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Armstrong ND, Srinivasasainagendra V, Chekka LMS, Nguyen NHK, Nahid NA, Jones AC, Tanner RM, Hidalgo BA, Limdi NA, Claas SA, Gong Y, McDonough CW, Cooper-DeHoff RM, Johnson JA, Tiwari HK, Arnett DK, Irvin MR. Genetic Contributors of Efficacy and Adverse Metabolic Effects of Chlorthalidone in African Americans from the Genetics of Hypertension Associated Treatments (GenHAT) Study. Genes (Basel) 2022; 13:1260. [PMID: 35886043 PMCID: PMC9319619 DOI: 10.3390/genes13071260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/01/2022] [Accepted: 07/07/2022] [Indexed: 02/05/2023] Open
Abstract
Hypertension is a leading risk factor for cardiovascular disease mortality. African Americans (AAs) have the highest prevalence of hypertension in the United States, and to alleviate the burden of hypertension in this population, better control of blood pressure (BP) is needed. Previous studies have shown considerable interpersonal differences in BP response to antihypertensive treatment, suggesting a genetic component. Utilizing data from 4297 AA participants randomized to chlorthalidone from the Genetics of Hypertension Associated Treatments (GenHAT) study, we aimed to identify variants associated with the efficacy of chlorthalidone. An additional aim was to find variants that contributed to changes in fasting glucose (FG) in these individuals. We performed genome-wide association analyses on the change of systolic and diastolic BP (SBP and DBP) over six months and FG levels over 24 months of treatment. We sought replication in the International Consortia of Pharmacogenomics Studies. We identified eight variants statistically associated with BP response and nine variants associated with FG response. One suggestive LINC02211-CDH9 intergenic variant was marginally replicated with the same direction of effect. Given the impact of hypertension in AAs, this study implies that understanding the genetic background for BP control and glucose changes during chlorthalidone treatment may help prevent adverse cardiovascular events in this population.
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Affiliation(s)
- Nicole D. Armstrong
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (N.D.A.); (A.C.J.); (R.M.T.); (B.A.H.)
| | - Vinodh Srinivasasainagendra
- Department of Biostatistics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (V.S.); (H.K.T.)
| | - Lakshmi Manasa S. Chekka
- Division of Applied Regulatory Sciences, Center for Drug Evaluation and Research, Silver Spring, MD 20903, USA;
| | - Nam H. K. Nguyen
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL 32611, USA; (N.H.K.N.); (N.A.N.); (Y.G.); (C.W.M.); (R.M.C.-D.); (J.A.J.)
| | - Noor A. Nahid
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL 32611, USA; (N.H.K.N.); (N.A.N.); (Y.G.); (C.W.M.); (R.M.C.-D.); (J.A.J.)
| | - Alana C. Jones
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (N.D.A.); (A.C.J.); (R.M.T.); (B.A.H.)
- Medical Scientist Training Program, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Rikki M. Tanner
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (N.D.A.); (A.C.J.); (R.M.T.); (B.A.H.)
| | - Bertha A. Hidalgo
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (N.D.A.); (A.C.J.); (R.M.T.); (B.A.H.)
| | - Nita A. Limdi
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
| | - Steven A. Claas
- Department of Epidemiology, College of Public Health, University of Kentucky, Lexington, KY 40506, USA; (S.A.C.); (D.K.A.)
| | - Yan Gong
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL 32611, USA; (N.H.K.N.); (N.A.N.); (Y.G.); (C.W.M.); (R.M.C.-D.); (J.A.J.)
| | - Caitrin W. McDonough
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL 32611, USA; (N.H.K.N.); (N.A.N.); (Y.G.); (C.W.M.); (R.M.C.-D.); (J.A.J.)
| | - Rhonda M. Cooper-DeHoff
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL 32611, USA; (N.H.K.N.); (N.A.N.); (Y.G.); (C.W.M.); (R.M.C.-D.); (J.A.J.)
- Division of Cardiovascular Medicine, Department of Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Julie A. Johnson
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL 32611, USA; (N.H.K.N.); (N.A.N.); (Y.G.); (C.W.M.); (R.M.C.-D.); (J.A.J.)
- Division of Cardiovascular Medicine, Department of Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Hemant K. Tiwari
- Department of Biostatistics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (V.S.); (H.K.T.)
| | - Donna K. Arnett
- Department of Epidemiology, College of Public Health, University of Kentucky, Lexington, KY 40506, USA; (S.A.C.); (D.K.A.)
- Deans Office, College of Public Health, University of Kentucky, Lexington, KY 40506, USA
| | - Marguerite R. Irvin
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (N.D.A.); (A.C.J.); (R.M.T.); (B.A.H.)
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Kumar R, Kohli S, Mishra A, Garg R, Alam P, Stobdan T, Nejatizadeh A, Gupta M, Tyagi S, Pasha MAQ. Interactions between the genes of vasodilatation pathways influence blood pressure and nitric oxide level in hypertension. Am J Hypertens 2015; 28:239-47. [PMID: 25159081 DOI: 10.1093/ajh/hpu130] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND This study investigates the contribution of genetic interactions between the β-2 adrenergic receptor (ADRB2) and nitric oxide synthase (NOS3) genes to the complex etiology of hypertension. METHODS Using single nucleotide polymorphism (SNP) markers, we studied potential interactions between ADRB2 and NOS3 variants and their correlation with clinical, biochemical, and expression levels in 546 individuals with hypertension and 884 age-, sex-, and ethnicity-matched unrelated control subjects. Generalized multifactor dimensionality reduction (GMDR) analysis identified the models for genotype interaction. RESULTS The best models to represent association of genotypes with augmented hypertension susceptibility were the 4- and 5-locus interacting GMDR models of ADRB2 and NOS3 compared with within-gene 6-locus ADRB2 and 2-locus NOS3 (odds ratio (OR) = 4.8, P = 0.04; OR = 5.6, P = 0.02, respectively). Stratification of 4- and 5-locus GMDR models on the basis of risk alleles (in increasing order) increased the ORs from 1.26 to 14.17 and from 0.81 to 14.18, respectively, and correlated linearly with increased systolic blood pressure, diastolic blood pressure, and mean arterial pressure and decreased nitric oxide level (P ≤ 0.0004). We performed various analyses, such as single-locus, genetic interactions, sliding-window, and comparative analysis. Each analysis consistently revealed the 46A allele of ADRB2 46G/A SNP and 4a allele of NOS3 4b/4a SNP to be associated with risk of hypertension. These risk-conferring markers were associated with decreased ADRB2 and NOS3 expression and decreased nitric oxide level in the patients (P ≤ 0.04). CONCLUSIONS Evidence of interaction between the genetic loci of ADRB2 and NOS3 points to varied clinical, biochemical, and expression levels and a role in hypertension susceptibility.
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Affiliation(s)
- Rahul Kumar
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India; Present address: Division of Pulmonary Sciences and Critical Care Medicine, School of Medicine, University of Colorado, Denver, Colorado (R.K.); Department of Pediatrics, Division of Respiratory Medicine, University of California San Diego, La Jolla, California (T.S.); Research Center for Molecular Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran (A.N.)
| | - Samantha Kohli
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India; Academy of Scientific and Innovative Research, New Delhi, India
| | - Aastha Mishra
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Ritu Garg
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Perwez Alam
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Tsering Stobdan
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India; Present address: Division of Pulmonary Sciences and Critical Care Medicine, School of Medicine, University of Colorado, Denver, Colorado (R.K.); Department of Pediatrics, Division of Respiratory Medicine, University of California San Diego, La Jolla, California (T.S.); Research Center for Molecular Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran (A.N.)
| | - Azim Nejatizadeh
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India; Present address: Division of Pulmonary Sciences and Critical Care Medicine, School of Medicine, University of Colorado, Denver, Colorado (R.K.); Department of Pediatrics, Division of Respiratory Medicine, University of California San Diego, La Jolla, California (T.S.); Research Center for Molecular Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran (A.N.)
| | - Mohit Gupta
- Department of Cardiology, Govind Ballabh Pant Hospital, New Delhi, India
| | - Sanjay Tyagi
- Department of Cardiology, Govind Ballabh Pant Hospital, New Delhi, India
| | - M A Qadar Pasha
- Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, India; Academy of Scientific and Innovative Research, New Delhi, India;
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Korbolina EE, Ershov NI, Bryzgalov LO, Kolosova NG. Application of quantitative trait locus mapping and transcriptomics to studies of the senescence-accelerated phenotype in rats. BMC Genomics 2014; 15 Suppl 12:S3. [PMID: 25563673 PMCID: PMC4303943 DOI: 10.1186/1471-2164-15-s12-s3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background Etiology of complex disorders, such as cataract and neurodegenerative diseases including age-related macular degeneration (AMD), remains poorly understood due to the paucity of animal models, fully replicating the human disease. Previously, two quantitative trait loci (QTLs) associated with early cataract, AMD-like retinopathy, and some behavioral aberrations in senescence-accelerated OXYS rats were uncovered on chromosome 1 in a cross between OXYS and WAG rats. To confirm the findings, we generated interval-specific congenic strains, WAG/OXYS-1.1 and WAG/OXYS-1.2, carrying OXYS-derived loci of chromosome 1 in the WAG strain. Both congenic strains displayed early cataract and retinopathy but differed clinically from OXYS rats. Here we applied a high-throughput RNA sequencing (RNA-Seq) strategy to facilitate nomination of the candidate genes and functional pathways that may be responsible for these differences and can contribute to the development of the senescence-accelerated phenotype of OXYS rats. Results First, the size and map position of QTL-derived congenic segments were determined by comparative analysis of coding single-nucleotide polymorphisms (SNPs), which were identified for OXYS, WAG, and congenic retinal RNAs after sequencing. The transferred locus was not what we expected in WAG/OXYS-1.1 rats. In rat retina, 15442 genes were expressed. Coherent sets of differentially expressed genes were identified when we compared RNA-Seq retinal profiles of 20-day-old WAG/OXYS-1.1, WAG/OXYS-1.2, and OXYS rats. The genes most different in the average expression level between the congenic strains included those generally associated with the Wnt, integrin, and TGF-β signaling pathways, widely involved in neurodegenerative processes. Several candidate genes (including Arhgap33, Cebpg, Gtf3c1, Snurf, Tnfaip3, Yme1l1, Cbs, Car9 and Fn1) were found to be either polymorphic in the congenic loci or differentially expressed between the strains. These genes may contribute to the development of cataract and retinopathy. Conclusions This study is the first RNA-Seq analysis of the rat retinal transcriptome generated with 40 mln sequencing read depth. The integration of QTL and transcriptomic analyses in our study forms the basis of future research into the relationship between the candidate genes within the congenic regions and specific changes in the retinal transcriptome as possible causal mechanisms that underlie age-associated disorders.
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Abstract
Hypertension has become a major global health burden due to its high prevalence and associated increase in risk of cardiovascular disease and premature death. It is well established that hypertension is determined by both genetic and environmental factors and their complex interactions. Recent large-scale meta-analyses of genome-wide association studies (GWAS) have successfully identified a total of 38 loci which achieved genome-wide significance (P < 5 × 10(-8)) for their association with blood pressure (BP). Although the heritability of BP explained by these loci is very limited, GWAS meta-analyses have elicited renewed optimism in hypertension genomics research, highlighting novel pathways influencing BP and elucidating genetic mechanisms underlying BP regulation. This review summarizes evolving progress in the rapidly moving field of hypertension genetics and highlights several promising approaches for dissecting the remaining heritability of BP. It also discusses the future translation of genetic findings to hypertension treatment and prevention.
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Simino J, Shi G, Weder A, Boerwinkle E, Hunt SC, Rao DC. Body mass index modulates blood pressure heritability: the Family Blood Pressure Program. Am J Hypertens 2014; 27:610-9. [PMID: 24029162 PMCID: PMC3958601 DOI: 10.1093/ajh/hpt144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 07/22/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Candidate gene and twin studies suggest that interactions between body mass index (BMI) and genes contribute to the variability of blood pressure (BP). To determine whether there is evidence for gene-BMI interactions, we investigated the modulation of BP heritability by BMI using 4,153 blacks, 1,538 Asians, 4,013 whites, and 2,199 Hispanic Americans from the Family Blood Pressure Program. METHODS To capture the BP heritability dependence on BMI, we employed a generalized variance components model incorporating linear and Gaussian interactions between BMI and the genetic component. Within each race and network subgroup, we used the Akaike information criterion and likelihood ratio test to select the appropriate interaction function for each BP trait (systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP)) and determine interaction significance, respectively. RESULTS BP heritabilities were significantly modified by BMI in the GenNet and SAPPHIRe Networks, which contained the youngest and least-obese participants, respectively. GenNet Whites had unimodal SBP, MAP, and PP heritabilities that peaked between BMI values of 33 and 37kg/m(2). The SBP and MAP heritabilities in GenNet Hispanic Americans, as well as the PP heritability in GenNet blacks, were increasing functions of BMI. The DBP and SBP heritabilities in the SAPPHIRe Chinese and Japanese, respectively, were decreasing functions of BMI. CONCLUSIONS BP heritability differed by BMI in the youngest and least-obese networks, although the shape of this dependence differed by race. Use of nonlinear gene-BMI interactions may enhance BP gene discovery efforts in individuals of European ancestry.
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Affiliation(s)
- Jeannette Simino
- Division of Biostatistics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri
| | - Gang Shi
- Division of Biostatistics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri
| | - Alan Weder
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan
| | - Eric Boerwinkle
- Human Genetics Center, University of Texas Health Sciences Center, Houston, Texas
| | - Steven C. Hunt
- Cardiovascular Genetics Division, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Dabeeru C. Rao
- Division of Biostatistics, Washington University in St. Louis, School of Medicine, St. Louis, Missouri
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Basson J, Sung YJ, Schwander K, Kume R, Simino J, de las Fuentes L, Rao D. Gene-education interactions identify novel blood pressure loci in the Framingham Heart Study. Am J Hypertens 2014; 27:431-44. [PMID: 24473254 DOI: 10.1093/ajh/hpt283] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Blood pressure (BP) variability has a genetic component, most of which has yet to be attributed to specific variants. One promising strategy for gene discovery is analysis of interactions between single-nucleotide polymorphisms (SNPs) and BP-related factors, including age, sex, and body mass index (BMI). Educational attainment, a marker for socioeconomic status, has effects on both BP and BMI. METHODS We investigated SNP-education interaction effects on BP in genome-wide data on 3,836 subjects in families from the Framingham Heart Study. The ABEL suite was used to adjust for age, sex, BMI, medication use, and kinship and to perform 1 degree-of-freedrom (df) and 2 df SNP-education interaction tests. RESULTS An SNP in PTN was associated with increased systolic BP (5.4mm Hg per minor allele) in those without a bachelor's degree but decreased systolic BP (1.6mm Hg per allele) in those with a bachelor's degree (2 df; P = 2.08 × 10(-8)). An SNP in TOX2 was associated with increased diastolic BP (DBP; 4.1mm Hg per minor allele) in those with no more educational attainment than high school but decreased DBP in those with education past high school (-0.7; 1 df; P = 3.74 × 10(-8)). Three suggestive associations were also found: in MYO16 (pulse pressure: 2 df; P = 2.89 × 10(-7)), in HAS2 (DBP: 1 df; P = 1.41 × 10(-7)), and in DLEU2 (DBP: 2 df; P = 1.93 × 10(-7)). All 5 genes are related to BP, including roles in vasodilation and angiogenesis for PTN and TOX2. CONCLUSIONS PTN and TOX2 are associated with BP. Analyzing SNP-education interactions may detect novel associations. Education may be a surrogate for unmeasured exposures and behaviors modifying SNP effects on BP.
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Affiliation(s)
- Jacob Basson
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri, USA
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P2X7 receptor polymorphisms do not influence endothelial function and vascular tone in neo-diagnosed, treatment-naive essential hypertensive patients. J Hypertens 2013; 31:2362-9. [DOI: 10.1097/hjh.0b013e3283653ff5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Abstract
PURPOSE OF REVIEW Modern molecular techniques are identifying pathways and genes involved in the pathogenesis of the complex disorder essential hypertension. This review provides an overview of genetic methodologies and recent results in the study of high blood pressure (BP), hypertension-attributed nephropathy, and related intermediate phenotypes. RECENT FINDINGS Candidate gene studies have implicated aberrations in ion channels, ion channel regulation, aldosterone signaling, vasoconstriction and inflammation in essential hypertension; genome-wide association studies (GWAS) have detected more than 50 BP loci, most previously unsuspected in essential hypertension. Mapping by admixture linkage disequilibrium (MALD; or admixture mapping) recently led to a major breakthrough in hypertension-attributed kidney disease in African Americans, demonstrating the role of the apolipoprotein L1 (APOL1) and nonmuscle myosin heavy chain 9 (MYH9) genes in this primary kidney disease residing in the spectrum of focal segmental glomerulosclerosis. GWAS have detected associations between kidney function and UMOD and SHROOM3. SUMMARY Genetic studies confirm that 'essential hypertension' consists of disparate mechanisms that ultimately lead to elevations in systemic BP. The cause of hypertension in the majority of cases remains unknown. It is anticipated that epigenetic phenomena, rare exonic mutations, and interactions with environmental factors make additional contributions.
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Searching for genes involved in hypertension development in special populations: children and pre-eclamptic women. Where are we standing now? Clin Chem Lab Med 2013; 51:2253-69. [DOI: 10.1515/cclm-2013-0405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/23/2013] [Indexed: 01/02/2023]
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A two-stage matched case-control study on multiple hypertensive candidate genes in Han Chinese. Am J Hypertens 2012; 25:804-11. [PMID: 22534794 DOI: 10.1038/ajh.2012.44] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Hypertension affects about 1/3 of adults worldwide, ~3.8 million in Taiwan, 160 million in China, and 1 billion worldwide. It is a major risk factor leading to stroke, cardiovascular disease, and end-stage renal disease. In each year, more than 13.5 million deaths are due to hypertension-related diseases worldwide. METHODS We performed a two-stage association study of hypertension using genotype data of single-nucleotide polymorphisms (SNPs) from 992 young-onset hypertensive cases and 992 matched controls of Han Chinese in Taiwan. A total of 238 SNPs of 36 highly replicated hypertension candidate genes with functional importance were investigated. Association analysis was carried out using conditional logistic regression. RESULTS We identified two SNPs that were strongly associated with hypertension in both the first and the second stages. The first SNP (rs2301339) is located at guanine nucleotide-binding protein β3 subunit (GNB3) and the other one (rs17254521) is located at insulin receptor (INSR). CONCLUSIONS SNP rs2301339 is perfectly linked in linkage disequilibrium (LD) with C825T (rs5443) which has been associated with hypertension in Caucasian, but inconsistent in Asian populations. However, we found that in our sample this SNP has an opposite effect with the previous findings. In summary, this study identified one novel SNP in GNB3 and one novel SNP in INSR that are strongly associated with young-onset hypertension. Due to relatively small sample size, the results should still be interpreted with caution and need to be replicated in other studies.
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Hall JL, Duprez DA, Barac A, Rich SS. A review of genetics, arterial stiffness, and blood pressure in African Americans. J Cardiovasc Transl Res 2012; 5:302-8. [PMID: 22492025 PMCID: PMC3381797 DOI: 10.1007/s12265-012-9362-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 03/20/2012] [Indexed: 01/11/2023]
Abstract
The prevalence of hypertension in African Americans in the USA is among the highest in the world and increasing. The identification of genes and pathways regulating blood pressure in African Americans has been challenging. An early predictor of hypertension is arterial stiffness. The prevalence of arterial stiffness is significantly higher in African Americans compared to Caucasians. Approximately 20 % of the variance in arterial stiffness is estimated to be heritable. Identifying genes and biological pathways regulating arterial stiffness may provide insight into the genetics underlying the increased risk of hypertension in African Americans. This paper reviews the genetic findings to date in the area of arterial stiffness and blood pressure in African Americans with an emphasis on the current limitations and new efforts to move the field forward.
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Affiliation(s)
- Jennifer L Hall
- Division of Cardiology, Department of Medicine, Lillehei Heart Institute, University of Minnesota, 4-106 NHH, 312 Church Street, Minneapolis, MN 55455, USA.
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Between candidate genes and whole genomes: time for alternative approaches in blood pressure genetics. Curr Hypertens Rep 2012; 14:46-61. [PMID: 22161147 DOI: 10.1007/s11906-011-0241-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Blood pressure has a significant genetic component, but less than 3% of the observed variance has been attributed to genetic variants identified to date. Candidate gene studies of rare, monogenic hypertensive syndromes have conclusively implicated several genes altering renal sodium balance, and studies of essential hypertension have inconsistently implicated over 50 genes in pathways affecting renal sodium balance and other functions. Genome-wide linkage scans have replicated numerous quantitative trait loci throughout the genome, and over 50 single nucleotide polymorphisms (SNPs) have been replicated in multiple genome-wide association studies. These studies provide considerable evidence that epistasis and other interactions play a role in the genetic architecture of blood pressure regulation, but candidate gene studies have limited scope to test for epistasis, and genome-wide studies have low power for both main effects and interactions. This review summarizes the genetic findings to date for blood pressure, and it proposes focused, pathway-based approaches involving epistasis, gene-environment interactions, and next-generation sequencing to further the genetic dissection of blood pressure and hypertension.
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Simino J, Shi G, Arnett D, Broeckel U, Hunt SC, Rao DC. Variants on chromosome 6p22.3 associated with blood pressure in the HyperGEN study: follow-up of FBPP quantitative trait loci. Am J Hypertens 2011; 24:1227-33. [PMID: 21850057 PMCID: PMC3406604 DOI: 10.1038/ajh.2011.140] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND A recent meta-analysis of genome-wide linkage scans of blood pressure (BP) in the large (N = 13,044) Family Blood Pressure Program (FBPP) identified five quantitative trait loci (QTLs) on chromosomes 6, 8, 20, and 21. We conducted follow-up fine mapping studies in 1,251 African (AA) and 1,254 European American (EA) participants of the Hypertension Genetic Epidemiology Network (HyperGEN). METHODS Ethnic-specific linear mixed effects models were used to test associations of BP with genotyped and imputed single nucleotide polymorphisms (SNPs) contained in the logarithm of odds (LOD) score ≥2 interval under each of the QTL peaks. We used multipoint variance components models to perform linkage analysis conditional on each significant SNP in the QTL region to see if the SNP explained the QTL. RESULTS Three intergenic SNPs (rs898164, rs2876587, rs6935795) on chromosome 6p22.3 were significantly associated with pulse pressure (using appropriate Bonferroni correction). Conditioning on the significant SNPs reduced the chromosome 6 QTL linkage evidence by 14-30%. Both AAs and EAs exhibited suggestive associations between BP and intronic SNPs on chromosomes 8q24.12 (genes: OPG in AAs, SAMD12 in EAs), 20q13.12 (genes: SLC13A3 in AAs, SLC12A5 in EAs), and 21q21.1 (genes: C21orf34 in AAs, BC039377 in EAs). CONCLUSIONS Significant associations with common SNPs explained less than 1/3 of the QTL evidence. Our results cannot refute the hypothesis that rare variants account for most of the statistical evidence for the FBPP linkage peaks. Whole genome resequencing can identify the variants driving the linkage peaks and genome-wide association study (GWAS) hits thereby spurring investigations to deepen our understanding of hypertension pathophysiology.
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Affiliation(s)
- Jeannette Simino
- Division of Biostatistics, Washington University School of Medicine, Saint Louis, Missouri, USA
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Kumarasamy S, Gopalakrishnan K, Toland EJ, Yerga-Woolwine S, Farms P, Morgan EE, Joe B. Refined mapping of blood pressure quantitative trait loci using congenic strains developed from two genetically hypertensive rat models. Hypertens Res 2011; 34:1263-70. [PMID: 21814219 DOI: 10.1038/hr.2011.116] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Previously linkage and substitution mapping were conducted between the Dahl Salt-sensitive (S) rat and the Spontaneously Hypertensive Rat (SHR) to address the hypothesis that genetic contributions to blood pressure (BP) in two genetically hypertensive rat strains are different. Among the BP quantitative trait loci (QTLs) detected, two are located on chromosome 9 within large genomic segments. The goal of the current study was to develop new iterations of congenic substrains, to further resolve both of these BP QTLs on chromosome 9 as independent congenic segments. A total of 10 new congenic substrains were developed and characterized. The newly developed congenic substrains S.SHR(9)x8Ax11A and S.SHR(9)x10Ax1, with introgressed segments of 2.05 and 6.14 Mb, represented the shortest genomic segments. Both of these congenic substrains, S.SHR(9)x8Ax11A and S.SHR(9)x10Ax1 lowered BP of the S rat by 56 mm Hg (P<0.001) and 15 mm Hg (P<0.039), respectively. The BP measurements were corroborated by radiotelemetry. Urinary protein excretion was significantly lowered by SHR alleles within S.SHR(9)x10Ax1 but not by S.SHR(9)x8Ax11A. The shorter of the two congenic segments, 2.05 Mb was further characterized and found to contain a single differentially expressed protein-coding gene, Tomoregulin-2 (Tmeff2). The protein expression of Tmeff2 was higher in the S rat compared with S.SHR(9)x8Ax11A, which also had lower cardiac hypertrophy as measured by echocardiography. Tmeff2 is known to be upregulated in patients from multiple cohorts with cardiac hypertrophy. Taken together, Tmeff2 can be prioritized as a candidate gene for hypertension and associated cardiac hypertrophy in both rats and in humans.
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Affiliation(s)
- Sivarajan Kumarasamy
- Physiological Genomics Laboratory, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
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