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1.  The role of covariate heterogeneity in meta-analysis of gene-environment interactions with quantitative traits 
Genetic epidemiology  2014;38(5):416-429.
With challenges in data harmonization and covariate heterogeneity across various data sources, meta-analysis of gene-environment interaction studies can often involve subtle statistical issues. In this paper, we study the effect of environmental covariate heterogeneity (within and between cohorts) on two approaches for fixed-effect meta-analysis: the standard inverse-variance weighted meta-analysis and a meta-regression approach. Akin to the results in Simmonds and Higgins (2007), we obtain analytic efficiency results for both methods under the assumption of gene-environment independence. The relative efficiency of the two methods depends on the ratio of within- versus between- cohort variability of the environmental covariate. We propose to use an adaptively weighted estimator (AWE), between meta-analysis and meta-regression, for the interaction parameter. The AWE retains full efficiency of the joint analysis using individual level data under certain natural assumptions. Lin and Zeng (2010a, b) showed that a multivariate inverse-variance weighted estimator also had asymptotically full efficiency as joint analysis using individual level data, if the estimates with full covariance matrices for all the common parameters are pooled across all studies. We show consistency of our work with Lin and Zeng (2010a, b). Without sacrificing much efficiency, the AWE uses only univariate summary statistics from each study, and bypasses issues with sharing individual level data or full covariance matrices across studies. We compare the performance of the methods both analytically and numerically. The methods are illustrated through meta-analysis of interaction between Single Nucleotide Polymorphisms in FTO gene and body mass index on high-density lipoprotein cholesterol data from a set of eight studies of type 2 diabetes.
PMCID: PMC4108593  PMID: 24801060
2.  A genome-wide association study for venous thromboembolism: the extended Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium 
Genetic epidemiology  2013;37(5):512-521.
Venous thromboembolism (VTE) is a common, heritable disease resulting in high rates of hospitalization and mortality. Yet few associations between VTE and genetic variants, all in the coagulation pathway, have been established. To identify additional genetic determinants of VTE, we conducted a 2-stage genome-wide association study (GWAS) among individuals of European ancestry in the extended CHARGE VTE consortium. The discovery GWAS comprised 1,618 incident VTE cases out of 44,499 participants from six community-based studies. Genotypes for genome-wide single-nucleotide polymorphisms (SNPs) were imputed to ~2.5 million SNPs in HapMap and association with VTE assessed using study-design appropriate regression methods. Meta-analysis of these results identified two known loci, in F5 and ABO. Top 1,047 tag SNPs (p≤0.0016) from the discovery GWAS were tested for association in an additional 3,231 cases and 3,536 controls from three case-control studies. In the combined data from these two stages, additional genome-wide significant associations were observed on 4q35 at F11 (top SNP rs4253399, intronic to F11) and on 4q28 at FGG (rs6536024, 9.7 kb from FGG) (p<5.0×10−13 for both). The associations at the FGG locus were not completely explained by previously reported variants. Loci at or near SUSD1 and OTUD7A showed borderline yet novel associations (p<5.0×10-6) and constitute new candidate genes. In conclusion, this large GWAS replicated key genetic associations in F5 and ABO, and confirmed the importance of F11 and FGG loci for VTE. Future studies are warranted to better characterize the associations with F11 and FGG and to replicate the new candidate associations.
PMCID: PMC3990406  PMID: 23650146
venous thrombosis; genetics; genome-wide association; genetic epidemiology
3.  Orthostatic hypotension and novel blood pressure-associated gene variants: Genetics of Postural Hemodynamics (GPH) Consortium 
European Heart Journal  2012;33(18):2331-2341.
Orthostatic hypotension (OH), an independent predictor of mortality and cardiovascular events, strongly correlates with hypertension. Recent genome-wide studies have identified new loci influencing blood pressure (BP) in populations, but their impact on OH remains unknown.
Methods and results
A total of 38 970 men and women of European ancestry from five population-based cohorts were included, of whom 2656 (6.8%) met the diagnostic criteria for OH (systolic/diastolic BP drop ≥20/10 mmHg within 3 min of standing). Thirty-one recently discovered BP-associated single nucleotide polymorphisms (SNPs) were examined using an additive genetic model and the major allele as referent. Relations between OH, orthostatic systolic BP response, and genetic variants were assessed by inverse variance-weighted meta-analysis. We found Bonferroni adjusted (P < 0.0016) significant evidence for association between OH and the EBF1 locus (rs11953630, per-minor-allele odds ratio, 95% confidence interval: 0.90, 0.85–0.96; P = 0.001), and nominal evidence (P < 0.05) for CYP17A1 (rs11191548: 0.85, 0.75–0.95; P = 0.005), and NPR3-C5orf23 (rs1173771: 0.92, 0.87–0.98; P= 0.009) loci. Among subjects not taking BP-lowering drugs, three SNPs within the NPPA/NPPB locus were nominally associated with increased risk of OH (rs17367504: 1.13, 1.02–1.24; P = 0.02, rs198358: 1.10, 1.01–1.20; P = 0.04, and rs5068: 1.22, 1.04–1.43; P = 0.01). Moreover, an ADM variant was nominally associated with continuous orthostatic systolic BP response in the adjusted model (P= 0.04).
The overall association between common gene variants in BP loci and OH was generally weak and the direction of effect inconsistent with resting BP findings. These results suggest that OH and resting BP share few genetic components.
PMCID: PMC3442958  PMID: 22504314
Orthostatic hypotension; Genetics; Single nucleotide polymorphism; Steroid 17-alpha-hydroxylase; Natriuretic peptides; Adrenomedullin
4.  Common Variation in Fatty Acid Genes and Resuscitation from Sudden Cardiac Arrest 
Fatty acids provide energy and structural substrates for the heart and brain and may influence resuscitation from sudden cardiac arrest (SCA). We investigated whether genetic variation in fatty acid metabolism pathways was associated with SCA survival.
Methods and Results
Subjects (mean age 67, 80% male, Caucasian) were out-of-hospital SCA patients found in ventricular fibrillation in King County, WA. We compared subjects who survived to hospital admission (n=664) with those who did not (n=689), and subjects who survived to hospital discharge (n=334) with those who did not (n=1019). Associations between survival and genetic variants were assessed using logistic regression adjusting for age, gender, location, time to arrival of paramedics, whether the event was witnessed, and receipt of bystander CPR. Within-gene permutation tests were used to correct for multiple comparisons. Variants in five genes were significantly associated with SCA survival. After correction for multiple comparisons, SNPs in ACSL1 and ACSL3 were significantly associated with survival to hospital admission. SNPs in ACSL3, AGPAT3, MLYCD, and SLC27A6 were significantly associated with survival to hospital discharge.
Our findings indicate that variants in genes important in fatty acid metabolism are associated with SCA survival in this population.
PMCID: PMC3422654  PMID: 22661490
epidemiology; fatty acids; genetics; heart arrest
5.  Eight genetic loci associated with variation in lipoprotein-associated phospholipase A2 mass and activity and coronary heart disease: meta-analysis of genome-wide association studies from five community-based studies 
European Heart Journal  2011;33(2):238-251.
Lipoprotein-associated phospholipase A2 (Lp-PLA2) generates proinflammatory and proatherogenic compounds in the arterial vascular wall and is a potential therapeutic target in coronary heart disease (CHD). We searched for genetic loci related to Lp-PLA2 mass or activity by a genome-wide association study as part of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium.
Methods and results
In meta-analyses of findings from five population-based studies, comprising 13 664 subjects, variants at two loci (PLA2G7, CETP) were associated with Lp-PLA2 mass. The strongest signal was at rs1805017 in PLA2G7 [P = 2.4 × 10−23, log Lp-PLA2 difference per allele (beta): 0.043]. Variants at six loci were associated with Lp-PLA2 activity (PLA2G7, APOC1, CELSR2, LDL, ZNF259, SCARB1), among which the strongest signals were at rs4420638, near the APOE–APOC1–APOC4–APOC2 cluster [P = 4.9 × 10−30; log Lp-PLA2 difference per allele (beta): −0.054]. There were no significant gene–environment interactions between these eight polymorphisms associated with Lp-PLA2 mass or activity and age, sex, body mass index, or smoking status. Four of the polymorphisms (in APOC1, CELSR2, SCARB1, ZNF259), but not PLA2G7, were significantly associated with CHD in a second study.
Levels of Lp-PLA2 mass and activity were associated with PLA2G7, the gene coding for this protein. Lipoprotein-associated phospholipase A2 activity was also strongly associated with genetic variants related to low-density lipoprotein cholesterol levels.
PMCID: PMC3258449  PMID: 22003152
Genome-wide association; Inflammation; Lipoprotein-associated phospholipase A2
6.  Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure 
Wain, Louise V | Verwoert, Germaine C | O’Reilly, Paul F | Shi, Gang | Johnson, Toby | Johnson, Andrew D | Bochud, Murielle | Rice, Kenneth M | Henneman, Peter | Smith, Albert V | Ehret, Georg B | Amin, Najaf | Larson, Martin G | Mooser, Vincent | Hadley, David | Dörr, Marcus | Bis, Joshua C | Aspelund, Thor | Esko, Tõnu | Janssens, A Cecile JW | Zhao, Jing Hua | Heath, Simon | Laan, Maris | Fu, Jingyuan | Pistis, Giorgio | Luan, Jian’an | Arora, Pankaj | Lucas, Gavin | Pirastu, Nicola | Pichler, Irene | Jackson, Anne U | Webster, Rebecca J | Zhang, Feng | Peden, John F | Schmidt, Helena | Tanaka, Toshiko | Campbell, Harry | Igl, Wilmar | Milaneschi, Yuri | Hotteng, Jouke-Jan | Vitart, Veronique | Chasman, Daniel I | Trompet, Stella | Bragg-Gresham, Jennifer L | Alizadeh, Behrooz Z | Chambers, John C | Guo, Xiuqing | Lehtimäki, Terho | Kühnel, Brigitte | Lopez, Lorna M | Polašek, Ozren | Boban, Mladen | Nelson, Christopher P | Morrison, Alanna C | Pihur, Vasyl | Ganesh, Santhi K | Hofman, Albert | Kundu, Suman | Mattace-Raso, Francesco US | Rivadeneira, Fernando | Sijbrands, Eric JG | Uitterlinden, Andre G | Hwang, Shih-Jen | Vasan, Ramachandran S | Wang, Thomas J | Bergmann, Sven | Vollenweider, Peter | Waeber, Gérard | Laitinen, Jaana | Pouta, Anneli | Zitting, Paavo | McArdle, Wendy L | Kroemer, Heyo K | Völker, Uwe | Völzke, Henry | Glazer, Nicole L | Taylor, Kent D | Harris, Tamara B | Alavere, Helene | Haller, Toomas | Keis, Aime | Tammesoo, Mari-Liis | Aulchenko, Yurii | Barroso, Inês | Khaw, Kay-Tee | Galan, Pilar | Hercberg, Serge | Lathrop, Mark | Eyheramendy, Susana | Org, Elin | Sõber, Siim | Lu, Xiaowen | Nolte, Ilja M | Penninx, Brenda W | Corre, Tanguy | Masciullo, Corrado | Sala, Cinzia | Groop, Leif | Voight, Benjamin F | Melander, Olle | O’Donnell, Christopher J | Salomaa, Veikko | d’Adamo, Adamo Pio | Fabretto, Antonella | Faletra, Flavio | Ulivi, Sheila | Del Greco, M Fabiola | Facheris, Maurizio | Collins, Francis S | Bergman, Richard N | Beilby, John P | Hung, Joseph | Musk, A William | Mangino, Massimo | Shin, So-Youn | Soranzo, Nicole | Watkins, Hugh | Goel, Anuj | Hamsten, Anders | Gider, Pierre | Loitfelder, Marisa | Zeginigg, Marion | Hernandez, Dena | Najjar, Samer S | Navarro, Pau | Wild, Sarah H | Corsi, Anna Maria | Singleton, Andrew | de Geus, Eco JC | Willemsen, Gonneke | Parker, Alex N | Rose, Lynda M | Buckley, Brendan | Stott, David | Orru, Marco | Uda, Manuela | van der Klauw, Melanie M | Zhang, Weihua | Li, Xinzhong | Scott, James | Chen, Yii-Der Ida | Burke, Gregory L | Kähönen, Mika | Viikari, Jorma | Döring, Angela | Meitinger, Thomas | Davies, Gail | Starr, John M | Emilsson, Valur | Plump, Andrew | Lindeman, Jan H | ’t Hoen, Peter AC | König, Inke R | Felix, Janine F | Clarke, Robert | Hopewell, Jemma C | Ongen, Halit | Breteler, Monique | Debette, Stéphanie | DeStefano, Anita L | Fornage, Myriam | Mitchell, Gary F | Smith, Nicholas L | Holm, Hilma | Stefansson, Kari | Thorleifsson, Gudmar | Thorsteinsdottir, Unnur | Samani, Nilesh J | Preuss, Michael | Rudan, Igor | Hayward, Caroline | Deary, Ian J | Wichmann, H-Erich | Raitakari, Olli T | Palmas, Walter | Kooner, Jaspal S | Stolk, Ronald P | Jukema, J Wouter | Wright, Alan F | Boomsma, Dorret I | Bandinelli, Stefania | Gyllensten, Ulf B | Wilson, James F | Ferrucci, Luigi | Schmidt, Reinhold | Farrall, Martin | Spector, Tim D | Palmer, Lyle J | Tuomilehto, Jaakko | Pfeufer, Arne | Gasparini, Paolo | Siscovick, David | Altshuler, David | Loos, Ruth JF | Toniolo, Daniela | Snieder, Harold | Gieger, Christian | Meneton, Pierre | Wareham, Nicholas J | Oostra, Ben A | Metspalu, Andres | Launer, Lenore | Rettig, Rainer | Strachan, David P | Beckmann, Jacques S | Witteman, Jacqueline CM | Erdmann, Jeanette | van Dijk, Ko Willems | Boerwinkle, Eric | Boehnke, Michael | Ridker, Paul M | Jarvelin, Marjo-Riitta | Chakravarti, Aravinda | Abecasis, Goncalo R | Gudnason, Vilmundur | Newton-Cheh, Christopher | Levy, Daniel | Munroe, Patricia B | Psaty, Bruce M | Caulfield, Mark J | Rao, Dabeeru C | Tobin, Martin D | Elliott, Paul | van Duijn, Cornelia M
Nature genetics  2011;43(10):1005-1011.
Numerous genetic loci influence systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans 1-3. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N=74,064) and follow-up studies (N=48,607), we identified at genome-wide significance (P= 2.7×10-8 to P=2.3×10-13) four novel PP loci (at 4q12 near CHIC2/PDGFRAI, 7q22.3 near PIK3CG, 8q24.12 in NOV, 11q24.3 near ADAMTS-8), two novel MAP loci (3p21.31 in MAP4, 10q25.3 near ADRB1) and one locus associated with both traits (2q24.3 near FIGN) which has recently been associated with SBP in east Asians. For three of the novel PP signals, the estimated effect for SBP was opposite to that for DBP, in contrast to the majority of common SBP- and DBP-associated variants which show concordant effects on both traits. These findings indicate novel genetic mechanisms underlying blood pressure variation, including pathways that may differentially influence SBP and DBP.
PMCID: PMC3445021  PMID: 21909110
7.  Meta-analysis identifies six new susceptibility loci for atrial fibrillation 
Ellinor, Patrick T | Lunetta, Kathryn L | Albert, Christine M | Glazer, Nicole L | Ritchie, Marylyn D | Smith, Albert V | Arking, Dan E | Müller-Nurasyid, Martina | Krijthe, Bouwe P | Lubitz, Steven A | Bis, Joshua C | Chung, Mina K | Dörr, Marcus | Ozaki, Kouichi | Roberts, Jason D | Smith, J Gustav | Pfeufer, Arne | Sinner, Moritz F | Lohman, Kurt | Ding, Jingzhong | Smith, Nicholas L | Smith, Jonathan D | Rienstra, Michiel | Rice, Kenneth M | Van Wagoner, David R | Magnani, Jared W | Wakili, Reza | Clauss, Sebastian | Rotter, Jerome I | Steinbeck, Gerhard | Launer, Lenore J | Davies, Robert W | Borkovich, Matthew | Harris, Tamara B | Lin, Honghuang | Völker, Uwe | Völzke, Henry | Milan, David J | Hofman, Albert | Boerwinkle, Eric | Chen, Lin Y | Soliman, Elsayed Z | Voight, Benjamin F | Li, Guo | Chakravarti, Aravinda | Kubo, Michiaki | Tedrow, Usha B | Rose, Lynda M | Ridker, Paul M | Conen, David | Tsunoda, Tatsuhiko | Furukawa, Tetsushi | Sotoodehnia, Nona | Xu, Siyan | Kamatani, Naoyuki | Levy, Daniel | Nakamura, Yusuke | Parvez, Babar | Mahida, Saagar | Furie, Karen L | Rosand, Jonathan | Muhammad, Raafia | Psaty, Bruce M | Meitinger, Thomas | Perz, Siegfried | Wichmann, H-Erich | Witteman, Jacqueline C M | Kao, W H Linda | Kathiresan, Sekar | Roden, Dan M | Uitterlinden, Andre G | Rivadeneira, Fernando | McKnight, Barbara | Sjögren, Marketa | Newman, Anne B | Liu, Yongmei | Gollob, Michael H | Melander, Olle | Tanaka, Toshihiro | Ch Stricker, Bruno H | Felix, Stephan B | Alonso, Alvaro | Darbar, Dawood | Barnard, John | Chasman, Daniel I | Heckbert, Susan R | Benjamin, Emelia J | Gudnason, Vilmundur | Kääb, Stefan
Nature Genetics  2012;44(6):670-675.
Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death1. We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 1 0,030 subjects without atrial fibrillation (P < 5 × 10−8). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.
PMCID: PMC3366038  PMID: 22544366
8.  Genome-wide association analysis identifies multiple loci related to resting heart rate 
Eijgelsheim, Mark | Newton-Cheh, Christopher | Sotoodehnia, Nona | de Bakker, Paul I.W. | Müller, Martina | Morrison, Alanna C. | Smith, Albert V. | Isaacs, Aaron | Sanna, Serena | Dörr, Marcus | Navarro, Pau | Fuchsberger, Christian | Nolte, Ilja M. | de Geus, Eco J.C. | Estrada, Karol | Hwang, Shih-Jen | Bis, Joshua C. | Rückert, Ina-Maria | Alonso, Alvaro | Launer, Lenore J. | Hottenga, Jouke Jan | Rivadeneira, Fernando | Noseworthy, Peter A. | Rice, Kenneth M. | Perz, Siegfried | Arking, Dan E. | Spector, Tim D. | Kors, Jan A. | Aulchenko, Yurii S. | Tarasov, Kirill V. | Homuth, Georg | Wild, Sarah H. | Marroni, Fabio | Gieger, Christian | Licht, Carmilla M. | Prineas, Ronald J. | Hofman, Albert | Rotter, Jerome I. | Hicks, Andrew A. | Ernst, Florian | Najjar, Samer S. | Wright, Alan F. | Peters, Annette | Fox, Ervin R. | Oostra, Ben A. | Kroemer, Heyo K. | Couper, David | Völzke, Henry | Campbell, Harry | Meitinger, Thomas | Uda, Manuela | Witteman, Jacqueline C.M. | Psaty, Bruce M. | Wichmann, H-Erich | Harris, Tamara B. | Kääb, Stefan | Siscovick, David S. | Jamshidi, Yalda | Uitterlinden, André G. | Folsom, Aaron R. | Larson, Martin G. | Wilson, James F. | Penninx, Brenda W. | Snieder, Harold | Pramstaller, Peter P. | van Duijn, Cornelia M. | Lakatta, Edward G. | Felix, Stephan B. | Gudnason, Vilmundur | Pfeufer, Arne | Heckbert, Susan R. | Stricker, Bruno H.Ch. | Boerwinkle, Eric | O'Donnell, Christopher J.
Human Molecular Genetics  2010;19(19):3885-3894.
Higher resting heart rate is associated with increased cardiovascular disease and mortality risk. Though heritable factors play a substantial role in population variation, little is known about specific genetic determinants. This knowledge can impact clinical care by identifying novel factors that influence pathologic heart rate states, modulate heart rate through cardiac structure and function or by improving our understanding of the physiology of heart rate regulation. To identify common genetic variants associated with heart rate, we performed a meta-analysis of 15 genome-wide association studies (GWAS), including 38 991 subjects of European ancestry, estimating the association between age-, sex- and body mass-adjusted RR interval (inverse heart rate) and ∼2.5 million markers. Results with P < 5 × 10−8 were considered genome-wide significant. We constructed regression models with multiple markers to assess whether results at less stringent thresholds were likely to be truly associated with RR interval. We identified six novel associations with resting heart rate at six loci: 6q22 near GJA1; 14q12 near MYH7; 12p12 near SOX5, c12orf67, BCAT1, LRMP and CASC1; 6q22 near SLC35F1, PLN and c6orf204; 7q22 near SLC12A9 and UfSp1; and 11q12 near FADS1. Associations at 6q22 400 kb away from GJA1, at 14q12 MYH6 and at 1q32 near CD34 identified in previously published GWAS were confirmed. In aggregate, these variants explain ∼0.7% of RR interval variance. A multivariant regression model including 20 variants with P < 10−5 increased the explained variance to 1.6%, suggesting that some loci falling short of genome-wide significance are likely truly associated. Future research is warranted to elucidate underlying mechanisms that may impact clinical care.
PMCID: PMC3657480  PMID: 20639392
9.  Quality control and quality assurance in genotypic data for genome-wide association studies 
Genetic epidemiology  2010;34(6):591-602.
Genome-wide scans of nucleotide variation in human subjects are providing an increasing number of replicated associations with complex disease traits. Most of the variants detected have small effects and, collectively, they account for a small fraction of the total genetic variance. Very large sample sizes are required to identify and validate findings. In this situation, even small sources of systematic or random error can cause spurious results or obscure real effects. The need for careful attention to data quality has been appreciated for some time in this field, and a number of strategies for quality control and quality assurance (QC/QA) have been developed. Here we extend these methods and describe a system of QC/QA for genotypic data in genome-wide association studies. This system includes some new approaches that (1) combine analysis of allelic probe intensities and called genotypes to distinguish gender misidentification from sex chromosome aberrations, (2) detect autosomal chromosome aberrations that may affect genotype calling accuracy, (3) infer DNA sample quality from relatedness and allelic intensities, (4) use duplicate concordance to infer SNP quality, (5) detect genotyping artifacts from dependence of Hardy-Weinberg equilibrium (HWE) test p-values on allelic frequency, and (6) demonstrate sensitivity of principal components analysis (PCA) to SNP selection. The methods are illustrated with examples from the ‘Gene Environment Association Studies’ (GENEVA) program. The results suggest several recommendations for QC/QA in the design and execution of genome-wide association studies.
PMCID: PMC3061487  PMID: 20718045
GWAS; DNA sample quality; genotyping artifact; Hardy-Weinberg equilibrium; chromosome aberration
10.  The Association of Genome-Wide Variation with the Risk of Incident Heart Failure in Adults of European and African Ancestry: A Prospective Meta-Analysis from the CHARGE Consortium 
Although genetic factors contribute to the onset of heart failure (HF), no large-scale genome-wide investigation of HF risk has been published to date. We investigated the association of 2,478,304 single nucleotide polymorphisms (SNPs) with incident HF by meta-analyzing data from 4 community-based prospective cohorts: the Atherosclerosis Risk in Communities Study, the Cardiovascular Health Study, the Framingham Heart Study, and the Rotterdam Study.
Methods and Results
Eligible participants for these analyses were of European or African ancestry and free of clinical HF at baseline. Each study independently conducted genome-wide scans and imputed data to the ~2.5 million SNPs in HapMap. Within each study, Cox proportional hazards regression models provided age- and sex-adjusted estimates of the association between each variant and time to incident HF. Fixed-effect meta-analyses combined results for each SNP from the 4 cohorts to produce an overall association estimate and p-value. A genome-wide significance p-value threshold was set a priori at 5.0×10−7. During a mean follow-up of 11.5 years, 2,526 incident HF events (12%) occurred in 20,926 European-ancestry participants. The meta-analysis identified a genome-wide significant locus at chromosomal position 15q22 (1.4×10−8), which was 58.8 kb from USP3. Among 2,895 African-ancestry participants, 466 incident HF events (16%) occurred during a mean follow-up of 13.7 years. One genome-wide significant locus was identified at 12q14 (6.7×10−8), which was 6.3 kb from LRIG3.
We identified 2 loci that were associated with incident HF and exceeded genome-wide significance. The findings merit replication in other community-based settings of incident HF.
PMCID: PMC3025695  PMID: 20445134
epidemiology; genetics; heart failure; genome-wide variation; incidence
11.  Genomic variation associated with mortality among adults of European and African ancestry with heart failure: the CHARGE Consortium 
Prognosis and survival are significant concerns for individuals with heart failure (HF). In order to better understand the pathophysiology of HF prognosis, the association between 2,366,858 single nucleotide polymorphisms (SNPs) and all-cause mortality was evaluated among individuals with incident HF from four community-based prospective cohorts: the Atherosclerosis Risk in Communities Study, the Cardiovascular Health Study, the Framingham Heart Study, and the Rotterdam Study.
Methods and Results
Participants were 2,526 individuals of European ancestry and 466 individuals of African ancestry who suffered an incident HF event during follow-up in the respective cohorts. Within each study, the association between genetic variants and time to mortality among individuals with HF was assessed by Cox proportional hazards models that included adjustment for sex and age at the time of the HF event. Prospective fixed-effect meta-analyses were conducted for the four study populations of European ancestry (N=1,645 deaths) and for the two populations of African ancestry (N=281 deaths). Genome-wide significance was set at P=5.0×10-7. Meta-analytic findings among individuals of European ancestry revealed one genome-wide significant locus on chromosome 3p22 in an intron of CKLF-like MARVEL transmembrane domain containing 7 (CMTM7, p = 3.2×10-7). Eight additional loci in individuals of European ancestry and four loci in individuals of African ancestry were identified by high-signal SNPs (p < 1.0×10-5), but did not meet genome-wide significance.
This study identified a novel locus associated with all-cause mortality among individuals of European ancestry with HF. This finding warrants additional investigation, including replication, in other studies of HF.
PMCID: PMC3033765  PMID: 20400778
heart failure; all-cause mortality; genetics; genome-wide variation
12.  Comparing self-reported ethnicity to genetic background measures in the context of the Multi-Ethnic Study of Atherosclerosis (MESA) 
BMC Genetics  2011;12:28.
Questions remain regarding the utility of self-reported ethnicity (SRE) in genetic and epidemiologic research. It is not clear whether conditioning on SRE provides adequate protection from inflated type I error rates due to population stratification and admixture. We address this question using data obtained from the Multi-Ethnic Study of Atherosclerosis (MESA), which enrolled individuals from 4 self-reported ethnic groups. We compare the agreement between SRE and genetic based measures of ancestry (GBMA), and conduct simulation studies based on observed MESA data to evaluate the performance of each measure under various conditions.
Four clusters are identified using 96 ancestry informative markers. Three of these clusters are well delineated, but 30% of the self-reported Hispanic-Americans are misclassified. We also found that MESA SRE provides type I error rates that are consistent with the nominal levels. More extensive simulations revealed that this finding is likely due to the multi-ethnic nature of the MESA. Finally, we describe situations where SRE may perform as well as a GBMA in controlling the effect of population stratification and admixture in association tests.
The performance of SRE as a control variable in genetic association tests is more nuanced than previously thought, and may have more value than it is currently credited with, especially when smaller replication studies are being considered in multi-ethnic samples.
PMCID: PMC3068121  PMID: 21375750
13.  Association of genetic variation with systolic and diastolic blood pressure among African Americans: the Candidate Gene Association Resource study 
Fox, Ervin R. | Young, J. Hunter | Li, Yali | Dreisbach, Albert W. | Keating, Brendan J. | Musani, Solomon K. | Liu, Kiang | Morrison, Alanna C. | Ganesh, Santhi | Kutlar, Abdullah | Ramachandran, Vasan S. | Polak, Josef F. | Fabsitz, Richard R. | Dries, Daniel L. | Farlow, Deborah N. | Redline, Susan | Adeyemo, Adebowale | Hirschorn, Joel N. | Sun, Yan V. | Wyatt, Sharon B. | Penman, Alan D. | Palmas, Walter | Rotter, Jerome I. | Townsend, Raymond R. | Doumatey, Ayo P. | Tayo, Bamidele O. | Mosley, Thomas H. | Lyon, Helen N. | Kang, Sun J. | Rotimi, Charles N. | Cooper, Richard S. | Franceschini, Nora | Curb, J. David | Martin, Lisa W. | Eaton, Charles B. | Kardia, Sharon L.R. | Taylor, Herman A. | Caulfield, Mark J. | Ehret, Georg B. | Johnson, Toby | Chakravarti, Aravinda | Zhu, Xiaofeng | Levy, Daniel | Munroe, Patricia B. | Rice, Kenneth M. | Bochud, Murielle | Johnson, Andrew D. | Chasman, Daniel I. | Smith, Albert V. | Tobin, Martin D. | Verwoert, Germaine C. | Hwang, Shih-Jen | Pihur, Vasyl | Vollenweider, Peter | O'Reilly, Paul F. | Amin, Najaf | Bragg-Gresham, Jennifer L. | Teumer, Alexander | Glazer, Nicole L. | Launer, Lenore | Zhao, Jing Hua | Aulchenko, Yurii | Heath, Simon | Sõber, Siim | Parsa, Afshin | Luan, Jian'an | Arora, Pankaj | Dehghan, Abbas | Zhang, Feng | Lucas, Gavin | Hicks, Andrew A. | Jackson, Anne U. | Peden, John F. | Tanaka, Toshiko | Wild, Sarah H. | Rudan, Igor | Igl, Wilmar | Milaneschi, Yuri | Parker, Alex N. | Fava, Cristiano | Chambers, John C. | Kumari, Meena | JinGo, Min | van der Harst, Pim | Kao, Wen Hong Linda | Sjögren, Marketa | Vinay, D.G. | Alexander, Myriam | Tabara, Yasuharu | Shaw-Hawkins, Sue | Whincup, Peter H. | Liu, Yongmei | Shi, Gang | Kuusisto, Johanna | Seielstad, Mark | Sim, Xueling | Nguyen, Khanh-Dung Hoang | Lehtimäki, Terho | Matullo, Giuseppe | Wu, Ying | Gaunt, Tom R. | Charlotte Onland-Moret, N. | Cooper, Matthew N. | Platou, Carl G.P. | Org, Elin | Hardy, Rebecca | Dahgam, Santosh | Palmen, Jutta | Vitart, Veronique | Braund, Peter S. | Kuznetsova, Tatiana | Uiterwaal, Cuno S.P.M. | Campbell, Harry | Ludwig, Barbara | Tomaszewski, Maciej | Tzoulaki, Ioanna | Palmer, Nicholette D. | Aspelund, Thor | Garcia, Melissa | Chang, Yen-Pei C. | O'Connell, Jeffrey R. | Steinle, Nanette I. | Grobbee, Diederick E. | Arking, Dan E. | Hernandez, Dena | Najjar, Samer | McArdle, Wendy L. | Hadley, David | Brown, Morris J. | Connell, John M. | Hingorani, Aroon D. | Day, Ian N.M. | Lawlor, Debbie A. | Beilby, John P. | Lawrence, Robert W. | Clarke, Robert | Collins, Rory | Hopewell, Jemma C. | Ongen, Halit | Bis, Joshua C. | Kähönen, Mika | Viikari, Jorma | Adair, Linda S. | Lee, Nanette R. | Chen, Ming-Huei | Olden, Matthias | Pattaro, Cristian | Hoffman Bolton, Judith A. | Köttgen, Anna | Bergmann, Sven | Mooser, Vincent | Chaturvedi, Nish | Frayling, Timothy M. | Islam, Muhammad | Jafar, Tazeen H. | Erdmann, Jeanette | Kulkarni, Smita R. | Bornstein, Stefan R. | Grässler, Jürgen | Groop, Leif | Voight, Benjamin F. | Kettunen, Johannes | Howard, Philip | Taylor, Andrew | Guarrera, Simonetta | Ricceri, Fulvio | Emilsson, Valur | Plump, Andrew | Barroso, Inês | Khaw, Kay-Tee | Weder, Alan B. | Hunt, Steven C. | Bergman, Richard N. | Collins, Francis S. | Bonnycastle, Lori L. | Scott, Laura J. | Stringham, Heather M. | Peltonen, Leena | Perola, Markus | Vartiainen, Erkki | Brand, Stefan-Martin | Staessen, Jan A. | Wang, Thomas J. | Burton, Paul R. | SolerArtigas, Maria | Dong, Yanbin | Snieder, Harold | Wang, Xiaoling | Zhu, Haidong | Lohman, Kurt K. | Rudock, Megan E. | Heckbert, Susan R. | Smith, Nicholas L. | Wiggins, Kerri L. | Shriner, Daniel | Veldre, Gudrun | Viigimaa, Margus | Kinra, Sanjay | Prabhakaran, Dorairajan | Tripathy, Vikal | Langefeld, Carl D. | Rosengren, Annika | Thelle, Dag S. | MariaCorsi, Anna | Singleton, Andrew | Forrester, Terrence | Hilton, Gina | McKenzie, Colin A. | Salako, Tunde | Iwai, Naoharu | Kita, Yoshikuni | Ogihara, Toshio | Ohkubo, Takayoshi | Okamura, Tomonori | Ueshima, Hirotsugu | Umemura, Satoshi | Eyheramendy, Susana | Meitinger, Thomas | Wichmann, H.-Erich | Cho, Yoon Shin | Kim, Hyung-Lae | Lee, Jong-Young | Scott, James | Sehmi, Joban S. | Zhang, Weihua | Hedblad, Bo | Nilsson, Peter | Smith, George Davey | Wong, Andrew | Narisu, Narisu | Stančáková, Alena | Raffel, Leslie J. | Yao, Jie | Kathiresan, Sekar | O'Donnell, Chris | Schwartz, Steven M. | Arfan Ikram, M. | Longstreth, Will T. | Seshadri, Sudha | Shrine, Nick R.G. | Wain, Louise V. | Morken, Mario A. | Swift, Amy J. | Laitinen, Jaana | Prokopenko, Inga | Zitting, Paavo | Cooper, Jackie A. | Humphries, Steve E. | Danesh, John | Rasheed, Asif | Goel, Anuj | Hamsten, Anders | Watkins, Hugh | Bakker, Stephan J.L. | van Gilst, Wiek H. | Janipalli, Charles S. | Radha Mani, K. | Yajnik, Chittaranjan S. | Hofman, Albert | Mattace-Raso, Francesco U.S. | Oostra, Ben A. | Demirkan, Ayse | Isaacs, Aaron | Rivadeneira, Fernando | Lakatta, Edward G. | Orru, Marco | Scuteri, Angelo | Ala-Korpela, Mika | Kangas, Antti J. | Lyytikäinen, Leo-Pekka | Soininen, Pasi | Tukiainen, Taru | Würz, Peter | Twee-Hee Ong, Rick | Dörr, Marcus | Kroemer, Heyo K. | Völker, Uwe | Völzke, Henry | Galan, Pilar | Hercberg, Serge | Lathrop, Mark | Zelenika, Diana | Deloukas, Panos | Mangino, Massimo | Spector, Tim D. | Zhai, Guangju | Meschia, James F. | Nalls, Michael A. | Sharma, Pankaj | Terzic, Janos | Kranthi Kumar, M.J. | Denniff, Matthew | Zukowska-Szczechowska, Ewa | Wagenknecht, Lynne E. | Fowkes, Gerald R. | Charchar, Fadi J. | Schwarz, Peter E.H. | Hayward, Caroline | Guo, Xiuqing | Bots, Michiel L. | Brand, Eva | Samani, Nilesh J. | Polasek, Ozren | Talmud, Philippa J. | Nyberg, Fredrik | Kuh, Diana | Laan, Maris | Hveem, Kristian | Palmer, Lyle J. | van der Schouw, Yvonne T. | Casas, Juan P. | Mohlke, Karen L. | Vineis, Paolo | Raitakari, Olli | Wong, Tien Y. | Shyong Tai, E. | Laakso, Markku | Rao, Dabeeru C. | Harris, Tamara B. | Morris, Richard W. | Dominiczak, Anna F. | Kivimaki, Mika | Marmot, Michael G. | Miki, Tetsuro | Saleheen, Danish | Chandak, Giriraj R. | Coresh, Josef | Navis, Gerjan | Salomaa, Veikko | Han, Bok-Ghee | Kooner, Jaspal S. | Melander, Olle | Ridker, Paul M. | Bandinelli, Stefania | Gyllensten, Ulf B. | Wright, Alan F. | Wilson, James F. | Ferrucci, Luigi | Farrall, Martin | Tuomilehto, Jaakko | Pramstaller, Peter P. | Elosua, Roberto | Soranzo, Nicole | Sijbrands, Eric J.G. | Altshuler, David | Loos, Ruth J.F. | Shuldiner, Alan R. | Gieger, Christian | Meneton, Pierre | Uitterlinden, Andre G. | Wareham, Nicholas J. | Gudnason, Vilmundur | Rettig, Rainer | Uda, Manuela | Strachan, David P. | Witteman, Jacqueline C.M. | Hartikainen, Anna-Liisa | Beckmann, Jacques S. | Boerwinkle, Eric | Boehnke, Michael | Larson, Martin G. | Järvelin, Marjo-Riitta | Psaty, Bruce M. | Abecasis, Gonçalo R. | Elliott, Paul | van Duijn , Cornelia M. | Newton-Cheh, Christopher
Human Molecular Genetics  2011;20(11):2273-2284.
The prevalence of hypertension in African Americans (AAs) is higher than in other US groups; yet, few have performed genome-wide association studies (GWASs) in AA. Among people of European descent, GWASs have identified genetic variants at 13 loci that are associated with blood pressure. It is unknown if these variants confer susceptibility in people of African ancestry. Here, we examined genome-wide and candidate gene associations with systolic blood pressure (SBP) and diastolic blood pressure (DBP) using the Candidate Gene Association Resource (CARe) consortium consisting of 8591 AAs. Genotypes included genome-wide single-nucleotide polymorphism (SNP) data utilizing the Affymetrix 6.0 array with imputation to 2.5 million HapMap SNPs and candidate gene SNP data utilizing a 50K cardiovascular gene-centric array (ITMAT-Broad-CARe [IBC] array). For Affymetrix data, the strongest signal for DBP was rs10474346 (P= 3.6 × 10−8) located near GPR98 and ARRDC3. For SBP, the strongest signal was rs2258119 in C21orf91 (P= 4.7 × 10−8). The top IBC association for SBP was rs2012318 (P= 6.4 × 10−6) near SLC25A42 and for DBP was rs2523586 (P= 1.3 × 10−6) near HLA-B. None of the top variants replicated in additional AA (n = 11 882) or European-American (n = 69 899) cohorts. We replicated previously reported European-American blood pressure SNPs in our AA samples (SH2B3, P= 0.009; TBX3-TBX5, P= 0.03; and CSK-ULK3, P= 0.0004). These genetic loci represent the best evidence of genetic influences on SBP and DBP in AAs to date. More broadly, this work supports that notion that blood pressure among AAs is a trait with genetic underpinnings but also with significant complexity.
PMCID: PMC3090190  PMID: 21378095
14.  Short term and long term risk of incident ischemic stroke after transient ischemic attack 
Background and purpose
The relative risk of ischemic stroke associated with transient ischemic attack (TIA) is not well-defined because most studies of stroke after TIA did not include comparison groups. We sought to estimate short term and long term relative risks of ischemic stroke associated with clinically diagnosed TIA.
We used data from a population-based case-control study. Cases were hypertensive men and women, and postmenopausal women, ages 30–79, with incident ischemic stroke. Controls were sampled within strata of age, sex, hypertension status, and calendar year. The index date was the stroke date for cases and a random date for controls. Clinically diagnosed TIA was ascertained from medical records. We used logistic regression to calculate odds ratios (ORs).
The study included 1,914 stroke cases and 9,874 controls. Clinically diagnosed TIA was present in 215 (11.2%) cases and 252 (2.5%) controls. Analyses focused on the most recent TIA before index date. For TIA <1 month before index date, the adjusted OR for stroke was 30.4 (95% CI: 10.4, 89.4); for TIA 1–3 months before index date, it was 18.9 (8.58, 41.6); for TIA 4–6 months before index date, it was 3.16 (1.27, 7.82); and for TIA more than five years before index date, it was 1.87 (1.22, 2.85).
The relative risk of ischemic stroke was high for TIA diagnosed within the past three months, and moderately high for TIA diagnosed more than five years in the past, compared with no history of clinically diagnosed TIA.
PMCID: PMC2818812  PMID: 19959534
stroke; transient ischemic attack; epidemiology; case-control study
15.  Discovering Novel Risk Factors for Venous Thrombosis: a Candidate-Gene Approach 
Thrombosis research  2009;123(Suppl 4):S25-S29.
The candidate-gene approach can be used to locate and identify genetic variations that are associated with a particular phenotype. This gene-centric approach assumes that there exists important genetic variation within genes that can influence health. Identifying known genes which are candidates for the phenotype of interest can be accomplished using existing knowledge about biology or using findings from genome-wide association studies. Genetic variation can be characterized locally by single nucleotide polymorphisms (SNPs) or insertiondeletions, or it can be characterized more broadly in terms of haplotypes and diplotypes, which usually need to be inferred statistically. As an example, we present a candidate-gene approach to identify novel associations between variation in 24 clotting genes and the risk of incident venous thrombosis.
PMCID: PMC2987733  PMID: 19303500
17.  Factors Associated With Low Levels of Subclinical Vascular Disease in Older Adults: Multi-Ethnic Study of Atherosclerosis 
Preventive cardiology  2009;12(2):72-79.
Coronary artery calcium (CAC), carotid intimal medial thickness (cIMT), and reduced ankle brachial indices (ABI) are markers of subclinical vascular disease strongly associated with aging. We identified factors associated with low levels of subclinical vascular disease in 1824 participants ≥70 years in the Multi-Ethnic Study of Atherosclerosis. 452 had low CAC (<25th percentile), 441 had low cIMT (<25th percentile), 1636 had normal ABI (>0.9), and 165 had a combination index indicating favorable values for all three parameters. This combination index was independently associated with younger age [OR=2.5 per 1 SD (95%CI 1.8–3.6)], female gender [OR=3.0(1.9–4.8)], lower BMI [OR=1.6 per 1 SD (1.2–2.0)], absence of hypertension [OR=1.8(1.2–2.6)], absence of dyslipidemia [OR=1.6 (1.04–2.4)], and never smoking [OR=1.7(1.1–2.6)]. No significant associations were observed for C-reactive protein, education, diet, or physical activity. Favorable levels of multiple traditional risk factors, but not several novel risk factors, were associated with subclinical markers of successful cardiovascular aging.
PMCID: PMC2932469  PMID: 19476580
18.  Genetic Variation in ACE-related pathways associated with Sudden Cardiac Arrest Risk 
Angiotensin converting enzyme (ACE)-related pathways influence arrhythmias and sudden cardiac arrest (SCA) risk.
We investigated whether genetic variation in ACE-related pathways are associated with SCA risk. Because these pathways are sex-dependent and influenced by estrogen, we examined these genotype-SCA associations in the full study population, and tested for interaction with gender.
In a population-based case-control study set in King County WA, we genotyped 211 SCA cases (mean age 59, 80% male) and 730 age- and gender-matched controls of European descent for 47 single nucleotide polymorphisms (SNPs) in eight genes (ACE, AGT, REN, AGTR1, AGTR2, ACE2, KNG1, BDKRB2). We examined association of SNPs and haplotypes with SCA risk using logistic regression.
AGTR1 SNP rs1492099 (allele frequency=15%) was associated with decreased SCA risk (OR=0.62, 95%CI=0.4–0.9). Haplotype variation in AGTR2 was associated with SCA risk (global haplotype test p=0.001), with haplotype 2 (allele frequency=27%) associated with increased risk (OR=1.26, 95%CI=1.1–1.5). There was interaction with gender on SCA risk for variation in KNG1 (interaction p-value range=0.0004–0.017 for 6/8 SNPs). KNG1 SNP rs710448 (allele frequency=42%) was associated with decreased risk (OR=0.44, 95%CI=0.3–0.8) among women but not men. Other SNPs and haplotypes in the eight genes examined were not associated with SCA risk after multiple testing correction.
Variation in AGTR1 and AGTR2 are associated with SCA risk in a population-based case-control study. There was evidence of interaction with gender on SCA risk for variation in KNG1. Our findings, if replicated, suggest that variation in genes in ACE-related pathways influence SCA risk.
PMCID: PMC2757102  PMID: 19716087
sudden death; cardiac arrest; epidemiology; genetics; polymorphism; renin-angiotensin system
19.  Common Variants in KCNN3 are Associated with Lone Atrial Fibrillation 
Nature genetics  2010;42(3):240-244.
Atrial fibrillation (AF) is the most common sustained arrhythmia. A subset of patients with lone AF have no overt heart disease and an increased heritability of AF. We sought to identify common genetic variants underlying lone AF. Cases were from the German AF Network, Heart and Vascular Health Study, Atherosclerosis Risk in Communities Study, Cleveland Clinic, and Massachusetts General Hospital. Subjects were genotyped, HapMap SNPs imputed, and age- sex- and hypertension-adjusted analyses performed. A meta-analysis was conducted using 1,335 cases of lone AF and 12,844 referents. A novel locus on chromosome 1q21 was identified, and the most significant SNP, rs13376333, had an adjusted odds ratio of 1.56 (P=6.3×10−12). This association was replicated in two cohorts with lone AF for an overall odds ratio of 1.52 (P=1.83×10−21). Rs13376333 is intronic to KCNN3, a potassium channel involved in atrial repolarization. KCNN3 represents a novel potential therapeutic target in the treatment of AF.
PMCID: PMC2871387  PMID: 20173747
20.  Variants in ZFHX3 are associated with atrial fibrillation in individuals of European ancestry 
Nature genetics  2009;41(8):879-881.
We conducted meta-analyses of genome-wide association studies (GWAS) for atrial fibrillation (AF) in participants from five community-based cohorts. Meta-analyses of 896 prevalent (15,768 referents) and 2,517 incident (21,337 referents) AF cases identified a novel locus for AF (ZFHX3, rs2106261, risk ratio [RR]=1.19; P=2.3×10−7), an association that was replicated in the German AF Network (odds ratio=1.44; P=1.6×10−11). Combining the discovery and replication results, rs2106261 was significantly associated with AF (RR=1.25; P=1.8×10−15).
PMCID: PMC2761746  PMID: 19597492
atrial fibrillation; epidemiology; genetics; polymorphism; single nucleotide
21.  Myocardial infarction and stroke associated with diuretic based two drug antihypertensive regimens: population based case-control study 
Objective To examine the association of myocardial infarction and stroke incidence with several commonly used two drug antihypertensive treatment regimens.
Design Population based case-control study.
Setting Group Health Cooperative, Seattle, WA, USA.
Participants Cases (n=353) were aged 30-79 years, had pharmacologically treated hypertension, and were diagnosed with a first fatal or non-fatal myocardial infarction or stroke between 1989 and 2005. Controls (n=952) were a random sample of Group Health members who had pharmacologically treated hypertension. We excluded individuals with heart failure, evidence of coronary heart disease, diabetes, or chronic kidney disease.
Exposures One of three common two drug combinations: diuretics plus β blockers; diuretics plus calcium channel blockers; and diuretics plus angiotensin converting enzyme inhibitors or angiotensin receptor blockers.
Main outcome measures Myocardial infarction or stroke.
Results Compared with users of diuretics plus β blockers, users of diuretics plus calcium channel blockers had an increased risk of myocardial infarction (adjusted odds ratio (OR) 1.98, 95% confidence interval 1.37 to 2.87) but not of stroke (OR 1.02, 95% CI 0.63 to 1.64). The risks of myocardial infarction and stroke in users of diuretics plus angiotensin converting enzyme inhibitors or angiotensin receptor blockers were slightly but not significantly lower than in users of diuretics plus β blockers (myocardial infarction: OR 0.76, 95% CI 0.52 to 1.11; stroke: OR 0.71, 95% CI 0.46 to 1.10).
Conclusions In patients with hypertension, diuretics plus calcium channel blockers were associated with a higher risk of myocardial infarction than other common two drug treatment regimens. A large trial of second line antihypertensive treatments in patients already on low dose diuretics is required to provide a solid basis for treatment recommendations.
PMCID: PMC2811239  PMID: 20100777
22.  Motivating factors for physician ordering of Factor V Leiden genetic tests 
Archives of internal medicine  2009;169(1):68-74.
The Factor V Leiden (FVL) genetic test is used by many physicians despite its uncertain clinical utility. This study investigated whether self-reported motivations and behaviors concerning FVL genetic testing differed between two groups of primary care physicians defined by frequency of prior FVL test use.
In January 2007, 112 primary care physicians (60 frequent, 52 infrequent FVL test users) at Group Health, a large health care delivery system, were surveyed. Survey content areas included: primary reasons and motivating factors for ordering FVL; likelihood of ordering FVL for hypothetical patients; potential barriers to genetic testing, and practices and skills regarding FVL test ordering.
Responses between groups agreed concerning most clinical- or patient-related factors. Frequent-FVL physicians were more likely than infrequent-FVL physicians to report ordering FVL for hypothetical patients with mesenteric venous thrombosis (adjusted OR 4.57, 95% CI 1.55, 13.53) or venous thrombosis following hospital discharge (adjusted OR 3.42, 95% CI 1.30, 8.95). Frequent-FVL physicians were also less likely to agree with several potential barriers to genetic testing and more likely to report high confidence in interpreting and explaining FVL test results.
Generally, both groups of physicians reported similar motivating factors for ordering FVL, and reported behaviors were consistent with existing guidelines. More striking differences were observed for measures such as barriers to and confidence in using genetic tests. Though additional research is necessary to evaluate their impact, these results inform several knowledge-to-practice translation issues that are important to the successful integration of genetic testing into primary care.
PMCID: PMC2651814  PMID: 19139326
23.  Common genetic variation in six lipid- and statin-related genes, statin use and risk of incident nonfatal myocardial infarction and stroke 
Pharmacogenetics and genomics  2008;18(8):677-682.
Genetic polymorphisms are associated with lipid-lowering response to statins, but generalizeability to disease endpoints is unclear. The association between 82 common single nucleotide polymorphisms (SNPs) in 6 lipid- or statin-related genes (ABCB1, CETP, HMGCR, LDLR, LIPC, NOS3) and incident nonfatal myocardial infarction (MI) and ischemic stroke was analyzed according to current statin use and overall in a population-based case-control study (856 MI, 368 stroke, 2686 controls).
Common SNPs were chosen from resequencing data using pairwise linkage disequilibrium. Gene-level analyses (testing global association within a gene) and SNP-level analyses (comparing the number of observed versus expected associations across all genes) were performed using logistic regression, setting nominal statistical significance at p<0.05.
No gene-level interactions with statin use on MI or stroke were identified. Across all genes, 2 SNP-statin interactions on MI were observed (1 ABCB1, 1 LIPC) and 5 interactions on stroke (1 CETP, 4 LIPC). The strongest SNP-statin interaction was for synonymous CETP SNP rs5883 on stroke (p = 0.008). Gene-level associations were present for LIPC and MI (p = 0.026), but not other genes or outcomes. SNP-level associations included 3 SNPs with MI (1 LDLR, 2 LIPC) and 2 SNPs with stroke (1 CETP, 1 LDLR). The number of observed SNP associations was no greater than expected by chance.
Several potential novel associations or interactions of SNPs in ABCB1, CETP, LDLR and LIPC with MI and stroke were identified; however, our results should be regarded as hypothesis-generating until corroborated by other studies.
PMCID: PMC2736793  PMID: 18622260
Pharmacogenetics; epidemiology; myocardial infarction; stroke; statins; HMG-CoA
24.  Cholesterol Ester Transfer Protein, Interleukin 8, Peroxisome Proliferator Activator Receptor Alpha and Toll-Like Receptor 4 Genetic Variations and Risk of Incident Non-Fatal Myocardial Infarction and Ischemic Stroke 
The American journal of cardiology  2008;101(12):1683-1688.
Variations in candidate genes participating in oxidative stress, inflammation and their interactions are potentially associated with diseases of atherosclerotic origin. We investigated independent and joint associations of variations in cholesterol ester transfer protein (CETP), interleukin 8 (IL8), peroxisome proliferator activator receptor alpha (PPARA) and toll-like receptor 4 (TLR4) genes with incident non-fatal myocardial infarction (MI) or ischemic stroke. In a population-based case-control study, cases (848 MI and 368 ischemic stroke) and controls (2682) were recruited from postmenopausal women and hypertensive men/women who were members of Group Health in Western Washington State. Common tag single nucleotide polymorphisms (n=34) representing gene-wide variations were selected from gene sequencing data using pairwise linkage disequilibrium. Haplotypes were inferred using a modified expectation maximization algorithm. Multivariate logistic regression evaluated individual haplotype and SNP-disease associations in log-additive models. Global haplotype tests assessed overall gene-disease associations. Logic regression was used to evaluate gene-gene interactions. False discovery rates and permutation tests were used for multiple testing adjustment in evaluating independent associations and interactions respectively. Overall, gene-wide variations in PPARA and TLR4 genes were associated with MI. The minor allele of the PPARA SNP, rs4253623, was associated with a higher risk of MI (odds ratio: 1.25, 95%CI: 1.08–1.46) while the minor allele of the TLR4 SNP, rs1927911, was associated with a lower risk of MI (odds ratio: 0.88, 95%CI: 0.77–0.99). No within gene or gene-gene interaction was associated with MI or ischemic stroke risk. Potential SNP-disease associations identified in the current study are novel.
PMCID: PMC2577871  PMID: 18549840
genetic risk factors; myocardial infarction; ischemic stroke
25.  Common variants in the CRP gene in relation to longevity and cause-specific mortality in older adults: the Cardiovascular Health Study 
Atherosclerosis  2007;197(2):922-930.
Common polymorphisms in the CRP gene are associated with plasma CRP levels in population-based studies, but associations with age-related events are uncertain. A previous study of CRP haplotypes in older adults was broadened to include longevity and cause-specific mortality (all-cause, non-cardiovascular (nonCV), and cardiovascular (CV)). Common haplotypes were inferred from four tagSNPs in 4512 whites and five tagSNPs in 812 blacks from the Cardiovascular Health Study, a longitudinal cohort of adults over age 65. Exploratory analyses addressed early versus late mortality. CRP haplotypes were not associated with all-cause mortality or longevity overall in either population, but associations with all-cause mortality differed during early and late periods. In blacks, the haplotype tagged by 3872A (rs1205) was associated with increased risk of nonCV mortality, relative to other haplotypes (adjusted hazard ratio for each additional copy: 1.42, 95% CI: 1.07, 1.87). Relative to other haplotypes, this haplotype was associated with decreased risk of early but not decreased risk of late CV mortality in blacks; among whites, a haplotype tagged by 2667C (rs1800947) gave similar but nonsignificant findings. If confirmed, CRP genetic variants may be weakly associated with CV and nonCV mortality in older adults, particularly in self-identified blacks.
PMCID: PMC2362133  PMID: 17888441

Results 1-25 (25)