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

L-GATOR: Genetic Association Testing for a Longitudinally Measured Quantitative Trait in Samples with Related Individuals

In complex-trait mapping, when each subject has multiple measurements of a quantitative trait over time, power for detecting genetic association can be gained by the inclusion of all measurements and not just single time points or averages in the analysis. To increase power and control type 1 error, one should account for dependence among observations for a single individual as well as dependence between observations of related individuals if they are present in the sample. We propose L-GATOR, a retrospective, mixed-effects method for association mapping of longitudinally measured traits in samples with related individuals. L-GATOR allows arbitrary time points for different individuals, incorporates both time-varying and static covariates, and properly addresses various types of dependence. In simulations, we show that L-GATOR outperforms existing prospective methods in terms of both type 1 error and power when there is phenotype model misspecification or missing data. Compared with the previously proposed longGWAS method, L-GATOR was more than ten times faster for association testing in our simulations and almost 100 times faster for parameter estimation. L-GATOR is applicable to essentially arbitrary combinations of related and unrelated individuals, including small families as well as large, complex pedigrees. We apply the method to data from the Framingham Heart Study to identify association between longitudinal systolic blood pressure measurements and genome-wide SNPs. Of the smallest p values, one-third occur in or near genes that have been previously identified as associated with pulse pressure (such as PIK3CG) and systolic and diastolic blood pressure (such as C10orf107), showing that L-GATOR is able to prioritize relevant loci in a genome screen.

The Critical Role of Inflammation in the Pathogenesis and Progression of Myeloid Malignancies

Hematopoietic stem cells (HSCs) maintain an organism's immune system for a lifetime, and derangements in HSC proliferation and differentiation result in hematologic malignancies. Chronic inflammation plays a contributory if not causal role in HSC dysfunction. Inflammation induces HSC exhaustion, which promotes the emergence of mutant clones that may be resistant to an inflammatory microenvironment; this likely promotes the onset of a myeloid hematologic malignancy. Inflammatory cytokines are characteristically high in patients with myeloid malignancies and are linked to disease initiation, symptom burden, disease progression, and worsened prognostic survival. This review will cover our current understanding of the role of inflammation in the initiation, progression, and complications of myeloid hematologic malignancies, drawing from clinical studies as well as murine models. We will also highlight inflammation as a therapeutic target in hematologic malignancies.

Hypertension and Cerebral Microangiopathy (Cerebral Small Vessel Disease): Genetic and Epigenetic Aspects of Their Relationship

Hypertension (HT) and its cerebral complications are extremely vexing medical and social problems. Despite the obvious association between hypertension and the clinical and neuroimaging features of cerebral microangiopathy (CMA) (also known as cerebral small vessel disease), the causal links between them remain ambiguous. Besides, antihypertensive therapy as the only way to manage these patients does not always prevent brain damage. Knowledge about the key factors and mechanisms involved in HT and CMA development is important for predicting the risk of cerebral complications and developing new approaches to their prevention and treatment. At present, genome-wide association studies and other approaches are used to investigate the common hereditary mechanisms of HT and CMA development, which will explain a large number of CMA cases not associated with hypertension, lack of a correlation between HT severity and the degree of cerebral injury, and failure of antihypertensive therapy to prevent CMA progression. Epigenetic markers likely play a modulating role in the development of these diseases.

Common variant rs11191548 near the CYP17A1 gene is associated with hypertension and the serum 25(OH) D levels in Han Chinese

The CYP17A1 gene, which encodes17α-hydroxylase and 17,20-lyase, has been identified as a common hypertension susceptibility locus in a European population. However, the association between CYP17A1 polymorphisms and hypertension is unclear in the Chinese population as well as in the role of serum 25(OH) D levels. Six single nucleotide polymorphisms (SNPs) in CYP17A1 were genotyped in two stages in a Han Chinese population, and the serum 25(OH) D levels were measured. Analysis in stage 1 showed that the rs1004467 minor G-allele and rs11191548 minor C-allele in CYP17A1 were significantly associated with a decreased risk of hypertension and higher serum 25(OH) D levels (all P < 0.05). The larger sample in stage 2 also showed that a mutation in rs11191548 was significantly associated with a decreased risk of hypertension (adjusted OR = 0.707, 95% CI: 0.553-0.904, P = 0.006). The rs11191548 minor C-allele was associated with higher serum 25(OH) D levels in hypertensive subjects (βadj ± SEM = 0.094 ± 0.949, P = 0.003) and controls (βadj ± SEM = 0.128 ± 1.025, P < 0.001). In conclusion, the rs11191548 CYP17A1 gene mutation was associated with hypertension and the serum 25(OH) D levels in Han Chinese.

A Large-Scale Multi-ancestry Genome-wide Study Accounting for Smoking Behavior Identifies Multiple Significant Loci for Blood Pressure

Genome-wide association analysis advanced understanding of blood pressure (BP), a major risk factor for vascular conditions such as coronary heart disease and stroke. Accounting for smoking behavior may help identify BP loci and extend our knowledge of its genetic architecture. We performed genome-wide association meta-analyses of systolic and diastolic BP incorporating gene-smoking interactions in 610,091 individuals. Stage 1 analysis examined ∼18.8 million SNPs and small insertion/deletion variants in 129,913 individuals from four ancestries (European, African, Asian, and Hispanic) with follow-up analysis of promising variants in 480,178 additional individuals from five ancestries. We identified 15 loci that were genome-wide significant (p < 5 × 10-8) in stage 1 and formally replicated in stage 2. A combined stage 1 and 2 meta-analysis identified 66 additional genome-wide significant loci (13, 35, and 18 loci in European, African, and trans-ancestry, respectively). A total of 56 known BP loci were also identified by our results (p < 5 × 10-8). Of the newly identified loci, ten showed significant interaction with smoking status, but none of them were replicated in stage 2. Several loci were identified in African ancestry, highlighting the importance of genetic studies in diverse populations. The identified loci show strong evidence for regulatory features and support shared pathophysiology with cardiometabolic and addiction traits. They also highlight a role in BP regulation for biological candidates such as modulators of vascular structure and function (CDKN1B, BCAR1-CFDP1, PXDN, EEA1), ciliopathies (SDCCAG8, RPGRIP1L), telomere maintenance (TNKS, PINX1, AKTIP), and central dopaminergic signaling (MSRA, EBF2).

Genome-wide association study of maternal genetic effects and parent-of-origin effects on food allergy

Previous genetic studies of food allergy (FA) have mainly focused on inherited genotypic effects. The role of parental genotypic effects remains largely unexplored. Leveraging existing genome-wide association study (GWAS) data generated from the Chicago Food Allergy Study, we examined maternal genotypic and parent-of-origin (PO) effects using multinomial likelihood ratio tests in 588 complete and incomplete Caucasian FA trios. We identified 1 single nucleotide polymorphism with significant (P < 5×10) maternal effect on any FA (rs4235235), which is located in a noncoding RNA (LOC101927947) with unknown function. We also identified 3 suggestive (P < 5×10) loci with maternal genetic effects: 1 for any FA (rs976078, in a gene desert region on 13q31.1) and 2 for egg allergy (rs1343795 and rs4572450, in the ZNF652 gene, where genetic variants have been associated with atopic dermatitis). Three suggestive loci with PO effect were observed: 1 for peanut allergy (rs4896888 in the ADGB gene) and 2 for any FA in boys only (rs1036504 and rs2917750 in the IQCE gene). Findings from this family-based GWAS of FA provided some preliminary evidence on maternal genotypic or PO effects on FA. Additional family-based studies are needed to confirm our findings and gain new insight into maternal and paternal genetic contribution to FA.

ATP2B1 rs2681472 and STK39 rs35929607 polymorphisms and risk of Hypertension in Iranian Population

Background: ATP2B1 and STK39 have been introduced as essential hypertension candidate genes. The association of these genes' variations have not been studied in Iranian population yet. Here we aimed to investigate the association of ATP2B1 rs2681472 and STK39 rs35929607 polymorphisms with the risk of hypertension in an Iranian population. Methods: We included 400 individuals in our case-control study: 200 cases with essential hypertension and 200 healthy sex and age matched controls. All subjects were genotyped for rs2681472 and rs35929607 using a PCR-RFLP method. Genotype and allele frequencies were compared between the two groups using chi-squared test. The association was further assessed under log-additive, dominant and recessive genetic models. Results: There was no association between rs2681472 and rs35929607 polymorphisms and risk of essential hypertension in our population (p>0.05). There was also no association between the studied polymorphisms and hypertension under different genetic models. Conclusion: Our study indicated that rs2681472 of ATP2B1 and rs35929607 of STK39 may not have a significant effect on the risk of essential hypertension in Iranian population. More studies are still needed to validate our results.

Associations of the hypertension-related single nucleotide polymorphism rs11191548 with high-density lipoprotein cholesterol and leptin in Chinese children

Background

The genome-wide association study has founded hypertension-related single nucleotide polymorphism (SNP) rs11191548 near CYP17A1 encoding a key enzyme involved in steroid metabolism, but the molecular mechanisms are not understood and the associations of the SNP with hypertension-related traits are not fully described, especially in children. The aim of the present study is to investigate the associations between the SNP and two hypertension-related traits, lipids and leptin.

Methods

We genotyped the SNP in Beijing Child and Adolescent Metabolic Syndrome (BCAMS) study. A total of 3503 children participated in the study.

Results

The SNP rs11191548 was significantly associated with high-density lipoprotein cholesterol (HDL) (P = 0.014 and 0.028, respectively) and leptin (P = 0.011 and 0.026, respectively) under an additive model after adjustment for age, gender, and systolic blood pressure (SBP) or diastolic blood pressure (DBP). There was a statistically significant association of rs11191548 with high leptin after adjustment for age, gender, and SBP or DBP. The P-values remain significant after correction for multiple testing.

Conclusions

We demonstrate for the first time that the SNP rs11191548 near CYP17A1 is associated with HDL and leptin in Chinese children. These novel findings provide important evidence that HDL and leptin maybe possibly mediate the process of CYP17A1 involved in hypertension.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0523-y) contains supplementary material, which is available to authorized users.

Looking for new diagnostic tools and biomarkers of hypertension in obese pediatric patients

INTRODUCTION

Development of obesity in childhood may be linked to an increased risk of hypertension.

OBJECTIVES

This study aimed (a) to analyze the expression of genes associated with blood pressure (BP) in obese children, (b) to evaluate ambulatory blood pressure monitoring (ABPM) as a diagnostic tool in hypertension in children, and (c) to assess the prevalence of metabolic syndrome in children with obesity.

PATIENTS AND METHODS

Office BP measurements and ABPM were performed in 49 children with obesity and 25 age-matched healthy children. Expressions of 12 monogenic hypertension genes and 45 genes variants associated with BP were assessed using the microarray technique.

RESULTS

No significant differences in gene expression levels were found. Children with obesity had significantly higher (P<0.001) mean office systolic and diastolic BPs compared with the controls. The diagnosis of high normal BP and hypertension with ABPM was established in 27 and 33% of children, respectively. Nocturnal BP decrease less than 10% was found in 27% of children, whereas nocturnal BP decrease more than 20% was found in 13% of children. Nocturnal BP increase was found in 13% of patients. The diagnosis of metabolic syndrome was established in 29% of obese patients.

CONCLUSION

The following can be concluded: (a) the prevalence of metabolic syndrome was found in nearly one-third of children with obesity. (b) ABPM is a useful and reliable tool in the diagnostics of pediatric hypertension. Abnormal BP can be observed in ∼50% of obese children.

Riboflavin and health: A review of recent human research

There has lately been a renewed interest in Riboflavin owing to insight into its recognition as an essential component of cellular biochemistry. The knowledge of the mechanisms and regulation of intestinal absorption of riboflavin and its health implications has significantly been expanded in recent years. The purpose of this review is to provide an overview of the importance of riboflavin, its absorption and metabolism in health and diseased conditions, its deficiency and its association with various health diseases, and metabolic disorders. Efforts have been made to review the available information in literature on the relationship between riboflavin and various clinical abnormalities. The role of riboflavin has also been dealt in the prevention of a wide array of health diseases like migraine, anemia, cancer, hyperglycemia, hypertension, diabetes mellitus, and oxidative stress directly or indirectly. The riboflavin deficiency has profound effect on iron absorption, metabolism of tryptophan, mitochondrial dysfunction, gastrointestinal tract, brain dysfunction, and metabolism of other vitamins as well as is associated with skin disorders. Toxicological and photosensitizing properties of riboflavin make it suitable for biological use, such as virus inactivation, excellent photosensitizer, and promising adjuvant in chemo radiotherapy in cancer treatment. A number of recent studies have indicated and highlighted the cellular processes and biological effects associated with riboflavin supplementation in metabolic diseases. Overall, a deeper understanding of these emerging roles of riboflavin intake is essential to design better therapies for future.

Pharmacogenomic studies of hypertension: paving the way for personalized antihypertensive treatment

Introduction

Increasing clinical evidence supports the implementation of genotyping for anti-hypertensive drug dosing and selection. Despite robust evidence gleaned from clinical trials, the translation of genotype guided therapy into clinical practice faces significant challenges. Challenges to implementation include the small effect size of individual variants and the polygenetic nature of antihypertensive drug response, a lack of expert consensus on dosing guidelines even without genetic information, and proper definition of major antihypertensive drug toxicities. Balancing clinical benefit with cost, while overcoming these challenges, remains crucial.

Areas covered

This review presents the most impactful clinical trials and cohorts which continue to inform and guide future investigation. Variants were selected from among those identified in the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR), the Genetic Epidemiology of Responses to Antihypertensives study (GERA), the Genetics of Drug Responsiveness in Essential Hypertension (GENRES) study, the SOPHIA study, the Milan Hypertension Pharmacogenomics of hydro-chlorothiazide (MIHYPHCTZ), the Campania Salute Network, the International Verapamil SR Trandolapril Study (INVEST), the Nordic Diltiazem (NORDIL) Study, GenHAT, and others.

Expert Commentary

The polygenic nature of antihypertensive drug response is a major barrier to clinical implementation. Further studies examining clinical effectiveness are required to support broad-based implementation of genotype-based prescribing in medical practice.

Cardiovascular Effects of Renal Distal Tubule Deletion of the FGF Receptor 1 Gene

The bone-derived hormone fibroblast growth factor-23 (FGF-23) activates complexes composed of FGF receptors (FGFRs), including FGFR1, and α-Klotho in the kidney distal tubule (DT), leading to increased sodium retention and hypertension. However, the role of FGFR1 in regulating renal processes linked to hypertension is unclear. Here, we investigated the effects of selective FGFR1 loss in the DT. Conditional knockout (cKO) of FGFR1 in the DT (FGFR1DT-cKO mice) resulted in left ventricular hypertrophy (LVH) and decreased kidney expression of α-Klotho in association with enhanced BP, decreased expression of angiotensin converting enzyme 2, and increased expression of the Na+-K+-2Cl- cotransporter. Notably, recombinant FGF-23 administration similarly decreased the kidney expression of α-Klotho and induced LVH in mice. Pharmacologic activation of FGFR1 with a monoclonal anti-FGFR1 antibody (R1MAb1) normalized BP and significantly attenuated LVH in the Hyp mouse model of excess FGF-23, but did not induce a response in FGFR1DT-cKO mice. The hearts of FGFR1DT-cKO mice showed increased expression of the transient receptor potential cation channel, subfamily C, member 6 (TRPC6), consistent with cardiac effects of soluble Klotho deficiency. Moreover, administration of recombinant soluble Klotho lowered BP in the Hyp mice. Thus, FGFR1 in the DT regulates systemic hemodynamic responses opposite to those predicted by the actions of FGF-23. These cardiovascular effects appear to be mediated by paracrine FGF control of kidney FGFR1 and subsequent regulation of soluble Klotho and TRPC6. FGFR1 in the kidney may provide a new molecular target for treating hypertension.

Brief Overview of a Decade of Genome-Wide Association Studies on Primary Hypertension

Primary hypertension is widely believed to be a complex polygenic disorder with the manifestation influenced by the interactions of genomic and environmental factors making identification of susceptibility genes a major challenge. With major advancement in high-throughput genotyping technology, genome-wide association study (GWAS) has become a powerful tool for researchers studying genetically complex diseases. GWASs work through revealing links between DNA sequence variation and a disease or trait with biomedical importance. The human genome is a very long DNA sequence which consists of billions of nucleotides arranged in a unique way. A single base-pair change in the DNA sequence is known as a single nucleotide polymorphism (SNP). With the help of modern genotyping techniques such as chip-based genotyping arrays, thousands of SNPs can be genotyped easily. Large-scale GWASs, in which more than half a million of common SNPs are genotyped and analyzed for disease association in hundreds of thousands of cases and controls, have been broadly successful in identifying SNPs associated with heart diseases, diabetes, autoimmune diseases, and psychiatric disorders. It is however still debatable whether GWAS is the best approach for hypertension. The following is a brief overview on the outcomes of a decade of GWASs on primary hypertension.

Blood Pressure Control by a Secreted FGFBP1 (Fibroblast Growth Factor-Binding Protein)

Fibroblast growth factors (FGFs) participate in organ development and tissue maintenance, as well as the control of vascular function. The paracrine-acting FGFs are stored in the extracellular matrix, and their release is controlled by a secreted FGF-binding protein (FGF-BP, FGFBP1, and BP1) that modulates FGF receptor signaling. A genetic polymorphism in the human FGFBP1 gene was associated with higher gene expression and an increased risk of familial hypertension. Here, we report on the effects of inducible BP1 expression in a transgenic mouse model. Induction of BP1 expression in adult animals leads to a sustained rise in mean arterial pressure by >30 mm Hg. The hypertensive effect of BP1 expression is prevented by candesartan, an angiotensin II (AngII) receptor antagonist, or by tempol, an inhibitor of reactive oxygen species. In vivo, BP1 expression sensitizes peripheral resistance vessels to AngII constriction by 20-fold but does not alter adrenergic vasoconstriction. FGF receptor kinase inhibition reverses the sensitization to AngII. Also, constriction of isolated renal afferent arterioles by AngII is enhanced after BP1 expression and blocked by FGF receptor kinase inhibition. Furthermore, AngII-mediated constriction of renal afferent arterioles is abolished in FGF2-/- mice but can be restored by add-back of FGF2 plus BP1 proteins. In contrast to AngII, adrenergic constriction is not affected in the FGF2-/- model. Proteomics and gene expression analysis of kidney tissues after BP1 induction show that MAPK (mitogen-activated protein kinase) signaling via MKK4 (MAPK kinase 4), p38, and JNK (c-Jun N-terminal kinase) integrates the crosstalk of the FGF receptor and AngII pathways and thus impact vascular tone and blood pressure.

Csk Regulates Blood Pressure by Controlling the Synthetic Pathways of Aldosterone

BACKGROUND

Blood pressure is regulated by a network of diverse physiological pathways. The C-terminal Src kinase (CSK) locus (15q24) is associated with blood pressure in various ethnic groups. It was recently reported thatCskinsufficiency increases blood pressure through Src. The mechanisms of hypertension inCsk+/-mice are examined further in this study.

METHODS AND RESULTS

To identify a causal component responsible for hypertension inCsk+/-, the heart rate was measured by electrocardiogram and plasma volume by Evans blue dilution. Plasma volume increased inCsk+/-compared with wild-types, while the heart rate did not change. Plasma sodium and aldosterone levels rose consistently inCsk+/-vs. wild-types, and spironolactone, a mineralocorticoid receptor antagonist, reduced blood pressure. The amounts of Sgk1 and Na+/K+-ATPase (NKA) increased in the kidney ofCsk+/-compared with wild-types. It was also found that Cyp11b2 (aldosterone synthase) was upregulated in the adrenal glands ofCsk+/-, and that Csk was enriched in the zona glomerulosa of adrenals, the major site of aldosterone production in the normal mouse.

CONCLUSIONS

The results of the present study identify a physiological pathway by which blood pressure is regulated, in which the insufficiency ofCskinduces aldosterone production with zonal specificity in the adrenal glands, increasing sodium reabsorption and plasma volume and thus resulting in hypertension.

Longitudinal exome-wide association study to identify genetic susceptibility loci for hypertension in a Japanese population

Genome-wide association studies have identified various genetic variants associated with complex disorders. However, these studies have commonly been conducted in a cross-sectional manner. Therefore, we performed a longitudinal exome-wide association study (EWAS) in a Japanese cohort. We aimed to identify genetic variants that confer susceptibility to hypertension using ~244 000 single-nucleotide variants (SNVs) and physiological data from 6026 Japanese individuals who underwent annual health check-ups for several years. After quality control, the association of hypertension with SNVs was tested using a generalized estimating equation model. Finally, our longitudinal EWAS detected seven hypertension-related SNVs that passed strict criteria. Among these variants, six SNVs were densely located at 12q24.1, and an East Asian-specific motif (haplotype) 'CAAAA' comprising five derived alleles was identified. Statistical analyses showed that the prevalence of hypertension in individuals with the East Asian-specific haplotype was significantly lower than that in individuals with the common haplotype 'TGGGT'. Furthermore, individuals with the East Asian haplotype may be less susceptible to the adverse effects of smoking on hypertension. The longitudinal EWAS for the recessive model showed that a novel SNV, rs11917356 of COL6A5, was significantly associated with systolic blood pressure, and the derived allele at the SNV may have spread throughout East Asia in recent evolutionary time.

DNA Methylation Analysis Identifies Loci for Blood Pressure Regulation

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

Genome-Wide Gene-Potassium Interaction Analyses on Blood Pressure: The GenSalt Study (Genetic Epidemiology Network of Salt Sensitivity)

BACKGROUND

Gene-environmental interaction analysis can identify novel genetic factors for blood pressure (BP). We performed genome-wide analyses to identify genomic loci that interact with potassium to influence BP using single-marker (1 and 2 df joint tests) and gene-based tests among Chinese participants of the GenSalt study (Genetic Epidemiology Network of Salt Sensitivity).

METHODS AND RESULTS

Among 1876 GenSalt participants, the average of 3 urine samples was used to estimate potassium excretion. Nine BP measurements were taken using a random-zero sphygmomanometer. A total of 2.2 million single nucleotide polymorphisms were imputed using Affymetrix 6.0 genotype data and the Chinese Han of Beijing and Japanese of Tokyo HapMap reference panel. Promising findings (P<1.00×10-4) from GenSalt were evaluated for replication among 775 Chinese participants of the MESA (Multi-ethnic Study of Atherosclerosis). Single nucleotide polymorphism and gene-based results were meta-analyzed across the GenSalt and MESA studies to determine genome-wide significance. The 1 df tests identified interactions for ARL15 rs16882447 on systolic BP (P=2.83×10-9) and RANBP3L rs958929 on pulse pressure (P=1.58×10-8). The 2 df tests confirmed the ARL15 rs16882447 signal for systolic BP (P=1.15×10-9). Genome-wide gene-based analysis identified CC2D2A (P=2.59×10-7) at 4p15.32 and BNC2 (P=4.49×10-10) at 9p22.2 for systolic BP, GGNBP1 (P=1.18×10-8), and LINC00336 (P=1.36×10-8) at 6p21 for diastolic BP, DAB1 (P=1.05×10-13) at 1p32.2, and MIR4466 (P=5.34×10-8) at 6q25.3 for pulse pressure. The BNC2 (P=3.57×10-8) gene was also significant for mean arterial pressure.

CONCLUSIONS

We identified 2 novel BP loci and 6 genes through the examination of single nucleotide polymorphism- and gene-based interactions with potassium.

Admixture mapping in the Hispanic Community Health Study/Study of Latinos reveals regions of genetic associations with blood pressure traits

Admixture mapping can be used to detect genetic association regions in admixed populations, such as Hispanics/Latinos, by estimating associations between local ancestry allele counts and the trait of interest. We performed admixture mapping of the blood pressure traits systolic and diastolic blood pressure (SBP, DBP), mean arterial pressure (MAP), and pulse pressure (PP), in a dataset of 12,116 participants from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Hispanics/Latinos have three predominant ancestral populations (European, African, and Amerindian), for each of which we separately tested local ancestry intervals across the genome. We identified four regions that were significantly associated with a blood pressure trait at the genome-wide admixture mapping level. A 6p21.31 Amerindian ancestry association region has multiple known associations, but none explained the admixture mapping signal. We identified variants that completely explained this signal. One of these variants had p-values of 0.02 (MAP) and 0.04 (SBP) in replication testing in Pima Indians. A 11q13.4 Amerindian ancestry association region spans a variant that was previously reported (p-value = 0.001) in a targeted association study of Blood Pressure (BP) traits and variants in the vitamin D pathway. There was no replication evidence supporting an association in the identified 17q25.3 Amerindian ancestry association region. For a region on 6p12.3, associated with African ancestry, we did not identify any candidate variants driving the association. It may be driven by rare variants. Whole genome sequence data may be necessary to fine map these association signals, which may contribute to disparities in BP traits between diverse populations.

Parental and offspring contribution of genetic markers of adult blood pressure in early life: The FAMILY study

Previous genome wide association studies (GWAS) identified associations of multiple common variants with diastolic and systolic blood pressure traits in adults. However, the contribution of these loci to variations of blood pressure in early life is unclear. We assessed the child and parental contributions of 33 GWAS single-nucleotide polymorphisms (SNPs) for blood pressure in 1,525 participants (515 children, 406 mothers and 237 fathers) of the Family Atherosclerosis Monitoring In early life (FAMILY) study followed-up for 5 years. Two genotype scores for systolic (29 SNPs) and diastolic (24 SNPs) blood pressure were built. Linear mixed-effect regressions showed significant association between rs1378942 in CSK and systolic blood pressure (β = 0.98±0.46, P = 3.4×10⁻²). The child genotype scores for diastolic and systolic blood pressure were not associated in children. Nominally significant parental genetic effects were found between the SNPs rs11191548 (CYP17A1) (paternal, β = 2.78±1.49, P = 6.1×10⁻² for SBP and β = 3.60±1.24, P = 3.7×10⁻³ for DBP), rs17367504 (MTHFR) (paternal, β = 2.42±0.93, P = 9.3×10⁻³ for SBP and β = 1.89±0.80, P = 1.8×10⁻² for DBP and maternal, β = -1.32±0.60, P = 2.9×10⁻² and β = -1.97±0.77, P = 1.0×10⁻², for SBP and DBP respectively) and child blood pressure. Our study supports the view that adult GWAS loci have a limited impact on blood pressure during the five first years of life. The parental genetic effects observed on blood pressure in children may suggest epigenetic mechanisms in the transmission of the risk of hypertension. Further replication is needed to confirm our results.

Towards precision nephrology: the opportunities and challenges of genomic medicine

The expansion of genomic medicine is furthering our understanding of many human diseases. This is well illustrated in the field of nephrology, through the characterization, discovery, and growing insight into various renal diseases through use of Next Generation Sequencing (NGS) technologies. This review will provide an overview of the diagnostic opportunities of using genetic testing in the clinical setting by describing notable discoveries regarding inherited forms of renal disease that have advanced the field and by highlighting some of the potential benefits of establishing a molecular diagnosis in a clinical practice. In addition, it will discuss some of the challenges associated with the expansion of genetic testing into the clinical setting, including clinical variant interpretation and return of genetic results.

Genetics of NO Deficiency

The nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway plays a key role in regulating cardiovascular homeostasis, and genetic variants allocated to NO-cGMP pathway genes, leading to NO-cGMP deficiency, may influence the prevalence or course of cardiovascular disease. NO-cGMP deficiency can be caused by nitric oxide synthase substrate deficiency, substrate competition, defects, or uncoupling; endogenous inhibitors of nitric oxide synthase; decreased cGMP production; or increased cGMP degradation. This review presents evidence supporting the role of NO-cGMP deficiency in cardiovascular disease, including findings from genetic association studies for particular polymorphisms, haplotypes, and racial disparities. NO-cGMP pathway components including arginases, guanosine-5'-triphosphate cyclohydrolase 1, nitric oxide synthase, dimethylarginine dimethylaminohydrolases, soluble guanylyl cyclase, protein kinase G, phosphodiesterase 5, and natriuretic peptides will be discussed.

Multiphenotype association study of patients randomized to initiate antiretroviral regimens in AIDS Clinical Trials Group protocol A5202

Supplemental Digital Content is available in the text.

Background

High-throughput approaches are increasingly being used to identify genetic associations across multiple phenotypes simultaneously. Here, we describe a pilot analysis that considered multiple on-treatment laboratory phenotypes from antiretroviral therapy-naive patients who were randomized to initiate antiretroviral regimens in a prospective clinical trial, AIDS Clinical Trials Group protocol A5202.

Participants and methods

From among 5 9545 294 polymorphisms imputed genome-wide, we analyzed 2544, including 2124 annotated in the PharmGKB, and 420 previously associated with traits in the GWAS Catalog. We derived 774 phenotypes on the basis of context from six variables: plasma atazanavir (ATV) pharmacokinetics, plasma efavirenz (EFV) pharmacokinetics, change in the CD4+ T-cell count, HIV-1 RNA suppression, fasting low-density lipoprotein-cholesterol, and fasting triglycerides. Permutation testing assessed the likelihood of associations being by chance alone. Pleiotropy was assessed for polymorphisms with the lowest P-values.

Results

This analysis included 1181 patients. At P less than 1.5×10⁻⁴, most associations were not by chance alone. Polymorphisms with the lowest P-values for EFV pharmacokinetics (CYPB26 rs3745274), low-density lipoprotein -cholesterol (APOE rs7412), and triglyceride (APOA5 rs651821) phenotypes had been associated previously with those traits in previous studies. The association between triglycerides and rs651821 was present with ATV-containing regimens, but not with EFV-containing regimens. Polymorphisms with the lowest P-values for ATV pharmacokinetics, CD4 T-cell count, and HIV-1 RNA phenotypes had not been reported previously to be associated with that trait.

Conclusion

Using data from a prospective HIV clinical trial, we identified expected genetic associations, potentially novel associations, and at least one context-dependent association. This study supports high-throughput strategies that simultaneously explore multiple phenotypes from clinical trials’ datasets for genetic associations.

Blood Pressure Genetic Risk Score Predicts Blood Pressure Responses to Dietary Sodium and Potassium: The GenSalt Study (Genetic Epidemiology Network of Salt Sensitivity)

We examined the association between genetic risk score (GRS) for blood pressure (BP), based on single nucleotide polymorphisms identified in previous BP genome-wide association study meta-analyses, and salt and potassium sensitivity of BP among participants of the GenSalt study (Genetic Epidemiology Network of Salt Sensitivity). The GenSalt study was conducted among 1906 participants who underwent a 7-day low-sodium (51.3 mmol sodium/d), 7-day high-sodium (307.8 mmol sodium/d), and 7-day high-sodium plus potassium (60 mmol potassium/d) intervention. BP was measured 9× at baseline and at the end of each intervention period using a random zero sphygmomanometer. Associations between systolic BP (SBP), diastolic BP, and mean arterial pressure GRS and respective SBP, diastolic BP, and mean arterial pressure responses to the dietary interventions were assessed using mixed linear regression models that accounted for familial dependencies and adjusted for age, sex, field center, body mass index, and baseline BP. As expected, baseline SBP, diastolic BP, and mean arterial pressure significantly increased per quartile increase in GRS (P=2.7×10^-8, 9.8×10^-8, and 6.4×10^-6, respectively). In contrast, increasing GRS quartile conferred smaller SBP, diastolic BP, and mean arterial pressure responses to the low-sodium intervention (P=1.4×10^-3, 0.02, and 0.06, respectively) and smaller SBP responses to the high-sodium and potassium interventions (P=0.10 and 0.05). In addition, overall findings were similar when examining GRS as a continuous measure. Contrary to our initial hypothesis, we identified an inverse relationship between BP GRS and salt and potassium sensitivity of BP. These data may provide novel implications on the relationship between BP responses to dietary sodium and potassium and hypertension.

Human Missense Mutations in Regulator of G Protein Signaling 2 Affect the Protein Function Through Multiple Mechanisms

Regulator of G protein signaling 2 (RGS2) plays a significant role in alleviating vascular contraction and promoting vascular relaxation due to its GTPase accelerating protein activity toward Gαq. Mice lacking RGS2 display a hypertensive phenotype, and several RGS2 missense mutations have been found predominantly in hypertensive human subjects. However, the mechanisms whereby these mutations could impact blood pressure is unknown. Here, we selected 16 rare, missense mutations in RGS2 identified in various human exome sequencing projects and evaluated their ability to inhibit intracellular calcium release mediated by angiotensin II receptor type 1 (AT1R). Four of them had reduced function and were further investigated to elucidate underlying mechanisms. Low protein expression, protein mislocalization, and reduced G protein binding were identified as likely mechanisms of the malfunctioning mutants. The Q2L mutant had 50% lower RGS2 than wild-type (WT) protein detected by Western blot. Confocal microscopy demonstrated that R44H and D40Y had impaired plasma membrane targeting; only 46% and 35% of those proteins translocated to the plasma membrane when coexpressed with Gαq Q209L compared with 67% for WT RGS2. The R188H mutant had a significant reduction in Gαq binding affinity (10-fold increase in Ki compared with WT RGS2 in a flow cytometry competition binding assay). This study provides functional data for 16 human RGS2 missense variants on their effects on AT1R-mediated calcium mobilization and provides molecular understanding of those variants with functional loss in vitro. These molecular behaviors can provide insight to inform antihypertensive therapeutics in individuals with variants having reduced function.

Towards Precision Medicine for Hypertension: A Review of Genomic, Epigenomic, and Microbiomic Effects on Blood Pressure in Experimental Rat Models and Humans

Compelling evidence for the inherited nature of essential hypertension has led to extensive research in rats and humans. Rats have served as the primary model for research on the genetics of hypertension resulting in identification of genomic regions that are causally associated with hypertension. In more recent times, genome-wide studies in humans have also begun to improve our understanding of the inheritance of polygenic forms of hypertension. Based on the chronological progression of research into the genetics of hypertension as the "structural backbone," this review catalogs and discusses the rat and human genetic elements mapped and implicated in blood pressure regulation. Furthermore, the knowledge gained from these genetic studies that provide evidence to suggest that much of the genetic influence on hypertension residing within noncoding elements of our DNA and operating through pervasive epistasis or gene-gene interactions is highlighted. Lastly, perspectives on current thinking that the more complex "triad" of the genome, epigenome, and the microbiome operating to influence the inheritance of hypertension, is documented. Overall, the collective knowledge gained from rats and humans is disappointing in the sense that major hypertension-causing genes as targets for clinical management of essential hypertension may not be a clinical reality. On the other hand, the realization that the polygenic nature of hypertension prevents any single locus from being a relevant clinical target for all humans directs future studies on the genetics of hypertension towards an individualized genomic approach.

The genomic landscape of African populations in health and disease

A deeper appreciation of the complex architecture of African genomes is critical to the global effort to understand human history, biology and differential distribution of disease by geography and ancestry. Here, we report on how the growing engagement of African populations in genome science is providing new insights into the forces that shaped human genomes before and after the Out-of-Africa migrations. As a result of this human evolutionary history, African ancestry populations have the greatest genomic diversity in the world, and this diversity has important ramifications for genomic research. In the case of pharmacogenomics, for instance, variants of consequence are not limited to those identified in other populations, and diversity within African ancestry populations precludes summarizing risk across different African ethnic groups. Exposure of Africans to fatal pathogens, such as Plasmodium falciparum, Lassa Virus and Trypanosoma brucei rhodesiense, has resulted in elevated frequencies of alleles conferring survival advantages for infectious diseases, but that are maladaptive in modern-day environments. Illustrating with cardiometabolic traits, we show that while genomic research in African ancestry populations is still in early stages, there are already many examples of novel and African ancestry-specific disease loci that have been discovered. Furthermore, the shorter haplotypes in African genomes have facilitated fine-mapping of loci discovered in other human ancestry populations. Given the insights already gained from the interrogation of African genomes, it is imperative to continue and increase our efforts to describe genomic risk in and across African ancestry populations.

Shared genetic risk between migraine and coronary artery disease: A genome-wide analysis of common variants

Migraine is a recurrent pain condition traditionally viewed as a neurovascular disorder, but little is known of its vascular basis. In epidemiological studies migraine is associated with an increased risk of cardiovascular disease, including coronary artery disease (CAD), suggesting shared pathogenic mechanisms. This study aimed to determine the genetic overlap between migraine and CAD, and to identify shared genetic risk loci, utilizing a conditional false discovery rate approach and data from two large-scale genome-wide association studies (GWAS) of CAD (C4D, 15,420 cases, 15,062 controls; CARDIoGRAM, 22,233 cases, 64,762 controls) and one of migraine (22,120 cases, 91,284 controls). We found significant enrichment of genetic variants associated with CAD as a function of their association with migraine, which was replicated across two independent CAD GWAS studies. One shared risk locus in the PHACTR1 gene (conjunctional false discovery rate for index SNP rs9349379 < 3.90 x 10⁻⁵), which was also identified in previous studies, explained much of the enrichment. Two further loci (in KCNK5 and AS3MT) showed evidence for shared risk (conjunctional false discovery rate < 0.05). The index SNPs at two of the three loci had opposite effect directions in migraine and CAD. Our results confirm previous reports that migraine and CAD share genetic risk loci in excess of what would be expected by chance, and highlight one shared risk locus in PHACTR1. Understanding the biological mechanisms underpinning this shared risk is likely to improve our understanding of both disorders.

The antihypertensive MTHFR gene polymorphism rs17367504-G is a possible novel protective locus for preeclampsia

OBJECTIVE

Preeclampsia is a complex heterogeneous disease commonly defined by new-onset hypertension and proteinuria in pregnancy. Women experiencing preeclampsia have increased risk for cardiovascular diseases (CVD) later in life. Preeclampsia and CVD share risk factors and pathophysiologic mechanisms, including dysregulated inflammation and raised blood pressure. Despite commonalities, little is known about the contribution of shared genes (pleiotropy) to these diseases. This study aimed to investigate whether genetic risk factors for hypertension or inflammation are pleiotropic by also being associated with preeclampsia.

METHODS

We genotyped 122 single nucleotide polymorphisms (SNPs) in women with preeclampsia (n = 1006) and nonpreeclamptic controls (n = 816) from the Norwegian HUNT Study. SNPs were chosen on the basis of previously reported associations with either nongestational hypertension or inflammation in genome-wide association studies. The SNPs were tested for association with preeclampsia in a multiple logistic regression model.

RESULTS

The minor (G) allele of the intronic SNP rs17367504 in the gene methylenetetrahydrofolate reductase (MTHFR) was associated with a protective effect on preeclampsia (odds ratio 0.65, 95% confidence interval 0.53-0.80) in the Norwegian cohort. This association did not replicate in an Australian preeclampsia case-control cohort (P = 0.68, odds ratio 1.05, 95% confidence interval 0.83-1.32, minor allele frequency = 0.15).

CONCLUSION

MTHFR is important for regulating transmethylation processes and is involved in regulation of folate metabolism. The G allele of rs17367504 has previously been shown to protect against nongestational hypertension. Our study suggests a novel association between this allele and reduced risk for preeclampsia. This is the first study associating the minor (G) allele of a SNP within the MTHFR gene with a protective effect on preeclampsia, and in doing so identifying a possible pleiotropic protective effect on preeclampsia and hypertension.

Dissecting the genetic components of a quantitative trait locus for blood pressure and renal pathology on rat chromosome 3

BACKGROUND

We have previously confirmed the importance of rat chromosome 3 (RNO3) genetic loci on blood pressure elevation, pulse pressure (PP) variability and renal pathology during salt challenge in the stroke-prone spontaneously hypertensive (SHRSP) rat. The aims of this study were to generate a panel of RNO3 congenic sub-strains to genetically dissect the implicated loci and identify positional candidate genes by microarray expression profiling and analysis of next-generation sequencing data.

METHOD AND RESULTS

A panel of congenic sub-strains were generated containing Wistar-Kyoto (WKY)-introgressed segments of varying size on the SHRSP genetic background, focused within the first 50 Mbp of RNO3. Haemodynamic profiling during salt challenge demonstrated significantly reduced systolic blood pressure, diastolic blood pressure and PP variability in SP.WKYGla3a, SP.WKYGla3c, SP.WKYGla3d and SP.WKYGla3e sub-strains. Only SBP and DBP were significantly reduced during salt challenge in SP.WKYGla3b and SP.WKYGla3f sub-strains, whereas SP.WKYGla3g rats did not differ in haemodynamic response to SHRSP. Those sub-strains demonstrating significantly reduced PP variability during salt challenge also demonstrated significantly reduced renal pathology and proteinuria. Microarray expression profiling prioritized two candidate genes for blood pressure regulation (Dnm1, Tor1b), localized within the common congenic interval shared by SP.WKYGla3d and SP.WKYGla3f strains, and one candidate gene for salt-induced PP variability and renal pathology (Rabgap1), located within the region unique to the SP.WKYGla3d strain. Comparison of next-generation sequencing data identified variants within additional positional genes that are likely to affect protein function.

CONCLUSION

This study has identified distinct intervals on RNO3-containing genes that may be important for blood pressure regulation and renal pathology during salt challenge.

Genetics of hypertension: an assessment of progress in the spontaneously hypertensive rat

The application of gene mapping methods to uncover the genetic basis of hypertension in the inbred spontaneously hypertensive rat (SHR) began over 25 yr ago. This animal provides a useful model of genetic high blood pressure, and some of its features are described. In particular, it appears to be a polygenic model of disease, and polygenes participate in human hypertension genetic risk. The SHR hypertension alleles were fixed rapidly by selective breeding in just a few generations and so are presumably common genetic variants present in the outbred Wistar strain from which SHR was created. This review provides a background to the origins and genesis of this rat line. It considers its usefulness as a model organism for a common cardiovascular disease. The progress and obstacles facing mapping are considered in depth, as are the emergence and application of other genome-wide genetic discovery approaches that have been applied to investigate this model. Candidate genes, their identification, and the evidence to support their potential role in blood pressure elevation are considered. The review assesses the progress that has arisen from this work has been limited. Consideration is given to some of the factors that have impeded progress, and prospects for advancing understanding of the genetic basis of hypertension in this model are discussed.

A new risk locus in CHCHD5 for hypertension and obesity in a Chinese child population: a cohort study

OBJECTIVE

Coiled-coil-helix-coiled-coil-helix domain containing 5 (CHCHD5), a mitochondrial protein, is involved in the oxidative folding process in the mitochondrial intermembrane space. A previous study identified a hypertension-related single nucleotide polymorphism (SNP), rs3748024, in CHCHD5 in adults, but there are no reports regarding the association between CHCHD5 and obesity, which is a known risk factor for hypertension. The aim of the present study is to investigate the associations of the SNP rs3748024 with hypertension and obesity.

DESIGN

Cohort study.

SETTING

Institute of Pediatrics in China.

PARTICIPANTS

We genotyped the SNP rs3748024 in the Beijing Child and Adolescent Metabolic Syndrome study. A total of 3503 children participated in the study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Genotyping of rs3748024 was conducted using the TaqMan Allelic Discrimination Assay. Lipids and glucose were analysed by an automatic biochemical analyser using a kit assay. The levels of adipocytokines (leptin, adiponectin and resistin) were measured by ELISA techniques.

RESULTS

There was a statistically significant association between rs3748024 and systolic blood pressure (SBP) (β=-0.853, 95% CI -1.482 to -0.024, p=0.044) under an additive model adjusted for age, gender and body mass index (BMI) after correction for multiple testing. The SNP was also significantly associated with BMI (β=-0.286, 95% CI -0.551 to -0.021, p=0.043), obesity (OR=0.828, 95% CI 0.723 to 0.949, p=0.018) and triglycerides (β=-0.039, 95% CI -0.070 to -0.007, p=0.044) after correction for multiple testing.

CONCLUSIONS

We demonstrate for the first time that the SNP rs3748024 in CHCHD5 is associated with SBP, BMI, obesity and triglycerides in Chinese children. Our study identifies a new risk locus for hypertension and obesity in a child population. The function of CHCHD5 remains to be further studied to help elucidate the pathogenic role of CHCHD5 in hypertension and obesity.

Genetic mechanisms of human hypertension and their implications for blood pressure physiology

Hypertension, or elevated blood pressure, constitutes a major public health burden that affects more than 1 billion people worldwide and contributes to ~9 million deaths annually. Hereditary factors are thought to contribute to up to 50% of interindividual blood pressure variability. Blood pressure in the general population approximately shows a normal distribution and is thought to be a polygenic trait. In rare cases, early-onset hypertension or hypotension are inherited as Mendelian traits. The identification of the underlying Mendelian genes and variants has contributed to our understanding of the physiology of blood pressure regulation, emphasizing renal salt handling and the renin angiotensin aldosterone system as players in the determination of blood pressure. Genome-wide association studies (GWAS) have revealed more than 100 variants that are associated with blood pressure, typically with small effect sizes, which cumulatively explain ~3.5% of blood pressure trait variability. Several GWAS associations point to a role of the vasculature in the pathogenesis of hypertension. Despite these advances, the majority of the genetic contributors to blood pressure regulation are currently unknown; whether large-scale exome or genome sequencing studies will unravel these factors remains to be determined.

ATP2B1 gene Silencing Increases Insulin Sensitivity through Facilitating Akt Activation via the Ca2+/calmodulin Signaling Pathway and Ca2+-associated eNOS Activation in Endothelial Cells

Endothelial cell insulin resistance may be partially responsible for the higher risk of atherosclerosis and cardiovascular disease in populations with insulin resistance and type 2 diabetes mellitus (T2DM). A genome-wide association study revealed a significant association between the ATPase plasma membrane Ca²⁺ transporting 1 (ATP2B1) gene and T2DM in two community-based cohorts from the Korea Association Resource Project. However, little is known about the implication of the ATP2B1 gene on T2DM. In the present study, we investigated the role of the ATP2B1 gene in endothelial cell insulin sensitivity. ATP2B1 gene silencing resulted in enhanced intracellular calcium concentrations and increased insulin-induced Akt activation compared to that in the negative siRNA-transfected HUVECs (Human Umbilical Vein Endothelial Cells). The elevated insulin sensitivity mediated by ATP2B1 gene silencing was Ca²⁺/calmodulin-dependent, as verified by administration of the calcium chelator BAPTA-AM or the calmodulin-specific antagonist W7. Moreover, higher levels of phosphorylation of eNOS (Ser1177) were observed in ATP2B1-silenced HUVECs. In addition to BAPTA-AM and W7, L-NAME, an eNOS antagonist, abolished insulin-induced Akt phosphorylation at Ser473 in both si-Neg and si-ATP2B1-transfected endothelial cells. These results indicate that the enhanced insulin sensitivity in ATP2B1-silenced endothelial cells is alternatively dependent on an increase in intracellular Ca²⁺ and the subsequent activation of the Ca²⁺/calmodulin/eNOS/Akt signaling pathway. In summary, ATP2B1 gene silencing increased insulin sensitivity in endothelial cells by directly modulating the Ca²⁺/calmodulin signaling pathway and via the Ca²⁺/calmodulin/eNOS/Akt signaling pathway alternatively.

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

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

Bevacizumab-induced hypertension: Clinical presentation and molecular understanding

Bevacizumab is a vascular endothelial growth factor-A-specific angiogenesis inhibitor indicated as an adjunct to chemotherapy for the treatment of several types of cancer. Hypertension is commonly observed during bevacizumab treatment, and high-grade toxicity can limit therapy and lead to other cardiovascular complications. The factors that contribute to interindividual variability in blood pressure response to bevacizumab treatment are not well understood. In this review, we outline research efforts to understand the mechanisms and pathophysiology of hypertension resulting from bevacizumab treatment. Moreover, we highlight current knowledge of the pharmacogenetics of bevacizumab-induced hypertension, which may be used to develop strategies to prevent or minimize this toxicity.

Novel Blood Pressure Locus and Gene Discovery Using Genome-Wide Association Study and Expression Data Sets From Blood and the Kidney

Elevated blood pressure is a major risk factor for cardiovascular disease and has a substantial genetic contribution. Genetic variation influencing blood pressure has the potential to identify new pharmacological targets for the treatment of hypertension. To discover additional novel blood pressure loci, we used 1000 Genomes Project-based imputation in 150 134 European ancestry individuals and sought significant evidence for independent replication in a further 228 245 individuals. We report 6 new signals of association in or near HSPB7, TNXB, LRP12, LOC283335, SEPT9, and AKT2, and provide new replication evidence for a further 2 signals in EBF2 and NFKBIA. Combining large whole-blood gene expression resources totaling 12 607 individuals, we investigated all novel and previously reported signals and identified 48 genes with evidence for involvement in blood pressure regulation that are significant in multiple resources. Three novel kidney-specific signals were also detected. These robustly implicated genes may provide new leads for therapeutic innovation.

Recent Updates on the Proximal Tubule Renin-Angiotensin System in Angiotensin II-Dependent Hypertension

It is well recognized that the renin-angiotensin system (RAS) exists not only as circulating, paracrine (cell to cell), but also intracrine (intracellular) system. In the kidney, however, it is difficult to dissect the respective contributions of circulating RAS versus intrarenal RAS to the physiological regulation of proximal tubular Na(+) reabsorption and hypertension. Here, we review recent studies to provide an update in this research field with a focus on the proximal tubular RAS in angiotensin II (ANG II)-induced hypertension. Careful analysis of available evidence supports the hypothesis that both local synthesis or formation and AT1 (AT1a) receptor- and/or megalin-mediated uptake of angiotensinogen (AGT), ANG I and ANG II contribute to high levels of ANG II in the proximal tubules of the kidney. Under physiological conditions, nearly all major components of the RAS including AGT, prorenin, renin, ANG I, and ANG II would be filtered by the glomerulus and taken up by the proximal tubules. In ANG II-dependent hypertension, the expression of AGT, prorenin, and (pro)renin receptors, and angiotensin-converting enzyme (ACE) is upregulated rather than downregulated in the kidney. Furthermore, hypertension damages the glomerular filtration barrier, which augments the filtration of circulating AGT, prorenin, renin, ANG I, and ANG II and their uptake in the proximal tubules. Together, increased local ANG II formation and augmented uptake of circulating ANG II in the proximal tubules, via activation of AT1 (AT1a) receptors and Na(+)/H(+) exchanger 3, may provide a powerful feedforward mechanism for promoting Na(+) retention and the development of ANG II-induced hypertension.

Epidemiology in Germany-general development and personal experience

Did you ever hear about epidemiology in Germany? Starting from an epidemiological desert the discipline has grown remarkably, especially during the last 10-15 years: research institutes have been established, research funding has improved, multiple curriculae in Epidemiology and Public Health are offered. This increase has been quite steep, and now the epidemiological infrastructure is much better. Several medium-sized and even big population cohorts are ongoing, and the number and quality of publications from German epidemiologists has reached a respectable level. My own career in epidemiology started in the field of environmental health. After German reunification I concentrated for many years on environmental problems in East Germany and observed the health benefits after improvement of the situation. Later, I concentrated on population-based cohorts in newborns (GINI/LISA) and adults (KORA, German National Cohort), and on biobanking. This Essay describes the development in Germany after worldwar 2, illustrated by examples of research results and build-up of epidemiological infractructures worth mentioning.

Methods to estimate underlying blood pressure: The Atherosclerosis Risk in Communities (ARIC) Study

Antihypertensive medications complicate studies of blood pressure (BP) natural history; BP if untreated (“underlying BP”) needs to be estimated. Our objectives were to compare validity of five missing data imputation methods to estimate underlying BP and longitudinal associations of underlying BP and age. We simulated BP treatment in untreated hypertensive participants from Atherosclerosis Risk in Communities (ARIC) in visits 1–5 (1987–2013) using matched treated hypertensive participants. The underlying BP was imputed: #1, set as missing; #2, add 10 mmHg for systolic, 5 mmHg for diastolic; #3, add medication class-specific constant; #4, truncated normal regression; and #5, truncated normal regression including prior visit data. Longitudinal associations were estimated using linear mixed models of imputed underlying BP for simulated treated and measured BP for untreated participants. Method 3 was the best-performing for systolic BP; lowest relative bias (5.3% for intercept at age 50, 0% for age coefficient) and average deviation from expected (0.04 to -1.79). Method 2 performed best for diastolic BP; lowest relative bias (0.6% intercept at age 50, 33.3% age <60, 9.1% age 60+) and average deviation (-1.25 to -1.68). Methods 4 and 5 were comparable or slightly inferior. In conclusion, constant addition methods yielded valid and precise underlying BP and longitudinal associations.

Replication of a genome-wide association study on essential hypertension in Mongolians

Replication of genome-wide significant association SNPs in independent populations is an essential approach for identifying gene-disease relationships. Therefore, we sought to investigate the top 21 SNPs (rs10507454, rs11897156, rs11897991, rs12325203, rs12541835, rs13395322, rs1525035, rs16936892, rs17010027, rs17045859, rs17136827, rs1866525, rs2045590, rs4547758, rs4655688, rs7107438, rs761353, rs8127139, rs9312305, rs9407874 and rs9865108) from a genome-wide association study of essential hypertension in Mongolians. This was a community-based case-control study involving 428 hypertensives and 638 normotensives from Kerqinzuoyihou Banner,Tongliao, Inner Mongolian Autonomous Region, China. Genotyping was conducted with Sequenom MassArray (®) SNP detection technology. Overall, there were no significant differences in the genotype distributions and allele frequencies between the cases and controls. There was a significant difference between the allele frequencies at locus rs17010027 in cases (high systolic blood pressure) and controls in female (p = .036). There were significant differences in the distribution of genotypes and the allele frequencies at locus rs10507454 between cases (high diastolic blood pressure) and controls (p = .019 and p = .022, respectively) especially in male (p = .009 and p = .011, respectively). rs17010027 is associated with high systolic blood pressure in female, and rs10507454 is associated with high diastolic blood pressure especially in male of this Mongolian population.

Rare coding variants associated with blood pressure variation in 15 914 individuals of African ancestry

OBJECTIVES

Hypertension is a major risk factor for all cardiovascular diseases, especially among African Americans. This study focuses on identifying specific blood pressure (BP) genes using 15 914 individuals of African ancestry from eight cohorts (Africa America Diabetes Mellitus, Atherosclerosis Risk in Communities Study, Coronary Artery Risk Development in young Adults, Genetics Network, Genetic Epidemiology Network of Arteriopathy, Howard University Family Study, Hypertension Genetic Epidemiology Network, and Loyola University Chicago Cohort) to further genetic findings in this population which has generally been underrepresented in BP studies.

METHODS

We genotyped and performed various single variant and gene-based exome-wide analyses on 15 914 individuals on the Illumina HumanExome Beadchip v1.0 or v1.1 to test association with SBP and DBP long-term average residuals that were adjusted for age, age-squared, sex, and BMI.

RESULTS

We identified rare variants affecting SBP and DBP in 10 genes: AFF1, GAPDHS, SLC28A3, COL6A1, CRYBA2, KRBA1, SEL1L3, YOD1, CCDC13, and QSOX1. Prior experimental evidence for six of these 10 candidate genes supports their involvement in cardiovascular mechanisms, corroborating their potential roles in BP regulation.

CONCLUSION

Although our results require replication or validation due to their low numbers of carriers, and an ethnicity-specific genotyping array may be more informative, this study, which has identified several candidate genes in this population most susceptible to hypertension, presents one of the largest African-ancestry BP studies to date and the largest including analysis of rare variants.

Genomic Approaches to Hypertension

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

The ALDH2 gene rs671 polymorphism is not associated with essential hypertension

Essential hypertension (EH) is a worldwide problem. Acetaldehyde dehydrogenase 2 (ALDH2) gene has been suggested to be correlated with EH. However, the results are inconsistent. This study aimed to investigate the associations of ALDH2 rs671 polymorphism with EH in a Chinese Han population in Shanghai. Genotype of ALDH2 rs671 was analyzed in 1923 EH patients and 1115 control subjects. We found no association between ALDH2 rs671 and EH risk or EH-related quantitative blood chemistry values. Furthermore, a meta-analysis was performed and the summary results from 11220 patients and 8339 control subjects were consistent with our findings. These results indicated that rs671 of ALDH2 may not associate with the risk of EH.

[Genetic testing in polygenic diseases : Atrial fibrillation, arterial hypertension and coronary artery disease]

Genetic testing plays an increasing role in cardiovascular medicine. Advances in technology and the development of novel and more affordable (high throughput) methods have led to the identification of genetic risk factors in research and clinical practice. Also, this progress has simplified the screening of patients and individuals at risk. In case of rare monogenic diseases, diagnostics, risk stratification, and, in some cases, treatment decisions have become easier. For common, polygenic cardiovascular diseases, the situation is more complex due to interaction of modifiable external risk factors and nonmodifiable factors like genetic predisposition. Over the last few years, it has been shown that multiple genes are involved in the pathophysiology of these cardiovascular diseases rather than one single gene. In the following article, we give an overview of the genetic risk factors in polygenic cardiovascular diseases as atrial fibrillation, arterial hypertension and coronary artery disease. Furthermore, we aim to illustrate in which cases genetic testing is recommended in these diseases.

Association of CYP17A1 Genetic Polymorphisms and Susceptibility to Essential Hypertension in the Southwest Han Chinese Population

Background

The CYP17A1 gene encodes for cytochrome P450 enzyme CYP17A1, which is involved with the steroidogenic pathway including mineralocorticoids. The CYP17A1 polymorphisms might affect enzyme activity, then leading to a state of mineralocorticoid 11-deoxycorticosterone excess characterized by hypertension, suppressed plasma renin activity, and low aldosterone concentrations. The aim of this study was to investigate the contribution of CYP17A1 polymorphisms in inducing the susceptibility to essential hypertension among the Southwest Han Chinese population.

Material/Methods

Eight single nucleotide polymorphisms of CYP17A1 were genotyped in a case-control study for samples by polymerase chain reaction-restriction fragment length polymorphism analysis.

Results

The polymorphisms rs11191548 and rs4919687 were significantly associated with hypertension risk, which was confirmed by systolic and diastolic blood pressure distribution analyses between different genotype groups, and these two polymorphisms were found in linkage disequilibrium. The rs4919687 polymorphism was estimated to cause the destruction of exonic splicing silencer (ESR and Motif 3) sites and to transform the transcription factor AREB6 binding site, respectively, in the bioinformatics analyses. The haplotypes rs4919686A-rs3740397G -rs4919687C-rs743572C-rs11191548C and rs4919686A-rs3740397G-rs4919687T-rs743572C- rs11191548T were found to be susceptible to essential hypertension.

Conclusions

Our findings suggest that the CYP17A1 polymorphisms could be a genetic risk factor for essential hypertension among the Yunnan Han Chinese population, which would have implications for the treatment of this complex disorder.

SerpinC1/Antithrombin III in kidney-related diseases

The gene SerpinC1 encodes a serine protease inhibitor named antithrombin III (ATIII). This protease demonstrates both anticoagulant and anti-inflammatory action. ATIII is the most important coagulation factor inhibitor, and even minor changes in ATIII can significantly alter the risk of thromboembolism. ATIII can also suppress inflammation via a coagulation-dependent or -independent effect. Moreover, apart from ATIII deficiency, ATIII and its gene SerpinC1 may also be related to many diseases (e.g. hypertension, kidney diseases). The present review summarizes how ATIII affects the progress of kidney disease and its mechanism. Further studies are required to investigate how ATIII affects renal function and the treatment.