@article {1288,
	title = {Enhanced statistical tests for GWAS in admixed populations: assessment using African Americans from CARe and a Breast Cancer Consortium.},
	journal = {PLoS Genet},
	volume = {7},
	year = {2011},
	month = {2011 Apr},
	pages = {e1001371},
	abstract = {<p>While genome-wide association studies (GWAS) have primarily examined populations of European ancestry, more recent studies often involve additional populations, including admixed populations such as African Americans and Latinos. In admixed populations, linkage disequilibrium (LD) exists both at a fine scale in ancestral populations and at a coarse scale (admixture-LD) due to chromosomal segments of distinct ancestry. Disease association statistics in admixed populations have previously considered SNP association (LD mapping) or admixture association (mapping by admixture-LD), but not both. Here, we introduce a new statistical framework for combining SNP and admixture association in case-control studies, as well as methods for local ancestry-aware imputation. We illustrate the gain in statistical power achieved by these methods by analyzing data of 6,209 unrelated African Americans from the CARe project genotyped on the Affymetrix 6.0 chip, in conjunction with both simulated and real phenotypes, as well as by analyzing the FGFR2 locus using breast cancer GWAS data from 5,761 African-American women. We show that, at typed SNPs, our method yields an 8\% increase in statistical power for finding disease risk loci compared to the power achieved by standard methods in case-control studies. At imputed SNPs, we observe an 11\% increase in statistical power for mapping disease loci when our local ancestry-aware imputation framework and the new scoring statistic are jointly employed. Finally, we show that our method increases statistical power in regions harboring the causal SNP in the case when the causal SNP is untyped and cannot be imputed. Our methods and our publicly available software are broadly applicable to GWAS in admixed populations.</p>},
	keywords = {African Americans, Algorithms, Breast Neoplasms, Chromosome Mapping, Coronary Disease, Diabetes Mellitus, Type 2, Female, Gene Frequency, Genetic Variation, Genetics, Population, Genome, Human, Genome-Wide Association Study, Genotype, Humans, Linkage Disequilibrium, Male, Odds Ratio, Phenotype, Polymorphism, Single Nucleotide, Principal Component Analysis, Receptor, Fibroblast Growth Factor, Type 2, Software},
	issn = {1553-7404},
	doi = {10.1371/journal.pgen.1001371},
	author = {Pasaniuc, Bogdan and Zaitlen, Noah and Lettre, Guillaume and Chen, Gary K and Tandon, Arti and Kao, W H Linda and Ruczinski, Ingo and Fornage, Myriam and Siscovick, David S and Zhu, Xiaofeng and Larkin, Emma and Lange, Leslie A and Cupples, L Adrienne and Yang, Qiong and Akylbekova, Ermeg L and Musani, Solomon K and Divers, Jasmin and Mychaleckyj, Joe and Li, Mingyao and Papanicolaou, George J and Millikan, Robert C and Ambrosone, Christine B and John, Esther M and Bernstein, Leslie and Zheng, Wei and Hu, Jennifer J and Ziegler, Regina G and Nyante, Sarah J and Bandera, Elisa V and Ingles, Sue A and Press, Michael F and Chanock, Stephen J and Deming, Sandra L and Rodriguez-Gil, Jorge L and Palmer, Cameron D and Buxbaum, Sarah and Ekunwe, Lynette and Hirschhorn, Joel N and Henderson, Brian E and Myers, Simon and Haiman, Christopher A and Reich, David and Patterson, Nick and Wilson, James G and Price, Alkes L}
}
@article {1305,
	title = {Genome-wide association study for serum urate concentrations and gout among African Americans identifies genomic risk loci and a novel URAT1 loss-of-function allele.},
	journal = {Hum Mol Genet},
	volume = {20},
	year = {2011},
	month = {2011 Oct 15},
	pages = {4056-68},
	abstract = {<p>Serum urate concentrations are highly heritable and elevated serum urate is a key risk factor for gout. Genome-wide association studies (GWAS) of serum urate in African American (AA) populations are lacking. We conducted a meta-analysis of GWAS of serum urate levels and gout among 5820 AA and a large candidate gene study among 6890 AA and 21 708 participants of European ancestry (EA) within the Candidate Gene Association Resource Consortium. Findings were tested for replication among 1996 independent AA individuals, and evaluated for their association among 28 283 EA participants of the CHARGE Consortium. Functional studies were conducted using (14)C-urate transport assays in mammalian Chinese hamster ovary cells. In the discovery GWAS of serum urate, three loci achieved genome-wide significance (P< 5.0 {\texttimes} 10(-8)): a novel locus near SGK1/SLC2A12 on chromosome 6 (rs9321453, P= 1.0 {\texttimes} 10(-9)), and two loci previously identified in EA participants, SLC2A9 (P= 3.8 {\texttimes} 10(-32)) and SLC22A12 (P= 2.1 {\texttimes} 10(-10)). A novel rare non-synonymous variant of large effect size in SLC22A12, rs12800450 (minor allele frequency 0.01, G65W), was identified and replicated (beta -1.19 mg/dl, P= 2.7 {\texttimes} 10(-16)). (14)C-urate transport assays showed reduced urate transport for the G65W URAT1 mutant. Finally, in analyses of 11 loci previously associated with serum urate in EA individuals, 10 of 11 lead single-nucleotide polymorphisms showed direction-consistent association with urate among AA. In summary, we identified and replicated one novel locus in association with serum urate levels and experimentally characterize the novel G65W variant in URAT1 as a functional allele. Our data support the importance of multi-ethnic GWAS in the identification of novel risk loci as well as functional variants.</p>},
	keywords = {Adult, African Americans, Aged, Animals, CHO Cells, Cricetinae, European Continental Ancestry Group, Female, Genetic Loci, Genetic Predisposition to Disease, Genome-Wide Association Study, Genotype, Gout, Humans, Loss of Heterozygosity, Male, Middle Aged, Organic Anion Transporters, Organic Cation Transport Proteins, Polymorphism, Single Nucleotide, Uric Acid, Young Adult},
	issn = {1460-2083},
	doi = {10.1093/hmg/ddr307},
	author = {Tin, Adrienne and Woodward, Owen M and Kao, Wen Hong Linda and Liu, Ching-Ti and Lu, Xiaoning and Nalls, Michael A and Shriner, Daniel and Semmo, Mariam and Akylbekova, Ermeg L and Wyatt, Sharon B and Hwang, Shih-Jen and Yang, Qiong and Zonderman, Alan B and Adeyemo, Adebowale A and Palmer, Cameron and Meng, Yan and Reilly, Muredach and Shlipak, Michael G and Siscovick, David and Evans, Michele K and Rotimi, Charles N and Flessner, Michael F and K{\"o}ttgen, Michael and Cupples, L Adrienne and Fox, Caroline S and K{\"o}ttgen, Anna}
}
