiovascular Comorbidities in Psoriatic Patients

Cardiovascular disease (CVD) is one of the most common comorbidities that may affect psoriatic patients. Several exogenous and endogenous factors are involved in the etiology and progression of both psoriasis and CVD. A potential genetic link between the two diseases has emerged; however, some gaps remain in the understanding of the CVD prevalence in psoriatic patients. Recently, the role of the gut microbiome dysbiosis was documented in the development and maintenance of both diseases. To investigate whether gut microbiome dysbiosis might influence the occurrence of CVD in psoriatic patients, 16S rRNA gene sequencing was performed to characterize the gut microbiome of 28 psoriatic patients, including 17 patients with and 11 without CVD. The comparison of the gut microbiome composition between patients with and without CVD showed a higher prevalence of Barnesiellaceae and Phascolarctobacterium in patients with CVD. Among patients with CVD, those undergoing biologic therapy had lower abundance levels of Barnesiellaceae, comparable to those found in patients without CVD. Overall, these findings suggest that the co-occurrence of psoriasis and CVD might be linked to gut microbiome dysbiosis and that therapeutic strategies could help to restore the intestinal symbiosis, potentially improving the clinical management of psoriasis and its associated comorbidities.

Analysis of the Potential Genetic Links between Psoriasis and Cardiovascular Risk Factors

Cardiovascular risk factors are one of the most common comorbidities in psoriasis. A higher prevalence of hypertension, insulin resistance and type 2 diabetes, dyslipidemia, obesity, metabolic syndrome, depression, as well as cardiovascular disease was confirmed in psoriatic patients in comparison to the general population. Data suggest that psoriasis and systemic inflammatory disorders may originate from the pleiotropic interactions with many genetic pathways. In this review, the authors present the current state of knowledge on the potential genetic links between psoriasis and cardiovascular risk factors. The understanding of the processes linking psoriasis with cardiovascular risk factors can lead to improvement of psoriasis management in the future.

Regulatory control of the Na-Cl co-transporter NCC and its therapeutic potential for hypertension

Hypertension is the largest risk factor for cardiovascular disease, the leading cause of mortality worldwide. As blood pressure regulation is influenced by multiple physiological systems, hypertension cannot be attributed to a single identifiable etiology. Three decades of research into Mendelian forms of hypertension implicated alterations in the renal tubular sodium handling, particularly the distal convoluted tubule (DCT)-native, thiazide-sensitive Na-Cl cotransporter (NCC). Altered functions of the NCC have shown to have profound effects on blood pressure regulation as illustrated by the over activation and inactivation of the NCC in Gordon's and Gitelman syndromes respectively. Substantial progress has uncovered multiple factors that affect the expression and activity of the NCC. In particular, NCC activity is controlled by phosphorylation/dephosphorylation, and NCC expression is facilitated by glycosylation and negatively regulated by ubiquitination. Studies have even found parvalbumin to be an unexpected regulator of the NCC. In recent years, there have been considerable advances in our understanding of NCC control mechanisms, particularly via the pathway containing the with-no-lysine [K] (WNK) and its downstream target kinases, SPS/Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress responsive 1 (OSR1), which has led to the discovery of novel inhibitory molecules. This review summarizes the currently reported regulatory mechanisms of the NCC and discusses their potential as therapeutic targets for treating hypertension.

Pharmacogenomics of amlodipine and hydrochlorothiazide therapy and the quest for improved control of hypertension: a mini review

Blood pressure (BP) is a complex trait that is regulated by multiple physiological pathways and include but is not limited to extracellular fluid volume homeostasis, cardiac contractility, and vascular tone through renal, neural, or endocrine systems. Uncontrolled hypertension (HTN) has been associated with an increased mortality risk. Therefore, understanding the genetics that underpins and influence BP regulation will have a major impact on public health. Moreover, uncontrolled HTN has been linked to inter-individual variation in the drugs’ response and this has been associated with an individual’s genetics architecture. However, the identification of candidate genes that underpin the genetic basis of HTN remains a major challenge. To date, few variants associated with inter-individual BP regulation have been identified and replicated. Research in this field has accelerated over the past 5 years as a direct result of on-going genome-wide association studies (GWAS) and the progress in the identification of rare gene variants and mutations, epigenetic markers, and the regulatory pathways involved in the pathophysiology of BP. In this review we describe and enhance our current understanding of how genetic variants account for the observed variability in BP response in patients on first-line antihypertensive drugs, amlodipine and hydrochlorothiazide.

Whole Blood Gene Expression Associated With Clinical Biological Age

Background

Biologic age may better reflect an individual's rate of aging than chronologic age.

Methods

We conducted a transcriptome-wide association study with biologic age estimated with clinical biomarkers, which included: systolic blood pressure, forced expiratory volume at 1 second (FEV1), total cholesterol, fasting glucose, C-reactive protein, and serum creatinine. We assessed the association between the difference between biologic age and chronologic age (∆age) and gene expression in whole blood measured using the Affymetrix Human Exon 1.0st Array.

Results

Our discovery sample included 2,163 participants from the Framingham Offspring cohort (mean age 67 ± 9 years, 55% women). A total of 481 genes were significantly associated with ∆age (p < 2.8 × 10-6). Among them, 415 genes were validated (p < .05/481 = 1.0 × 10-4) in 2,946 participants from the Framingham Third Generation cohort (mean age 46 ± 9 years, 53% women). Many of the significant genes were involved in the ubiquitin-mediated proteolysis pathway. The replication in 414 Rotterdam Study participants (mean age 59 ± 8, 52% women) found 104 of 415 validated genes reached nominal significance (p < .05).

Conclusion

We identified and validated 415 genes associated with ∆age in a community-based cohort. Future functional characterization of the biologic age-related gene network may identify targets to test for interventions to delay aging in older adults.

A Molecular Docking Approach to Evaluate the Pharmacological Properties of Natural and Synthetic Treatment Candidates for Use against Hypertension

Cardiovascular diseases (CVDs) have become the leading cause of disability and death worldwide, particularly in low- and middle-income countries. Hypertension, a major cause of CVD progression, is widely attributable to genetic, behavioral, and environmental risk factors. Among the genetic reasons, angiotensin II enzyme, produced as a result of abnormal functioning of the renin⁻angiotensin system, is reported as the foremost cause of hypertension. A cascade of genes, including those encoding for WNK kinases (WNK1 and WNK4), Bp1, Bp2, angiotensinogen, and other enzymes, is involved in the conversion of angiotensin I to angiotensin II. However, the angiotensin-converting enzyme (ACE) plays a crucial role in this pathway. Therefore, ACE could be a potential therapeutic target in regulating the conversion of angiotensin I to angiotensin II and eventually controlling hypertension. In this study, a molecular docking-based approach was utilized for identifying and evaluating potential inhibitors of ACE present in herbs, other natural sources, and synthetic sources, on the basis of these compounds' binding affinities and other physicochemical features. In addition, the suitability of these inhibitors as drugs for biological systems, considering their adsorption, distribution, metabolism, and excretion (ADME), was predicted using Lipinski's rule. In conclusion, our study provides a novel and clearer insight into the interaction properties of known putative inhibitors of ACE.

Genetic association study between T-786C NOS3 polymorphism and essential hypertension in an Algerian population of the Oran city

BACKGROUND

Essential hypertension is an important risk factor for the development of cardiovascular disease. Important candidate genes such as NOS3 gene have been widely studied and reported to be associated with essential hypertension (HTN) in human populations.

AIM

We aim in this study to analyze the relationship between NOS3 -786T/C, a common genetic variant and HTN in a sample of the Algerian population of the Oran city.

METHODS

A case-control study has been performed in 154 subjects including 77 hypertensives and 77 normotensives. The recruitment of these subjects was done in local Health Centers of the city of Oran, West Algeria. HTN was defined as elevated systolic blood pressure SBD≥140  mmHg and or sustained diastolic blood pressure DBP≥90  mmHg, measured using an Omron^® Automatic BP Monitor - M-3W machine. Consents were obtained from all participants. Polymerase chain reaction (PCR) combined with restrictive fragment length polymorphism (RFLP) was used to genotype the NOS -786T/C variant.

RESULTS

The distribution of the allelic frequencies did not differ between cases and controls (OR = 1.48; 95%CI [0.94-2.32], P = 0.09). However, after adjustment with the age, sex, and body mass index, we observed significant association between NOS -786C allele and HTN status (OR = 2.08; 95%CI [1.18-3.66], P = 0.01).

CONCLUSION

Our results indicate that the C allele of the NOS3 gene is associated with increased risk of essential hypertension in this sample of the Algerian population of the Oran city. Further validation in larger samples is needed to confirm this finding.

Novel SNPs of WNK1 and AKR1C3 are associated with preeclampsia

Preeclampsia is a hypertensive disorder of pregnancy and is one of the most common causes of poor perinatal outcomes. Preeclampsia increases the risk of hypertension in the future. Variants of WNK1 (lysine deficient protein kinase 1), ADRB2 (β2 adrenergic receptor), NEDD4L (ubiquitin-protein ligase NEDD4-like), KLK1 (kallikrein 1) contribute to hypertension, and AKR1C3 (aldo-keto reductase family1 member C3), is associated with preeclampsia. The association of single nucleotide polymorphisms (SNPs) in these five candidate preeclampsia susceptibility genes and the related traits in Chinese individuals were investigated. In this study, 13 SNPs of the five genes were genotyped in 276 preeclampsia patients and 229 age- and area-matched normal pregnancies in women of Chinese Northern Han origin. The 95% confidence interval (CI) and odds ratio (OR) were estimated by binary logistic regression. No obvious linkage disequilibrium or haplotypes were observed among these SNPs. Those with GG genotype and allele G of AKR1C3 (rs10508293) had a decreased risk of preeclampsia (adjusted OR = 3.011, 95% CI = 1.758-5.159, and adjusted OR = 1.745, 95% CI = 1.349-2.257, respectively). The AA genotype and allele A of WNK1 (rs1468326) were significantly associated with an increased risk in preeclampsia (adjusted OR = 2.307, 95% CI = 1.206-3.443, and adjusted OR = 1.663, 95% CI = 1.283-2.157, respectively). The findings indicate that the GG genotype of AKR1C3 rs10508293 is associated with decreased risk for preeclampsia and the AA genotype of WNK1 rs1468326 are related with an increased risk for preeclampsia.

Association of with-no-lysine kinase 1 and Serine/Threonine kinase 39 gene polymorphisms and haplotypes with essential hypertension in Tibetans

Tibetans have a higher essential hypertension prevalence compared with other ethnics in China. The reason might be due to their unique environmental influence, as well as genetic factor. However, limited studies focus on Tibetan genetics and its association with hypertension. The aim of this study was to investigate the association between With-No-Lysine (K) Kinase 1 (WNK1), Serine/Threonine kinase 39(STK39) genes variants and hypertension in the Tibetan population. 204 Tibetan hypertensive patients and 305 normotensive controls were recruited in an epidemiological survey conducted at 2 sites in the Ganzi Tibetan autonomous region. Patients were genotyped for nineteen WNK1 candidate tag single nucleotide polymorphisms (SNPs) and three STK39 SNPs, and haplotype analysis was performed. Results showed that the allele A in rs1468326 was overrepresented in hypertensive patients versus control (53.4% vs 42.9%, P < 0.05). The multivariable-adjusted odds ratio (OR) for hypertension among CA + AA genotypes carriers was 1.60 (95% CI: 1.02-2.62, P < 0.05), and they also had a higher systolic blood pressure (136.5 ± 28.6 vs 131.7 ± 24.8 mmHg, P < 0.05). However, the TT genotype ratio in rs6749447 was lower in hypertensives (5.4% vs 10.8%, P < 0.05), and the hypertension risk for the TT genotype carriers in rs6749447 decreased after adjustment (OR 0.49, 95% CI 0.19-0.95, P < 0.05). Subjects with haplotype AGACAGGAATCGT showed 1.57 times higher risk of hypertension (95% CI 1.02-2.41, P < 0.05). In conclusion, SNP rs1468326 of WNK1, rs6749447 of STK39, and WNK1 haplotype AGACAGGAATCGT were associated with hypertension in Tibetan individuals. Environ. Mol. Mutagen. 59:151-160, 2018. © 2017 Wiley Periodicals, Inc.

Mechanisms and controversies in mutant Cul3-mediated familial hyperkalemic hypertension

Autosomal dominant mutations in cullin-3 ( Cul3) cause the most severe form of familial hyperkalemic hypertension (FHHt). Cul3 mutations cause skipping of exon 9, which results in an internal deletion of 57 amino acids from the CUL3 protein (CUL3-∆9). The precise mechanism by which this altered form of CUL3 causes FHHt is controversial. CUL3 is a member of the cullin-RING ubiquitin ligase family that mediates ubiquitination and thus degradation of cellular proteins, including with-no-lysine [K] kinases (WNKs). In CUL3-∆9-mediated FHHt, proteasomal degradation of WNKs is abrogated, leading to overactivation of the WNK targets sterile 20/SPS-1 related proline/alanine-rich kinase and oxidative stress-response kinase-1, which directly phosphorylate and activate the thiazide-sensitive Na⁺-Cl^- cotransporter. Several groups have suggested different mechanisms by which CUL3-∆9 causes FHHt. The majority of these are derived from in vitro data, but recently the Kurz group (Schumacher FR, Siew K, Zhang J, Johnson C, Wood N, Cleary SE, Al Maskari RS, Ferryman JT, Hardege I, Figg NL, Enchev R, Knebel A, O'Shaughnessy KM, Kurz T. EMBO Mol Med 7: 1285-1306, 2015) described the first mouse model of CUL3-∆9-mediated FHHt. Analysis of this model suggested that CUL3-∆9 is degraded in vivo, and thus Cul3 mutations cause FHHt by inducing haploinsufficiency. We recently directly tested this model but found that other dominant effects of CUL3-∆9 must contribute to the development of FHHt. In this review, we focus on our current knowledge of CUL3-∆9 action gained from in vitro and in vivo models that may help unravel this complex problem.

Intra-arterial transplantation of human bone marrow mesenchymal stem cells (hBMMSCs) improves behavioral deficits and alters gene expression in rodent stroke model

Stroke is a multi-factorial polygenic disease and is a major cause of death and adult disability. Administration of bone marrow stem cells protects ischemic rat brain by facilitating recovery of neurological functions. But the molecular mechanism of stem cells action and their effect on gene expression is not well explored. In this study, we have transplanted 1 × 10⁶ human bone marrow mesenchymal stem cells (hBMMSCs) in middle cerebral artery occluded (MCAo) adult male Wistar rats through intracarotid artery route at 24 h after surgery. Motor behavioral tests (rotarod and open field) were performed to assess the changes in motor functions at day 0 and day1, 4, 8 and 14. The expression of studied genes at mRNA and protein level was quantified by using Q-PCR and western blotting, respectively. Further, we have assessed the methylation pattern of promoter of these genes by using methylation-specific PCR. Data were analyzed statistically and correlated. A significant improvement in behavioral deficits was observed in stem cells treated group after 14th day post stroke. Significantly (p < 0.05) increased mRNA and protein levels of brain derived neurotrophic factor and ANP genes in hBMMSCs treated group along with decrease in methylation level at their promoter was observed. On the other hand, significantly decreased mRNA and protein level of TSP1 and WNK1 in hBMMSCs treated group was observed. In conclusion, hBMMSCs administration significantly improves the behavioral deficits by improving motor and locomotor coordination. The promoter of TSP1 and WNK1 genes was found to be hyper-methylated in hBMMSCs group resulting in their decreased expression while the promoter of ANP and brain derived neurotrophic factor was found to be hypo-methylated. This study might shed a light on how hBMMSCs affect the gene expression by modulating methylation status.

Associations between PPARG polymorphisms and the risk of essential hypertension

Background

Peroxisome proliferator-activated receptor gamma (PPARG) plays an important role in the pathogenesis and maintenance of essential hypertension (EH). It has been suggested that polymorphisms of PPARG are associated with the risk of EH. However, findings to date remain controversial. To elucidate the associations between the PPARG Pro12Ala and C161T polymorphisms and EH risk, a meta-analysis was carried out.

Methods

A comprehensive literature search of PubMed, Embase, CNKI (Chinese National Knowledge Infrastructure), VIP and Wanfang databases was conducted. The pooled odds ratios (ORs) and 95% confidence interval (CI) were calculated to estimate the size of the effect using the random-effects model. At the same time, the pooled standardized mean difference (SMD) with 95% CI was used for the meta-analysis of the PPARG Pro12Ala polymorphism and blood pressure.

Results

Finally, Fifteen papers (seventeen studies) including 4,151 cases and 4,997 controls to evaluate the association of the PPARGPro12Ala polymorphism and EH risk, were included in this study. Overall, the results suggested that Ala allele was associated with the decreased EH risk (for allelic model, OR = 0.757, 95%CI: 0.624–0.918, P = 0.005; for dominant model, OR = 0.771, 95%CI: 0.627–0.946, P = 0.013). The subgroup analysis stratified by ethnicity showed that the significant association between the PPARG Pro12Ala polymorphism and EH was only detected in the Asian subgroup. There was no difference in blood pressure values between Ala carriers and non-carriers. For the C161T polymorphism, only 5 studies comprising 1,118 cases and 1,357 controls met the inclusion criteria. The overall results showed that the PPARG C161T polymorphism was not associated with the risk of EH. But in the subgroup analysis, we found that the PPARG C161T polymorphism significantly associated with the risk of EH in the Asian subgroup (for allelic model, OR = 0.719, 95% CI: 0.537–0.963, P = 0.027; for dominant model, OR = 0.653, 95% CI: 0.439–0.972, P = 0.036).

Conclusion

Our meta-analysis suggested that the PPARG polymorphisms might be associated with the risk of EH.

Association of Renalase SNPs rs2296545 and rs2576178 with the Risk of Hypertension: A Meta-Analysis

Background/Aims

Two renalase single nucleotide polymorphisms (SNPs) rs2296545 and rs2576178 have been reported to be associated with the susceptibility to hypertension (HT). Given the inconsistent results, we conducted a meta-analysis to assess the association between these two SNPs and the risk of HT.

Methods

Electronic databases were systematically searched to find relevant studies. Subgroup analysis was conducted according to the different concomitant diseases and ethnicities in the study population. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated using fixed-effect or random-effect models.

Results

A total of six case–control studies on rs2296545 and six studies on rs2576178 were included. In the combined analysis, results showed a significant association between SNP rs2296545 and risk of HT in all genetic models (dominant model CG+CC/GG: OR = 1.43, 95% CI = 1.24–1.65; recessive model CC/CG+GG: OR = 1.36, 95% CI = 1.09–1.69; codominant model CC/GG: OR = 1.63, 95% CI = 1.20–2.20, CG/GG: OR = 1.30, 95% CI = 1.12–1.52; allelic model C/G: OR = 1.29, 95% CI = 1.10–1.51). In subgroup analysis, we observed a significant association between rs2296545 and risk of essential HT. Although we did not observe an association between rs2576178 polymorphism and HT in the combined analysis, an increased risk was observed in the essential HT patients versus healthy controls (subgroup 1) analysis under the dominant, recessive, and codominant genetic models.

Conclusions

Renalase gene rs2296545 polymorphism is significantly associated with increased risk of HT, whereas rs2576178 polymorphism may not be associated with the susceptibility to HT.

The CUL3/KLHL3-WNK-SPAK/OSR1 pathway as a target for antihypertensive therapy

Chronic high blood pressure (hypertension) is the most common disease in the Unites States. While several classes of drugs exist to treat it, many patients (up to 10 million Americans) respond poorly to therapy, even when multiple classes are used. Recent evidence suggests that a significant portion of patients will always remain hypertensive despite maximum therapy with the drugs currently available. Therefore, there is a pressing need to develop novel antihypertensive agents. One limitation has been the identification of new targets, a limitation that has been overcome by recent insights into the mechanisms underlying monogenic forms of hypertension. The disease familial hyperkalemic hypertension is caused by mutations in with-no-lysine (WNK) kinases 1 and 4 and in cullin-3 and kelch-like 3, components of an E3 ubiquitin ligase complex that promotes WNK kinase degradation. The study of the mechanisms by which this pathway regulates blood pressure has identified several candidates for the development of new antihypertensive agents. This pathway is particularly attractive since its inhibition may not only reduce renal sodium reabsorption along multiple segments but may also reduce vascular tone. Here, we will describe the mechanisms by which this pathway regulate blood pressure and discuss the potential of targeting it to develop new antihypertensive drugs.

STK39 and WNK1 Are Potential Hypertension Susceptibility Genes in the BELHYPGEN Cohort

The serine/threonine kinase With-No-Lysine (K) Kinase 1 (WNK1) activates the thiazide-sensitive Na(+)/Cl(-) cotransporter through phosphorylation of STE20/SPS1-related proline/alanine-rich kinase, another serine/threonine kinase encoded by STK39. The aim of this study was to look for association between WNK1 and STK39 gene variants, and blood pressure (BP) and hypertension. Seven hundred seventy-nine Caucasian hypertensive patients (HYP) recruited in 6 academic centers from Belgium, and 906 normotensive (NT) controls were genotyped for 5 single nucleotide polymorphisms-rs3754777, rs6749447, rs35929607 (STK39), rs1468326, and rs765250 (WNK1)-using the Snapshot method. The rare TT genotype at the rs3754777 locus (STK39) was overrepresented in HYP versus NT (7.3% vs 3.0%, P = 0.0002). In the whole study population, the multivariable-adjusted odds ratio (OR) for having hypertension associated with the TT genotype was 5.9 (95% confidence interval: 2.2-15.6), and systolic BP was 10 mm Hg higher in TT compared with wild-type subjects (140.1 vs 130.4 mm Hg, P = 0.002). Similarly, the AA genotype at the rs1468326 locus (WNK1) was twice as frequent in HYP versus NT (5.5% vs 2.3%, P < 0.0001), and associated with an increased adjusted OR of hypertension (4.1; 1.5-11.7) and a higher systolic BP (139.8 vs 130.1 mm Hg, P = 0.003). In the whole cohort, a dose-dependent increase in systolic BP was observed according to the number of at-risk genotypes (0: 129.8 mm Hg; 1: 133.0 mm Hg; 2: 149.3 mm Hg, P = 0.02). Single nucleotide polymorphisms rs3754777 (STK39) and rs1468326 (WNK1) were associated with hypertension and BP in our multicenter Belgian case-control study, which supports the role of STK39 and WNK1 as potential hypertension susceptibility genes. Replication in different clinical settings and study of other candidate loci belonging to the same molecular pathway is warranted.

Recent Advances in the Genetics of Hypertension

Hypertension is a silent killer worldwide, caused by both genetic and environmental factors. Until now, genetic and genomic association studies of hypertension are reporting different degree of association on hypertension. Hence, it is essential to gather all the available information on the reported genetic loci and to determine if any biomarker(s) is/are significantly associated with hypertension. Current review concluded the potential biomarkers for hypertension, with regards to electrolyte and fluid transports, as well as sodium/potassium ions homeostasis, which are supported by the results of case-controls and meta-analyses.

Lack of family-based association between common variations in WNK1 and blood pressure level

BACKGROUND

WNK1 (With No-lysine Kinase 1) modulates numerous sodium transport-related ion channels involved in regulation of blood pressure. Several studies have indicated associations between the common variants of the WNK1 gene and hypertension or blood pressure levels. However, little data exists on Asian populations and normotensive or pre-hypertensive subjects. Our aim was to detect whether the common variations in the WNK1 gene are potential contributors to individual variations in blood pressure in a family-based sample.

MATERIAL AND METHODS

525 individuals from 116 families were selected from a rural community of Northern China. Five single-nucleotide polymorphisms were selected from the WNK1 gene. Single-marker and haplotype analyses were conducted using the Family-Based Association Test program.

RESULTS

Regretful, no associations for the 5 WNK1 SNPs and the constructed haplotype blocks of WNK1 with blood pressure level reached nominal statistical significance.

CONCLUSIONS

We conclude that although multiple candidate genes are involved in development of hypertension, the genetic polymorphism in WNK1 is not a major contributor to the observed variability in blood pressure and familial clustering risk of hypertension.

Comprehensive assessment of the association of WNK4 polymorphisms with hypertension: evidence from a meta-analysis

The relationship between with-no-lysine [K] kinase 4 (WNK4) gene polymorphisms and hypertension has been widely investigated, However, the studies yielded contradictory results. To evaluate these inconclusive findings comprehensively, we therefore performed a meta-analysis. Ten articles encompassing 16 independent case-control studies with 6089 hypertensive cases and 4881 normotensive controls were selected for this meta-analysis. Four WNK4 gene polymorphisms were identified (G1155942T, G1156666A, T1155547C, and C6749T). The results showed statistically significant associations of G1155942T polymorphism (allelic genetic model: odds ration or OR = 1.62, 95% confidence interval or CI: 1.11–2.38, P = 0.01; dominant model: OR = 1.85, 95% CI: 1.07–3.19, P = 0.03) and C6749T polymorphism (allele contrast: OR = 2.04, 95% CI: 1.60–2.59, P<0.01; dominant model: OR = 2.04, 95%CI: 1.59–2.62, P<0.01; and homozygous model: OR = 5.01, 95% CI: 1.29–19.54, P = 0.02) with hypertension risk. However, neither C1155547T nor G1156666A was associated significantly with hypertension susceptibility. In conclusion, this meta-analysis suggested that WNK4 G1155942T and C6749T gene polymorphisms may contribute to the susceptibility and development of hypertension. Further well-designed studies with larger sample size are required to elucidate the association of WNK4 gene multiple polymorphisms with hypertension risk.

Renal sodium transporters are increased in urinary exosomes of cyclosporine-treated kidney transplant patients

BACKGROUND/AIMS

Cyclosporine (CsA) is a calcineurin inhibitor widely used as an immunosuppressant in organ transplantation. Previous studies demonstrated the relationship between CsA and renal sodium transporters such as the Na-K-2Cl cotransporter in the loop of Henle (NKCC2). Experimental models of CsA-induced hypertension have shown an increase in renal NKCC2.

METHODS

Using immunoblotting of urinary exosomes, we investigated in CsA-treated kidney transplant patients (n = 39) the excretion of NKCC2 and Na-Cl cotransporter (NCC) and its association with blood pressure (BP) level. We included 8 non-CsA-treated kidney transplant patients as a control group. Clinical data, immunosuppression and hypertension treatments, blood and 24-hour urine tests, and 24-hour ambulatory BP monitoring were recorded.

RESULTS

CsA-treated patients tended to excrete a higher amount of NKCC2 than non-CsA-treated patients (mean ± SD, 175 ± 98 DU and 90 ± 70.3 DU, respectively; p = 0.05) and showed higher BP values (24-hour systolic BP 138 ± 17 mm Hg and 112 ± 12 mm Hg, p = 0.003; 24-hour diastolic BP, 83.8 ± 9.8 mm Hg and 72.4 ± 5.2 mm Hg, p = 0.015, respectively). Within the CsA-treated group, there was no correlation between either NKCC2 or NCC excretion and BP levels. This was confirmed by a further analysis including potential confounding factors. On the other hand, a significant positive correlation was observed between CsA blood levels and the excretion of NKCC2 and NCC.

CONCLUSION

Overall, these results support the hypothesis that CsA induces an increase in NKCC2 and NCC in urinary exosomes of renal transplant patients. The fact that the increase in sodium transporters in urine did not correlate with the BP level suggests that in kidney transplant patients, other mechanisms could be implicated in CsA-induced hypertension.

Advances in blood pressure genomics

The elucidation of genes implicated in Mendelian forms of hypertension demonstrates rare variants with substantial effects are responsible, and often these genes lie within pathways managing sodium homeostasis. More recently with advances in affordable high-throughput genotyping strategies, multiple common genetic variants with modest effects on blood pressure (<1 mmHg systolic) have been discovered in the population. In aggregate, these common variants explain <3% of the variance of blood pressure. Although these findings may offer new mechanistic insights into the biology of blood pressure, a key question is can these findings translate into patient benefit? It is timely to reflect on recent advances in genomics, and the use of new resources, such as the 1000 Genomes Project and the Encyclopedia of DNA Elements, to annotate likely causal variants, and their relevance to cardiovascular disease. In this review, we discuss the advances in relation to our knowledge of the genetic architecture of blood pressure, and whether gene discoveries might influence cardiovascular risk assessment, help to stratify patient response to medicine, or identify new biological pathways for novel therapeutic targets.

Systems analysis of human brain gene expression: mechanisms for HIV-associated neurocognitive impairment and common pathways with Alzheimer's disease

Background

Human Immunodeficiency Virus-1 (HIV) infection frequently results in neurocognitive impairment. While the cause remains unclear, recent gene expression studies have identified genes whose transcription is dysregulated in individuals with HIV-association neurocognitive disorder (HAND). However, the methods for interpretation of such data have lagged behind the technical advances allowing the decoding genetic material. Here, we employ systems biology methods novel to the field of NeuroAIDS to further interrogate extant transcriptome data derived from brains of HIV + patients in order to further elucidate the neuropathogenesis of HAND. Additionally, we compare these data to those derived from brains of individuals with Alzheimer’s disease (AD) in order to identify common pathways of neuropathogenesis.

Methods

In Study 1, using data from three brain regions in 6 HIV-seronegative and 15 HIV + cases, we first employed weighted gene co-expression network analysis (WGCNA) to further explore transcriptome networks specific to HAND with HIV-encephalitis (HIVE) and HAND without HIVE. We then used a symptomatic approach, employing standard expression analysis and WGCNA to identify networks associated with neurocognitive impairment (NCI), regardless of HIVE or HAND diagnosis. Finally, we examined the association between the CNS penetration effectiveness (CPE) of antiretroviral regimens and brain transcriptome. In Study 2, we identified common gene networks associated with NCI in both HIV and AD by correlating gene expression with pre-mortem neurocognitive functioning.

Results

Study 1: WGCNA largely corroborated findings from standard differential gene expression analyses, but also identified possible meta-networks composed of multiple gene ontology categories and oligodendrocyte dysfunction. Differential expression analysis identified hub genes highly correlated with NCI, including genes implicated in gliosis, inflammation, and dopaminergic tone. Enrichment analysis identified gene ontology categories that varied across the three brain regions, the most notable being downregulation of genes involved in mitochondrial functioning. Finally, WGCNA identified dysregulated networks associated with NCI, including oligodendrocyte and mitochondrial functioning. Study 2: Common gene networks dysregulated in relation to NCI in AD and HIV included mitochondrial genes, whereas upregulation of various cancer-related genes was found.

Conclusions

While under-powered, this study identified possible biologically-relevant networks correlated with NCI in HIV, and common networks shared with AD, opening new avenues for inquiry in the investigation of HAND neuropathogenesis. These results suggest that further interrogation of existing transcriptome data using systems biology methods can yield important information.

Tumor necrosis factor-alpha g308α gene polymorphism and essential hypertension: a meta-analysis involving 2244 participants

Background

The tumor necrosis factor-alpha (TNFα) G308A gene polymorphism has been implicated in susceptibility to essential hypertension (EH), but study results are still controversial.

Objective and Methods

The present meta-analysis is performed to investigate the relationship between the TNFα G308A gene polymorphism and EH. Electronic databases were searched and seven separate studies on the association of the TNF α G308A gene polymorphism with EH were analyzed. The meta-analysis involved 1092 EH patients and 1152 controls. The pooled odds ratios (ORs) and their corresponding 95% confidence interval (CI) were calculated by a fixed or random effect model.

Results

A significant relationship between the TNFα G308A gene polymorphism and EH was found in an allelic genetic model (OR: 1.45, 95% CI: 1.17 to 1.80, P = 0.0008), a recessive genetic model (OR: 3.181, 95% CI: 1.204 to 8.408, P = 0.02), and a homozygote model (OR: 3.454, 95% CI: 1.286 to 9.278, P = 0.014). No significant association between them was detected in both a dominant genetic model (OR: 1.55, 95% CI: 0.99 to 2.42, P = 0.06) or a heterozygote genetic model (OR: 1.45, 95% CI: 0.90 to 2.33, P = 0.13).

Conclusion

The TNFα G308A gene polymorphism is associated with EH susceptibility.

Is the toxicity of anti-angiogenic drugs predictive of outcome? A review of hypertension and proteinuria as biomarkers of response to anti-angiogenic therapy

INTRODUCTION

The prototypic anti-angiogenic agents, VEGF inhibitors, are increasingly used in clinical practice to treat a variety of tumours. Although generally well tolerated, their toxicities can be significant or occasionally life threatening. The ability to identify those patients whose disease will respond to VEGF inhibitors would minimise exposure to ineffective drugs for some patients. To date, there are no validated predictive or prognostic biomarkers for anti-angiogenic drugs. Toxicities such as hypertension and proteinuria are related to the effect of VEGF inhibition on the vasculature. This has led to the investigation of these toxicities as potential biomarkers of clinical outcome in patients treated with these agents.

AREAS COVERED

Putative mechanisms for the development of hypertension and proteinuria, and their potential role as clinically useful biomarkers in relation to anti-angiogenic drugs are discussed in this article. PUBMED, EMBASE and abstracts presented at the American Society of Clinical Oncology until July 2011 were searched to identify relevant English language articles. Studies of anti-angiogenic therapies testing the relationship of either hypertension or proteinuria with outcome were included.

EXPERT OPINION

The evidence in support of the hypothesis that hypertension and proteinuria are biomarkers of response to anti-angiogenic drugs is inconclusive. Current evidence suggests that hypertension is a pharmacodynamic effect of anti-angiogenic agents. Future studies should aim to measure and report toxicities in a standardised manner to facilitate comparisons between studies.

The kidneys and aldosterone/mineralocorticoid receptor system in salt-sensitive hypertension

Strong evidence supports the ability of the aldosterone/mineralocorticoid receptor (MR) system to dominate long-term blood pressure control. It is also increasingly recognized as an important mediator of cardiovascular and renal diseases, particularly in the presence of excessive salt intake. In a subgroup of individuals with metabolic syndrome, adipocyte-derived aldosterone-releasing factors cause inappropriate secretion of aldosterone in the adrenal glands during salt loading, resulting in the development of salt-induced hypertension and cardiac and renal damage. On the other hand, emerging data reveal that aldosterone is not a sole regulator of MR activity. We have identified the signaling crosstalk between MR and small GTPase Rac1 as a novel pathway to facilitate MR signaling. Such a local control system for MR can also be relevant to the pathogenesis of salt-sensitive hypertension, and future studies will clarify the detailed mechanism for the intricate regulation of the aldosterone/MR cascade.

Novel polymorphic AluYb8 insertion in the WNK1 gene is associated with blood pressure variation in Europeans

Mutations in WNK1 and WNK4 cause familial hypertension, the Gordon syndrome. WNK1 and WNK4 conserved noncoding regions were targeted to polymorphism screening using DHPLC and DGGE. The scan identified an undescribed polymorphic AluYb8 insertion in WNK1 intron 10. Screening in primates revealed that this Alu-insertion has probably occurred in human lineage. Genotyping in 18 populations from Europe, Asia, and Africa (n = 854) indicated an expansion of the WNK1 AluYb8 bearing chromosomes out of Africa. The allele frequency in Sub-Saharan Africa was ∼3.3 times lower than in other populations (4.8 vs. 15.8%; P = 9.7 × 10⁻⁹). Meta-analysis across three European sample sets (n = 3,494; HYPEST, Estonians; BRIGHT, the British; CADCZ, Czech) detected significant association of the WNK1 AluYb8 insertion with blood pressure (BP; systolic BP, P = 4.03 × 10⁻³, effect 1.12; diastolic BP, P = 1.21 × 10⁻², effect 0.67). Gender-stratified analysis revealed that this effect might be female-specific (n = 2,088; SBP, P = 1.99 × 10⁻³, effect 1.59; DBP P = 3.64 × 10⁻⁴, effect 1.23; resistant to Bonferroni correction), whereas no statistical support was identified for the association with male BP (n = 1,406). In leucocytes, the expressional proportions of the full-length WNK1 transcript and the splice-form skipping exon 11 were significantly shifted in AluYb8 carriers compared to noncarriers. The WNK1 AluYb8 insertion might affect human BP via altering the profile of alternatively spliced transcripts. Hum Mutat 32:1–9, 2011. © 2011 Wiley-Liss, Inc.

Association of WNK1 exon 1 polymorphisms with essential hypertension in Hani and Yi minorities of China

The association of polymorphisms in exon 1 of the WNK1 gene with essential hypertension in the minority groups of Hani and Yi of China was investigated in the case-control study. The sequence of 1257bp containing the WNK1 gene exon 1 was determined in 1307 individuals (649 essential hypertension subjects and 658 controls) to identify SNPs in Hani and Yi minority groups. Four of eleven previously known SNPs (rs3168640, rs11885, rs11554421 and rs34880640) were identified. The SNP analysis indicated that SNPs rs11885 and rs11554421 were significantly associated with hypertension in both Hani and Yi populations, and rs34880640 was significantly associated with hypertension in Hani but not in Yi population, adjusted for covariates. Haplotype analysis indicated that the haplotype H1 significantly decreased the risk of hypertension in both populations. These results suggested that WNK1 polymorphisms were involved in the predisposition of essential hypertension in Hani and Yi populations and its effects showed a clear population specificity. This finding supported the importance of population specificity in determining the genetic factors associated with diseases and thus disease treatment.

Recent findings in the genetics of blood pressure and hypertension traits

We provide an overview of ongoing discovery efforts in the genetics of blood pressure (BP) and hypertension (HTN) traits. Two large genome-wide association meta-analyses of individuals of European descent were recently published, revealing ~13 new loci for BP traits. Only two of these loci harbor genes in a pathway known to affect BP (CYP17A1 and NPPA/NPPB). Functional variants in these loci are still unknown. Few genome-wide association studies (GWAS) of complex diseases have been published from non-European populations. The study of populations with different evolutionary history and linkage disequilibrium (LD) structure, such as individuals of African ancestry, may provide an opportunity to further narrow these regions to identify the causal gene(s). Several collaborative efforts toward discovery of low-frequency variants and copy number variation for BP traits are currently underway. As evidence for new loci for complex diseases accumulates the assessment of the epidemiologic architecture of these variants in populations assumes higher priority. The impact of public health-relevant contexts such as diet, physical activity, psychosocial factors, and aging has not been examined for most common variants associated with BP.

The WNK kinase network regulating sodium, potassium, and blood pressure

The relationship between renal salt handling and hypertension is intertwined historically. The discovery of WNK kinases (With No lysine = K) now offers new insight to this relationship because WNKs are a crucial molecular pathway connecting hormones such as angiotensin II and aldosterone to renal sodium and potassium transport. To fulfill this task, the WNKs also interact with other important kinases, including serum and glucocorticoid-regulated kinase 1, STE20/SPS1-related, proline alanine-rich kinase, and oxidative stress responsive protein type 1. Collectively, this kinase network regulates the activity of the major sodium and potassium transporters in the distal nephron, including thiazide-sensitive Na-Cl cotransporters and ROMK channels. Here we show how the WNKs modulate ion transport through two distinct regulatory pathways, trafficking and phosphorylation, and discuss the physiologic and clinical relevance of the WNKs in the kidney. This ranges from rare mutations in WNKs causing familial hyperkalemic hypertension to acquired forms of hypertension caused by salt sensitivity or diabetes mellitus. Although many questions remain unanswered, the WNKs hold promise for unraveling the link between salt and hypertension, potentially leading to more effective interventions to prevent cardiorenal damage.

The WNKs: atypical protein kinases with pleiotropic actions

WNKs are serine/threonine kinases that comprise a unique branch of the kinome. They are so-named owing to the unusual placement of an essential catalytic lysine. WNKs have now been identified in diverse organisms. In humans and other mammals, four genes encode WNKs. WNKs are widely expressed at the message level, although data on protein expression is more limited. Soon after the WNKs were identified, mutations in genes encoding WNK1 and -4 were determined to cause the human disease familial hyperkalemic hypertension (also known as pseudohypoaldosteronism II, or Gordon's Syndrome). For this reason, a major focus of investigation has been to dissect the role of WNK kinases in renal regulation of ion transport. More recently, a different mutation in WNK1 was identified as the cause of hereditary sensory and autonomic neuropathy type II, an early-onset autosomal disease of peripheral sensory nerves. Thus the WNKs represent an important family of potential targets for the treatment of human disease, and further elucidation of their physiological actions outside of the kidney and brain is necessary. In this review, we describe the gene structure and mechanisms regulating expression and activity of the WNKs. Subsequently, we outline substrates and targets of WNKs as well as effects of WNKs on cellular physiology, both in the kidney and elsewhere. Next, consequences of these effects on integrated physiological function are outlined. Finally, we discuss the known and putative pathophysiological relevance of the WNKs.

Subtelomeric deletion of 12p: Description of a third case and review

Only 12 cases with a cytogenetically visible deletion of the short arm of chromosome 12 (12p) have been reported so far. The difference in clinical features observed in these patients indicates that there is no distinct phenotype associated with this short arm deletion, although the existence of a del(12p) syndrome was previously suggested. Besides those 12 reports, only two patients have been described with a subtelomeric 12p deletion; both present in the same family in which the son showed a mild phenotype of moderate mental retardation and behavioral problems and his carrier mother had no apparent phenotype. In this article, we describe the third known patient with a subtelomeric 12p deletion in a young boy with mental retardation and microcephaly, and review the literature.

Genetic architecture of complex traits predisposing to nephropathy: hypertension

Blood pressure and hypertension have significant genetic underpinnings that may be age-dependent. The age-dependency, significant contributions from environmental factors such as diet and exercise, and inherent moment-to-moment variability complicate the identification of the genes contributing to the development of hypertension. Although genetic abnormalities may have moderate effects, the physiologic pathways involving these genes have redundant compensating mechanisms to bring the system back into equilibrium. This has the effect of reducing or completely masking the initial genetic defects, one of the hypothesized reasons for the small genetic effects found by the recent genome-wide association studies. This review article discusses the concept of initiators versus compensators in the context of finding genes related to hypertension development. A brief review is provided of some key genes found to be associated with hypertension, including the genes identified from the nine genome-wide association studies published to date.

Signaling mechanisms that link salt retention to hypertension: endogenous ouabain, the Na(+) pump, the Na(+)/Ca(2+) exchanger and TRPC proteins

Salt retention as a result of chronic, excessive dietary salt intake, is widely accepted as one of the most common causes of hypertension. In a small minority of cases, enhanced Na(+) reabsorption by the kidney can be traced to specific genetic defects of salt transport, or pathological conditions of the kidney, adrenal cortex, or pituitary. Far more frequently, however, salt retention may be the result of minor renal injury or small genetic variation in renal salt transport mechanisms. How salt retention actually leads to the increase in peripheral vascular resistance (the hallmark of hypertension) and the elevation of blood pressure remains an enigma. Here we review the evidence that endogenous ouabain (an adrenocortical hormone), arterial smooth muscle α2 Na(+) pumps, type-1 Na/Ca exchangers, and receptor- and store-operated Ca(2+) channels play key roles in the pathway that links salt to hypertension. We discuss cardenolide structure-function relationships in an effort to understand why prolonged administration of ouabain, but not digoxin, induces hypertension, and why digoxin is actually anti-hypertensive. Finally, we summarize recent observations which indicate that ouabain upregulates arterial myocyte Ca(2+) signaling mechanisms that promote vasoconstriction, while simultaneously downregulating endothelial vasodilator mechanisms. In sum, the reports reviewed here provide novel insight into the molecular mechanisms by which salt retention leads to hypertension.

Genetics of hypertension: from experimental animals to humans

Essential hypertension affects 20 to 30% of the population worldwide and contributes significantly to cardiovascular mortality and morbidity. Heridability of blood pressure is around 15 to 40% but there are also substantial environmental factors affecting blood pressure variability. It is assumed that blood pressure is under the control of a large number of genes each of which has only relatively mild effects. It has therefore been difficult to discover the genes that contribute to blood pressure variation using traditional approaches including candidate gene studies and linkage studies. Animal models of hypertension, particularly in the rat, have led to the discovery of quantitative trait loci harbouring one or several hypertension related genes, but translation of these findings into human essential hypertension remains challenging. Recent development of genotyping technology made large scale genome-wide association studies possible. This approach and the study of monogenic forms of hypertension has led to the discovery of novel and robust candidate genes for human essential hypertension, many of which require functional analysis in experimental models.

Variations in the WNK1 gene modulates the effect of dietary intake of sodium and potassium on blood pressure determination

WNK lysine-deficient protein kinase 1 (WNK1) is a member of the WNK family of serine/threonine kinases with no lysine (K), and these kinases have been implicated as important modulators of salt homeostasis in the kidney. It is well known that high dietary sodium and low dietary potassium have been implicated in the etiology of increased blood pressure. However, the blood pressure response to dietary sodium and potassium intake varies considerably among individuals. In this study, we have detected that the haplotypes of the WNK1 gene are associated with blood pressure variations in the general Japanese population. In addition, we investigated the interactions between the haplotypes of the WNK1 gene and dietary sodium and potassium intake for determining inter-individual variations in blood pressure. Our data support the hypothesis that part of the variation in blood pressure response to dietary sodium and potassium intake among individuals can be explained by variations in the WNK1 gene.

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

Elevated blood pressure is a common, heritable cause of cardiovascular disease worldwide. To date, identification of common genetic variants influencing blood pressure has proven challenging. We tested 2.5 million genotyped and imputed SNPs for association with systolic and diastolic blood pressure in 34,433 subjects of European ancestry from the Global BPgen consortium and followed up findings with direct genotyping (N ≤ 71,225 European ancestry, N ≤ 12,889 Indian Asian ancestry) and in silico comparison (CHARGE consortium, N = 29,136). We identified association between systolic or diastolic blood pressure and common variants in eight regions near the CYP17A1 (P = 7 × 10(-24)), CYP1A2 (P = 1 × 10(-23)), FGF5 (P = 1 × 10(-21)), SH2B3 (P = 3 × 10(-18)), MTHFR (P = 2 × 10(-13)), c10orf107 (P = 1 × 10(-9)), ZNF652 (P = 5 × 10(-9)) and PLCD3 (P = 1 × 10(-8)) genes. All variants associated with continuous blood pressure were associated with dichotomous hypertension. These associations between common variants and blood pressure and hypertension offer mechanistic insights into the regulation of blood pressure and may point to novel targets for interventions to prevent cardiovascular disease.

Genomewide association studies of stroke

BACKGROUND

The genes underlying the risk of stroke in the general population remain undetermined.

METHODS

We carried out an analysis of genomewide association data generated from four large cohorts composing the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium, including 19,602 white persons (mean [+/-SD] age, 63+/-8 years) in whom 1544 incident strokes (1164 ischemic strokes) developed over an average follow-up of 11 years. We tested the markers most strongly associated with stroke in a replication cohort of 2430 black persons with 215 incident strokes (191 ischemic strokes), another cohort of 574 black persons with 85 incident strokes (68 ischemic strokes), and 652 Dutch persons with ischemic stroke and 3613 unaffected persons.

RESULTS

Two intergenic single-nucleotide polymorphisms on chromosome 12p13 and within 11 kb of the gene NINJ2 were associated with stroke (P<5x10(-8)). NINJ2 encodes an adhesion molecule expressed in glia and shows increased expression after nerve injury. Direct genotyping showed that rs12425791 was associated with an increased risk of total (i.e., all types) and ischemic stroke, with hazard ratios of 1.30 (95% confidence interval [CI], 1.19 to 1.42) and 1.33 (95% CI, 1.21 to 1.47), respectively, yielding population attributable risks of 11% and 12% in the discovery cohorts. Corresponding hazard ratios were 1.35 (95% CI, 1.01 to 1.79; P=0.04) and 1.42 (95% CI, 1.06 to 1.91; P=0.02) in the large cohort of black persons and 1.17 (95% CI, 1.01 to 1.37; P=0.03) and 1.19 (95% CI, 1.01 to 1.41; P=0.04) in the Dutch sample; the results of an underpowered analysis of the smaller black cohort were nonsignificant.

CONCLUSIONS

A genetic locus on chromosome 12p13 is associated with an increased risk of stroke.

Polymorphisms in the WNK1 gene are associated with blood pressure variation and urinary potassium excretion

WNK1 - a serine/threonine kinase involved in electrolyte homeostasis and blood pressure (BP) control - is an excellent candidate gene for essential hypertension (EH). We and others have previously reported association between WNK1 and BP variation. Using tag SNPs (tSNPs) that capture 100% of common WNK1 variation in HapMap, we aimed to replicate our findings with BP and to test for association with phenotypes relating to WNK1 function in the British Genetics of Hypertension (BRIGHT) study case-control resource (1700 hypertensive cases and 1700 normotensive controls). We found multiple variants to be associated with systolic blood pressure, SBP (7/28 tSNPs min-p = 0.0005), diastolic blood pressure, DBP (7/28 tSNPs min-p = 0.002) and 24 hour urinary potassium excretion (10/28 tSNPs min-p = 0.0004). Associations with SBP and urine potassium remained significant after correction for multiple testing (p = 0.02 and p = 0.01 respectively). The major allele (A) of rs765250, located in intron 1, demonstrated the strongest evidence for association with SBP, effect size 3.14 mmHg (95%CI:1.23–4.9), DBP 1.9 mmHg (95%CI:0.7–3.2) and hypertension, odds ratio (OR: 1.3 [95%CI: 1.0–1.7]).We genotyped this variant in six independent populations (n = 14,451) and replicated the association between rs765250 and SBP in a meta-analysis (p = 7×10⁻³, combined with BRIGHT data-set p = 2×10⁻⁴, n = 17,851). The associations of WNK1 with DBP and EH were not confirmed. Haplotype analysis revealed striking associations with hypertension and BP variation (global permutation p<10⁻⁷). We identified several common haplotypes to be associated with increased BP and multiple low frequency haplotypes significantly associated with lower BP (>10 mmHg reduction) and risk for hypertension (OR<0.60). Our data indicates that multiple rare and common WNK1 variants contribute to BP variation and hypertension, and provide compelling evidence to initiate further genetic and functional studies to explore the role of WNK1 in BP regulation and EH.

The genetics of cardiovascular disease

Recent advances in genotyping technology and insights into disease mechanisms have increased interest in the genetics of cardiovascular disease. Several candidate genes involved in cardiovascular diseases were identified from studies using animal models, and the translation of these findings to human disease is an exciting challenge. There is a trend towards large-scale genome-wide association studies that are subject to strict quality criteria with regard to both genotyping and phenotyping. Here, we review some of the strategies that have been developed to translate findings from experimental models to human disease and outline the need for optimizing global approaches to analyze such results. Findings from ongoing studies are interpreted in the context of disease pathways instead of the more traditional focus on single genetic variants.

Common Variation in the WNK1 Gene and Blood Pressure in Childhood

WNK1 gene variants have been associated with adult blood pressure. We aimed to investigate relationships between WNK1 variants and blood pressure, as well as blood pressure change with age, in a longitudinal childhood study. Associations between single nucleotide polymorphisms in WNK1 and blood pressure and the rate of blood pressure change between 7 and 11 years were examined in the Avon Longitudinal Study of Parent and Children Study (n=5326 for systolic blood pressure at 11 years). We observed associations ( P <0.05) with diastolic blood pressure gradient with age for 33 of 82 typed and imputed polymorphisms, including polymorphisms in exons 4, 10, and 11 (rs10774466, rs1012729, and rs9804992). The minor allele (G) of rs1012729 (frequency: 25.6%) was associated with a gender-adjusted change in a diastolic blood pressure gradient of −0.11 mm Hg/y (95% CI: −0.20 to −0.03 mm Hg/y; P =0.0054). No associations were shown with the systolic blood pressure gradient. At age 11 years, 30 polymorphisms showed association ( P <0.05) with systolic blood pressure, including variants in exons 4 and 10 (rs10774466 and rs1012729). Only 3 polymorphisms were associated with diastolic blood pressure at 11 years. In exploration of polymorphism-dietary cation interactions on systolic blood pressure at 11 years, 59 reached significance ( P <0.05; 12.3 expected by chance), mostly (n=33) related to dietary calcium. The findings show that common intronic and exonic WNK1 variants are associated with diastolic blood pressure gradient from 7 to 11 years and with systolic blood pressure at 11 years. Our study suggests that previously reported effects of WNK1 variants on blood pressure are mediated via effects on the gradient of blood pressure change with age.