Faculty Bibliography
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527
Trans-ethnic fine-mapping of lipid loci identifies population-specific signals and allelic heterogeneity that increases the trait variance explained
Genome-wide association studies (GWAS) have identified ~100 loci associated with blood lipid levels, but much of the trait heritability remains unexplained, and at most loci the identities of the trait-influencing variants remain unknown. We conducted a trans-ethnic fine-mapping study at 18, 22, and 18 GWAS loci on the Metabochip for their association with triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), respectively, in individuals of African American (n = 6,832), East Asian (n = 9,449), and European (n = 10,829) ancestry. We aimed to identify the variants with strongest association at each locus, identify additional and population-specific signals, refine association signals, and assess the relative significance of previously described functional variants. Among the 58 loci, 33 exhibited evidence of association at P<1 x 10(-4) in at least one ancestry group. Sequential conditional analyses revealed that ten, nine, and four loci in African Americans, Europeans, and East Asians, respectively, exhibited two or more signals. At these loci, accounting for all signals led to a 1.3- to 1.8-fold increase in the explained phenotypic variance compared to the strongest signals. Distinct signals across ancestry groups were identified at PCSK9 and APOA5. Trans-ethnic analyses narrowed the signals to smaller sets of variants at GCKR, PPP1R3B, ABO, LCAT, and ABCA1. Of 27 variants reported previously to have functional effects, 74% exhibited the strongest association at the respective signal. In conclusion, trans-ethnic high-density genotyping and analysis confirm the presence of allelic heterogeneity, allow the identification of population-specific variants, and limit the number of candidate SNPs for functional studies.
PMCID:3605054
PMID: 23555291
ISSN: 1553-7404
CID: 2747062
Associations between NOS1AP single nucleotide polymorphisms (SNPs) and QT interval duration in four racial/ethnic groups in the Multi-Ethnic Study of Atherosclerosis (MESA)
BACKGROUNDS: QT is a risk factor for sudden cardiac death (SCD). A genome-wide association study identified NOS1AP variants associated with QT, which have been replicated in predominantly Caucasian (CAU) populations. We used the Multi-Ethnic Study of Atherosclerosis to examine association of QT with NOS1AP variants in an ethnically diverse cohort. METHODS: Twenty-eight tagging SNPs spanning NOS1AP were genotyped in 2847 MESA participants (approximately equal numbers of CAU, African Americans (AFA), Hispanics (HIS), and Chinese (CHN)), age 45-84 years, without cardiovascular disease. QT was measured using 12-lead ECG. Associations between QT and NOS1AP variants were evaluated using linear regression, adjusted for heart rate, age, gender, and field center stratified by ancestry, using an additive inheritance model. Ancestry informative markers (AIMs) and principal components using AIMs were used as additional covariates. RESULTS: More NOS1AP SNPs were associated with QT in CAU than the other races. In CAU, each copy of rs1932933 risk allele was associated with an increase in QT (4.9 msec, P = 7.20 x 10-7). Significant associations in CAU and HIS were located at the 5' end, while associations in CHN were located at the 3' end. CONCLUSIONS: NOS1AP variants were associated with QT in CAU, with weaker evidence for selected variants in HIS and CHN. Location of significant SNPs varied across ancestry. We identified possible novel associations at the 3' end of NOS1AP, where we observed significant association with QT in CHN only. Genotyping within these regions may determine functional variants affecting QT and SCD risk. In addition, investigations are needed across ethnically diverse population cohorts.
PMCID:3642094
PMID: 23347024
ISSN: 1542-474x
CID: 2747072
Genetic variation associated with circulating monocyte count in the eMERGE Network
With white blood cell count emerging as an important risk factor for chronic inflammatory diseases, genetic associations of differential leukocyte types, specifically monocyte count, are providing novel candidate genes and pathways to further investigate. Circulating monocytes play a critical role in vascular diseases such as in the formation of atherosclerotic plaque. We performed a joint and ancestry-stratified genome-wide association analyses to identify variants specifically associated with monocyte count in 11 014 subjects in the electronic Medical Records and Genomics Network. In the joint and European ancestry samples, we identified novel associations in the chromosome 16 interferon regulatory factor 8 (IRF8) gene (P-value = 2.78x10(-16), beta = -0.22). Other monocyte associations include novel missense variants in the chemokine-binding protein 2 (CCBP2) gene (P-value = 1.88x10(-7), beta = 0.30) and a region of replication found in ribophorin I (RPN1) (P-value = 2.63x10(-16), beta = -0.23) on chromosome 3. The CCBP2 and RPN1 region is located near GATA binding protein2 gene that has been previously shown to be associated with coronary heart disease. On chromosome 9, we found a novel association in the prostaglandin reductase 1 gene (P-value = 2.29x10(-7), beta = 0.16), which is downstream from lysophosphatidic acid receptor 1. This region has previously been shown to be associated with monocyte count. We also replicated monocyte associations of genome-wide significance (P-value = 5.68x10(-17), beta = -0.23) at the integrin, alpha 4 gene on chromosome 2. The novel IRF8 results and further replications provide supporting evidence of genetic regions associated with monocyte count.
PMCID:3633369
PMID: 23314186
ISSN: 1460-2083
CID: 2747082
Loci influencing blood pressure identified using a cardiovascular gene-centric array
Blood pressure (BP) is a heritable determinant of risk for cardiovascular disease (CVD). To investigate genetic associations with systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP) and pulse pressure (PP), we genotyped approximately 50 000 single-nucleotide polymorphisms (SNPs) that capture variation in approximately 2100 candidate genes for cardiovascular phenotypes in 61 619 individuals of European ancestry from cohort studies in the USA and Europe. We identified novel associations between rs347591 and SBP (chromosome 3p25.3, in an intron of HRH1) and between rs2169137 and DBP (chromosome1q32.1 in an intron of MDM4) and between rs2014408 and SBP (chromosome 11p15 in an intron of SOX6), previously reported to be associated with MAP. We also confirmed 10 previously known loci associated with SBP, DBP, MAP or PP (ADRB1, ATP2B1, SH2B3/ATXN2, CSK, CYP17A1, FURIN, HFE, LSP1, MTHFR, SOX6) at array-wide significance (P < 2.4 x 10(-6)). We then replicated these associations in an independent set of 65 886 individuals of European ancestry. The findings from expression QTL (eQTL) analysis showed associations of SNPs in the MDM4 region with MDM4 expression. We did not find any evidence of association of the two novel SNPs in MDM4 and HRH1 with sequelae of high BP including coronary artery disease (CAD), left ventricular hypertrophy (LVH) or stroke. In summary, we identified two novel loci associated with BP and confirmed multiple previously reported associations. Our findings extend our understanding of genes involved in BP regulation, some of which may eventually provide new targets for therapeutic intervention.
PMCID:3657476
PMID: 23303523
ISSN: 1460-2083
CID: 2747092
Effects of rare and common blood pressure gene variants on essential hypertension: results from the Family Blood Pressure Program, CLUE, and Atherosclerosis Risk in Communities studies
RATIONALE: Hypertension affects approximately 30% of adults in industrialized countries and is the major risk factor for cardiovascular disease. OBJECTIVE: We sought to study the genetic effect of coding and conserved noncoding variants in syndromic hypertension genes on systolic blood pressure (BP) and diastolic BP to assess their overall impact on essential hypertension. METHODS AND RESULTS: We resequenced 11 genes (AGT, CYP11B1, CYP17A1, HSD11B2, NR3C1, NR3C2, SCNN1A, SCNN1B, SCNN1G, WNK1, and WNK4) in 560 European American (EA) and African American ancestry GenNet participants with extreme systolic BP. We investigated genetic associations of 2535 variants with BP in 19997 EAs and in 6069 African Americans in 3 types of analyses. First, we studied the combined effects of all variants in GenNet. Second, we studied 1000 Genomes imputed polymorphic variants in 9747 EA and 3207 African American Atherosclerosis Risk in Communities subjects. Finally, we genotyped 37 missense and common noncoding variants in 6591 EAs and in 6521 individuals (3659 EA/2862 African American) from the CLUE and Family Blood Pressure Program studies, respectively. None of the variants individually reached significant false-discovery rates
PMCID:3548950
PMID: 23149595
ISSN: 1524-4571
CID: 2747102
Genetic relationship between five psychiatric disorders estimated from genome-wide SNPs
Most psychiatric disorders are moderately to highly heritable. The degree to which genetic variation is unique to individual disorders or shared across disorders is unclear. To examine shared genetic etiology, we use genome-wide genotype data from the Psychiatric Genomics Consortium (PGC) for cases and controls in schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD). We apply univariate and bivariate methods for the estimation of genetic variation within and covariation between disorders. SNPs explained 17-29% of the variance in liability. The genetic correlation calculated using common SNPs was high between schizophrenia and bipolar disorder (0.68 +/- 0.04 s.e.), moderate between schizophrenia and major depressive disorder (0.43 +/- 0.06 s.e.), bipolar disorder and major depressive disorder (0.47 +/- 0.06 s.e.), and ADHD and major depressive disorder (0.32 +/- 0.07 s.e.), low between schizophrenia and ASD (0.16 +/- 0.06 s.e.) and non-significant for other pairs of disorders as well as between psychiatric disorders and the negative control of Crohn's disease. This empirical evidence of shared genetic etiology for psychiatric disorders can inform nosology and encourages the investigation of common pathophysiologies for related disorders.
PMCID:3800159
PMID: 23933821
ISSN: 1061-4036
CID: 904052
An integrated map of genetic variation from 1,092 human genomes
By characterizing the geographic and functional spectrum of human genetic variation, the 1000 Genomes Project aims to build a resource to help to understand the genetic contribution to disease. Here we describe the genomes of 1,092 individuals from 14 populations, constructed using a combination of low-coverage whole-genome and exome sequencing. By developing methods to integrate information across several algorithms and diverse data sources, we provide a validated haplotype map of 38 million single nucleotide polymorphisms, 1.4 million short insertions and deletions, and more than 14,000 larger deletions. We show that individuals from different populations carry different profiles of rare and common variants, and that low-frequency variants show substantial geographic differentiation, which is further increased by the action of purifying selection. We show that evolutionary conservation and coding consequence are key determinants of the strength of purifying selection, that rare-variant load varies substantially across biological pathways, and that each individual contains hundreds of rare non-coding variants at conserved sites, such as motif-disrupting changes in transcription-factor-binding sites. This resource, which captures up to 98% of accessible single nucleotide polymorphisms at a frequency of 1% in related populations, enables analysis of common and low-frequency variants in individuals from diverse, including admixed, populations.
PMID: 23128226
ISSN: 1476-4687
CID: 3988632
The 1000 Genomes Project: data management and community access
The 1000 Genomes Project was launched as one of the largest distributed data collection and analysis projects ever undertaken in biology. In addition to the primary scientific goals of creating both a deep catalog of human genetic variation and extensive methods to accurately discover and characterize variation using new sequencing technologies, the project makes all of its data publicly available. Members of the project data coordination center have developed and deployed several tools to enable widespread data access.
PMCID:3340611
PMID: 22543379
ISSN: 1548-7105
CID: 3988622
Genetics and genomics in cardiovascular gene discovery
London ; Waltham, MA : Academic Press, 2012
pp. 231-259
ISBN: 0124158897
CID: 3987702
Genetic studies in isolated populations : Victor McKusick's contributions to population genetics
New York : Springer, 2012
pp. 107-117
ISBN: 1461416779
CID: 3985962
