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Trans-ethnic fine-mapping of lipid loci identifies population-specific signals and allelic heterogeneity that increases the trait variance explained
Journal article   Open access   Peer reviewed

Trans-ethnic fine-mapping of lipid loci identifies population-specific signals and allelic heterogeneity that increases the trait variance explained

Ying Wu, Lindsay L Waite, Anne U Jackson, Wayne H-H Sheu, Steven Buyske, Devin Absher, Donna K Arnett, Eric Boerwinkle, Lori L Bonnycastle, Cara L Carty, …
PLoS genetics, Vol.9(3), e1003379
03/2013
DOI: 10.1371/journal.pgen.1003379
PMCID: PMC3605054
PMID: 23555291
url
https://doi.org/10.1371/journal.pgen.1003379View
Published (Version of record) Open Access

Abstract

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 × 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.
Apolipoprotein A-V European Continental Ancestry Group - genetics Genome-Wide Association Study Apolipoproteins A - genetics Lipoproteins, HDL - genetics Lipoproteins, HDL - blood Humans African Americans - genetics Cholesterol, HDL - genetics Lipoproteins, LDL - genetics Proprotein Convertases - genetics Cholesterol, LDL - genetics Serine Endopeptidases - genetics Triglycerides - blood Cholesterol, HDL - blood Cholesterol, LDL - blood Triglycerides - genetics Lipoproteins, LDL - blood Proprotein Convertase 9

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