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1.  Genome-wide association analysis of red blood cell traits in African Americans: the COGENT Network 
Human Molecular Genetics  2013;22(12):2529-2538.
Laboratory red blood cell (RBC) measurements are clinically important, heritable and differ among ethnic groups. To identify genetic variants that contribute to RBC phenotypes in African Americans (AAs), we conducted a genome-wide association study in up to ∼16 500 AAs. The alpha-globin locus on chromosome 16pter [lead SNP rs13335629 in ITFG3 gene; P < 1E−13 for hemoglobin (Hgb), RBC count, mean corpuscular volume (MCV), MCH and MCHC] and the G6PD locus on Xq28 [lead SNP rs1050828; P < 1E − 13 for Hgb, hematocrit (Hct), MCV, RBC count and red cell distribution width (RDW)] were each associated with multiple RBC traits. At the alpha-globin region, both the common African 3.7 kb deletion and common single nucleotide polymorphisms (SNPs) appear to contribute independently to RBC phenotypes among AAs. In the 2p21 region, we identified a novel variant of PRKCE distinctly associated with Hct in AAs. In a genome-wide admixture mapping scan, local European ancestry at the 6p22 region containing HFE and LRRC16A was associated with higher Hgb. LRRC16A has been previously associated with the platelet count and mean platelet volume in AAs, but not with Hgb. Finally, we extended to AAs the findings of association of erythrocyte traits with several loci previously reported in Europeans and/or Asians, including CD164 and HBS1L-MYB. In summary, this large-scale genome-wide analysis in AAs has extended the importance of several RBC-associated genetic loci to AAs and identified allelic heterogeneity and pleiotropy at several previously known genetic loci associated with blood cell traits in AAs.
doi:10.1093/hmg/ddt087
PMCID: PMC3658166  PMID: 23446634
2.  An erythroid enhancer of BCL11A subject to genetic variation determines fetal hemoglobin level 
Science (New York, N.Y.)  2013;342(6155):253-257.
Genome-wide association studies (GWAS) have ascertained numerous trait-associated common genetic variants, frequently localized to regulatory DNA. We find that common genetic variation at BCL11A associated with fetal hemoglobin (HbF) level lies in noncoding sequences decorated by an erythroid enhancer chromatin signature. Fine-mapping uncovers a motif-disrupting common variant associated with reduced transcription factor binding, modestly diminished BCL11A expression and elevated HbF. The surrounding sequences function in vivo as a developmental stage-specific lineage-restricted enhancer. Genome engineering reveals the enhancer is required in erythroid but not B-lymphoid cells for BCL11A expression. These findings illustrate how GWAS may expose functional variants of modest impact within causal elements essential for appropriate gene expression. We propose the GWAS-marked BCL11A enhancer represents an attractive target for therapeutic genome engineering for the β-hemoglobinopathies.
doi:10.1126/science.1242088
PMCID: PMC4018826  PMID: 24115442
3.  Association of Variants at BCL11A and HBS1L-MYB with Hemoglobin F and Hospitalization Rates among Sickle Cell Patients in Cameroon 
PLoS ONE  2014;9(3):e92506.
Background
Genetic variation at loci influencing adult levels of HbF have been shown to modify the clinical course of sickle cell disease (SCD). Data on this important aspect of SCD have not yet been reported from West Africa. We investigated the relationship between HbF levels and the relevant genetic loci in 610 patients with SCD (98% HbSS homozygotes) from Cameroon, and compared the results to a well-characterized African-American cohort.
Methods and Findings
Socio-demographic and clinical features were collected and medical records reviewed. Only patients >5 years old, who had not received a blood transfusion or treatment with hydroxyurea were included. Hemoglobin electrophoresis and a full blood count were conducted upon arrival at the hospital. RFLP-PCR was used to describe the HBB gene haplotypes. SNaPshot PCR, Capillary electrophoresis and cycle sequencing were used for the genotyping of 10 selected SNPs. Genetic analysis was performed with PLINK software and statistical models in the statistical package R. Allele frequencies of relevant variants at BCL11A were similar to those detected in African Americans; although the relationships with Hb F were significant (p <.001), they explained substantially less of the variance in HbF than was observed among African Americans (∼ 2% vs 10%). SNPs in HBS1L-MYB region (HMIP) likewise had a significant impact on HbF, however, we did not find an association between HbF and the variations in HBB cluster and OR51B5/6 locus on chromosome 11p, due in part to the virtual absence of the Senegal and Indian Arab haplotypes. We also found evidence that selected SNPs in HBS1L-MYB region (HMIP) and BCL11A affect both other hematological indices and rates of hospitalization.
Conclusions
This study has confirmed the associations of SNPs in BCL11A and HBS1L-MYB and fetal haemoglobin in Cameroonian SCA patients; hematological indices and hospitalization rates were also associated with specific allelic variants.
doi:10.1371/journal.pone.0092506
PMCID: PMC3965431  PMID: 24667352
4.  Lessons and Implications from Genome-Wide Association Studies (GWAS) Findings of Blood Cell Phenotypes 
Genes  2014;5(1):51-64.
Genome-wide association studies (GWAS) have identified reproducible genetic associations with hundreds of human diseases and traits. The vast majority of these associated single nucleotide polymorphisms (SNPs) are non-coding, highlighting the challenge in moving from genetic findings to mechanistic and functional insights. Nevertheless, large-scale (epi)genomic studies and bioinformatic analyses strongly suggest that GWAS hits are not randomly distributed in the genome but rather pinpoint specific biological pathways important for disease development or phenotypic variation. In this review, we focus on GWAS discoveries for the three main blood cell types: red blood cells, white blood cells and platelets. We summarize the knowledge gained from GWAS of these phenotypes and discuss their possible clinical implications for common (e.g., anemia) and rare (e.g., myeloproliferative neoplasms) human blood-related diseases. Finally, we argue that blood phenotypes are ideal to study the genetics of complex human traits because they are fully amenable to experimental testing.
doi:10.3390/genes5010051
PMCID: PMC3978511  PMID: 24705286
GWAS; hemoglobin; hematocrit; red blood cell; erythrocyte; white blood cell; leukocyte; platelet; human genetics
5.  A Meta-Analysis Identifies New Loci Associated with Body Mass index in Individuals of African Ancestry 
Monda, Keri L. | Chen, Gary K. | Taylor, Kira C. | Palmer, Cameron | Edwards, Todd L. | Lange, Leslie A. | Ng, Maggie C.Y. | Adeyemo, Adebowale A. | Allison, Matthew A. | Bielak, Lawrence F. | Chen, Guanji | Graff, Mariaelisa | Irvin, Marguerite R. | Rhie, Suhn K. | Li, Guo | Liu, Yongmei | Liu, Youfang | Lu, Yingchang | Nalls, Michael A. | Sun, Yan V. | Wojczynski, Mary K. | Yanek, Lisa R. | Aldrich, Melinda C. | Ademola, Adeyinka | Amos, Christopher I. | Bandera, Elisa V. | Bock, Cathryn H. | Britton, Angela | Broeckel, Ulrich | Cai, Quiyin | Caporaso, Neil E. | Carlson, Chris | Carpten, John | Casey, Graham | Chen, Wei-Min | Chen, Fang | Chen, Yii-Der I. | Chiang, Charleston W.K. | Coetzee, Gerhard A. | Demerath, Ellen | Deming-Halverson, Sandra L. | Driver, Ryan W. | Dubbert, Patricia | Feitosa, Mary F. | Freedman, Barry I. | Gillanders, Elizabeth M. | Gottesman, Omri | Guo, Xiuqing | Haritunians, Talin | Harris, Tamara | Harris, Curtis C. | Hennis, Anselm JM | Hernandez, Dena G. | McNeill, Lorna H. | Howard, Timothy D. | Howard, Barbara V. | Howard, Virginia J. | Johnson, Karen C. | Kang, Sun J. | Keating, Brendan J. | Kolb, Suzanne | Kuller, Lewis H. | Kutlar, Abdullah | Langefeld, Carl D. | Lettre, Guillaume | Lohman, Kurt | Lotay, Vaneet | Lyon, Helen | Manson, JoAnn E. | Maixner, William | Meng, Yan A. | Monroe, Kristine R. | Morhason-Bello, Imran | Murphy, Adam B. | Mychaleckyj, Josyf C. | Nadukuru, Rajiv | Nathanson, Katherine L. | Nayak, Uma | N’Diaye, Amidou | Nemesure, Barbara | Wu, Suh-Yuh | Leske, M. Cristina | Neslund-Dudas, Christine | Neuhouser, Marian | Nyante, Sarah | Ochs-Balcom, Heather | Ogunniyi, Adesola | Ogundiran, Temidayo O. | Ojengbede, Oladosu | Olopade, Olufunmilayo I. | Palmer, Julie R. | Ruiz-Narvaez, Edward A. | Palmer, Nicholette D. | Press, Michael F. | Rampersaud, Evandine | Rasmussen-Torvik, Laura J. | Rodriguez-Gil, Jorge L. | Salako, Babatunde | Schadt, Eric E. | Schwartz, Ann G. | Shriner, Daniel A. | Siscovick, David | Smith, Shad B. | Wassertheil-Smoller, Sylvia | Speliotes, Elizabeth K. | Spitz, Margaret R. | Sucheston, Lara | Taylor, Herman | Tayo, Bamidele O. | Tucker, Margaret A. | Van Den Berg, David J. | Velez Edwards, Digna R. | Wang, Zhaoming | Wiencke, John K. | Winkler, Thomas W. | Witte, John S. | Wrensch, Margaret | Wu, Xifeng | Yang, James J. | Levin, Albert M. | Young, Taylor R. | Zakai, Neil A. | Cushman, Mary | Zanetti, Krista A. | Zhao, Jing Hua | Zhao, Wei | Zheng, Yonglan | Zhou, Jie | Ziegler, Regina G. | Zmuda, Joseph M. | Fernandes, Jyotika K. | Gilkeson, Gary S. | Kamen, Diane L. | Hunt, Kelly J. | Spruill, Ida J. | Ambrosone, Christine B. | Ambs, Stefan | Arnett, Donna K. | Atwood, Larry | Becker, Diane M. | Berndt, Sonja I. | Bernstein, Leslie | Blot, William J. | Borecki, Ingrid B. | Bottinger, Erwin P. | Bowden, Donald W. | Burke, Gregory | Chanock, Stephen J. | Cooper, Richard S. | Ding, Jingzhong | Duggan, David | Evans, Michele K. | Fox, Caroline | Garvey, W. Timothy | Bradfield, Jonathan P. | Hakonarson, Hakon | Grant, Struan F.A. | Hsing, Ann | Chu, Lisa | Hu, Jennifer J. | Huo, Dezheng | Ingles, Sue A. | John, Esther M. | Jordan, Joanne M. | Kabagambe, Edmond K. | Kardia, Sharon L.R. | Kittles, Rick A. | Goodman, Phyllis J. | Klein, Eric A. | Kolonel, Laurence N. | Le Marchand, Loic | Liu, Simin | McKnight, Barbara | Millikan, Robert C. | Mosley, Thomas H. | Padhukasahasram, Badri | Williams, L. Keoki | Patel, Sanjay R. | Peters, Ulrike | Pettaway, Curtis A. | Peyser, Patricia A. | Psaty, Bruce M. | Redline, Susan | Rotimi, Charles N. | Rybicki, Benjamin A. | Sale, Michèle M. | Schreiner, Pamela J. | Signorello, Lisa B. | Singleton, Andrew B. | Stanford, Janet L. | Strom, Sara S. | Thun, Michael J. | Vitolins, Mara | Zheng, Wei | Moore, Jason H. | Williams, Scott M. | Zhu, Xiaofeng | Zonderman, Alan B. | Kooperberg, Charles | Papanicolaou, George | Henderson, Brian E. | Reiner, Alex P. | Hirschhorn, Joel N. | Loos, Ruth JF | North, Kari E. | Haiman, Christopher A.
Nature genetics  2013;45(6):690-696.
Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry, and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one novel locus at 5q33 (GALNT10, rs7708584, p=3.4×10−11) and another at 7p15 when combined with data from the Giant consortium (MIR148A/NFE2L3, rs10261878, p=1.2×10−10). We also found suggestive evidence of an association at a third locus at 6q16 in the African ancestry sample (KLHL32, rs974417, p=6.9×10−8). Thirty-two of the 36 previously established BMI variants displayed directionally consistent effect estimates in our GWAS (binomial p=9.7×10−7), of which five reached genome-wide significance. These findings provide strong support for shared BMI loci across populations as well as for the utility of studying ancestrally diverse populations.
doi:10.1038/ng.2608
PMCID: PMC3694490  PMID: 23583978
6.  Deep Resequencing of GWAS Loci Identifies Rare Variants in CARD9, IL23R and RNF186 That Are Associated with Ulcerative Colitis 
PLoS Genetics  2013;9(9):e1003723.
Genome-wide association studies and follow-up meta-analyses in Crohn's disease (CD) and ulcerative colitis (UC) have recently identified 163 disease-associated loci that meet genome-wide significance for these two inflammatory bowel diseases (IBD). These discoveries have already had a tremendous impact on our understanding of the genetic architecture of these diseases and have directed functional studies that have revealed some of the biological functions that are important to IBD (e.g. autophagy). Nonetheless, these loci can only explain a small proportion of disease variance (∼14% in CD and 7.5% in UC), suggesting that not only are additional loci to be found but that the known loci may contain high effect rare risk variants that have gone undetected by GWAS. To test this, we have used a targeted sequencing approach in 200 UC cases and 150 healthy controls (HC), all of French Canadian descent, to study 55 genes in regions associated with UC. We performed follow-up genotyping of 42 rare non-synonymous variants in independent case-control cohorts (totaling 14,435 UC cases and 20,204 HC). Our results confirmed significant association to rare non-synonymous coding variants in both IL23R and CARD9, previously identified from sequencing of CD loci, as well as identified a novel association in RNF186. With the exception of CARD9 (OR = 0.39), the rare non-synonymous variants identified were of moderate effect (OR = 1.49 for RNF186 and OR = 0.79 for IL23R). RNF186 encodes a protein with a RING domain having predicted E3 ubiquitin-protein ligase activity and two transmembrane domains. Importantly, the disease-coding variant is located in the ubiquitin ligase domain. Finally, our results suggest that rare variants in genes identified by genome-wide association in UC are unlikely to contribute significantly to the overall variance for the disease. Rather, these are expected to help focus functional studies of the corresponding disease loci.
Author Summary
Genetic studies of common diseases have seen tremendous progress in the last half-decade primarily due to recent technologies that enable a systematic examination of genetic markers across the entire genome in large numbers of patients and healthy controls. The studies, while identifying genomic regions that influence a person's risk for developing disease, often do not pinpoint the actual gene or gene variants that account for this risk (called a causal gene/variant). A prime example of this can be seen with the 163 genetic risk factors that have recently been associated with the chronic inflammatory bowel diseases known as Crohn's disease and ulcerative colitis. For less than a handful of these 163 is the causative change in the genetic code known. The current study used an approach to directly look at the genetic code for a subset of these and identified a causative change in the genetic code for eight risk factors for ulcerative colitis. This finding is particularly important because it directs biological studies to understand the mechanisms that lead to this chronic life-long inflammatory disease.
doi:10.1371/journal.pgen.1003723
PMCID: PMC3772057  PMID: 24068945
7.  Fine-mapping at three loci known to affect fetal hemoglobin levels explains additional genetic variation 
Nature genetics  2010;42(12):1049-1051.
We used resequencing and genotyping in African Americans with sickle cell anemia (SCA) to characterize associations with fetal hemoglobin (HbF) levels at the BCL11A, HBS1L-MYB and β-globin loci. Fine-mapping of HbF association signals at these loci confirmed seven SNPs with independent effects and increased the explained heritable variation in HbF levels from 38.6% to 49.5%. We also identified rare missense variants that causally implicate MYB in HbF production.
doi:10.1038/ng.707
PMCID: PMC3740938  PMID: 21057501
8.  FTO genotype is associated with phenotypic variability of body mass index 
Yang, Jian | Loos, Ruth J. F. | Powell, Joseph E. | Medland, Sarah E. | Speliotes, Elizabeth K. | Chasman, Daniel I. | Rose, Lynda M. | Thorleifsson, Gudmar | Steinthorsdottir, Valgerdur | Mägi, Reedik | Waite, Lindsay | Smith, Albert Vernon | Yerges-Armstrong, Laura M. | Monda, Keri L. | Hadley, David | Mahajan, Anubha | Li, Guo | Kapur, Karen | Vitart, Veronique | Huffman, Jennifer E. | Wang, Sophie R. | Palmer, Cameron | Esko, Tõnu | Fischer, Krista | Zhao, Jing Hua | Demirkan, Ayşe | Isaacs, Aaron | Feitosa, Mary F. | Luan, Jian’an | Heard-Costa, Nancy L. | White, Charles | Jackson, Anne U. | Preuss, Michael | Ziegler, Andreas | Eriksson, Joel | Kutalik, Zoltán | Frau, Francesca | Nolte, Ilja M. | Van Vliet-Ostaptchouk, Jana V. | Hottenga, Jouke-Jan | Jacobs, Kevin B. | Verweij, Niek | Goel, Anuj | Medina-Gomez, Carolina | Estrada, Karol | Bragg-Gresham, Jennifer Lynn | Sanna, Serena | Sidore, Carlo | Tyrer, Jonathan | Teumer, Alexander | Prokopenko, Inga | Mangino, Massimo | Lindgren, Cecilia M. | Assimes, Themistocles L. | Shuldiner, Alan R. | Hui, Jennie | Beilby, John P. | McArdle, Wendy L. | Hall, Per | Haritunians, Talin | Zgaga, Lina | Kolcic, Ivana | Polasek, Ozren | Zemunik, Tatijana | Oostra, Ben A. | Junttila, M. Juhani | Grönberg, Henrik | Schreiber, Stefan | Peters, Annette | Hicks, Andrew A. | Stephens, Jonathan | Foad, Nicola S. | Laitinen, Jaana | Pouta, Anneli | Kaakinen, Marika | Willemsen, Gonneke | Vink, Jacqueline M. | Wild, Sarah H. | Navis, Gerjan | Asselbergs, Folkert W. | Homuth, Georg | John, Ulrich | Iribarren, Carlos | Harris, Tamara | Launer, Lenore | Gudnason, Vilmundur | O’Connell, Jeffrey R. | Boerwinkle, Eric | Cadby, Gemma | Palmer, Lyle J. | James, Alan L. | Musk, Arthur W. | Ingelsson, Erik | Psaty, Bruce M. | Beckmann, Jacques S. | Waeber, Gerard | Vollenweider, Peter | Hayward, Caroline | Wright, Alan F. | Rudan, Igor | Groop, Leif C. | Metspalu, Andres | Khaw, Kay Tee | van Duijn, Cornelia M. | Borecki, Ingrid B. | Province, Michael A. | Wareham, Nicholas J. | Tardif, Jean-Claude | Huikuri, Heikki V. | Cupples, L. Adrienne | Atwood, Larry D. | Fox, Caroline S. | Boehnke, Michael | Collins, Francis S. | Mohlke, Karen L. | Erdmann, Jeanette | Schunkert, Heribert | Hengstenberg, Christian | Stark, Klaus | Lorentzon, Mattias | Ohlsson, Claes | Cusi, Daniele | Staessen, Jan A. | Van der Klauw, Melanie M. | Pramstaller, Peter P. | Kathiresan, Sekar | Jolley, Jennifer D. | Ripatti, Samuli | Jarvelin, Marjo-Riitta | de Geus, Eco J. C. | Boomsma, Dorret I. | Penninx, Brenda | Wilson, James F. | Campbell, Harry | Chanock, Stephen J. | van der Harst, Pim | Hamsten, Anders | Watkins, Hugh | Hofman, Albert | Witteman, Jacqueline C. | Zillikens, M. Carola | Uitterlinden, André G. | Rivadeneira, Fernando | Zillikens, M. Carola | Kiemeney, Lambertus A. | Vermeulen, Sita H. | Abecasis, Goncalo R. | Schlessinger, David | Schipf, Sabine | Stumvoll, Michael | Tönjes, Anke | Spector, Tim D. | North, Kari E. | Lettre, Guillaume | McCarthy, Mark I. | Berndt, Sonja I. | Heath, Andrew C. | Madden, Pamela A. F. | Nyholt, Dale R. | Montgomery, Grant W. | Martin, Nicholas G. | McKnight, Barbara | Strachan, David P. | Hill, William G. | Snieder, Harold | Ridker, Paul M. | Thorsteinsdottir, Unnur | Stefansson, Kari | Frayling, Timothy M. | Hirschhorn, Joel N. | Goddard, Michael E. | Visscher, Peter M.
Nature  2012;490(7419):267-272.
There is evidence across several species for genetic control of phenotypic variation of complex traits1–4, such that the variance among phenotypes is genotype dependent. Understanding genetic control of variability is important in evolutionary biology, agricultural selection programmes and human medicine, yet for complex traits, no individual genetic variants associated with variance, as opposed to the mean, have been identified. Here we perform a meta-analysis of genome-wide association studies of phenotypic variation using 170,000 samples on height and body mass index (BMI) in human populations. We report evidence that the single nucleotide polymorphism (SNP) rs7202116 at the FTO gene locus, which is known to be associated with obesity (as measured by mean BMI for each rs7202116 genotype)5–7, is also associated with phenotypic variability. We show that the results are not due to scale effects or other artefacts, and find no other experiment-wise significant evidence for effects on variability, either at loci other than FTO for BMI or at any locus for height. The difference in variance for BMI among individuals with opposite homozygous genotypes at the FTO locus is approximately 7%, corresponding to a difference of 0.5 kilograms in the standard deviation of weight. Our results indicate that genetic variants can be discovered that are associated with variability, and that between-person variability in obesity can partly be explained by the genotype at the FTO locus. The results are consistent with reported FTO by environment interactions for BMI8, possibly mediated by DNA methylation9,10. Our BMI results for other SNPs and our height results for all SNPs suggest that most genetic variants, including those that influence mean height or mean BMI, are not associated with phenotypic variance, or that their effects on variability are too small to detect even with samples sizes greater than 100,000.
doi:10.1038/nature11401
PMCID: PMC3564953  PMID: 22982992
9.  Genetic association analysis highlights new loci that modulate hematological trait variation in Caucasians and African Americans 
Human genetics  2010;129(3):307-317.
Red blood cell, white blood cell, and platelet measures, including their count, sub-type and volume, are important diagnostic and prognostic clinical parameters for several human diseases. To identify novel loci associated with hematological traits, and compare the architecture of these phenotypes between ethnic groups, the CARe Project genotyped 49,094 single nucleotide polymorphisms (SNPs) that capture variation in ~2,100 candidate genes in DNA of 23,439 Caucasians and 7,112 African Americans from five population-based cohorts. We found strong novel associations between erythrocyte phenotypes and the glucose-6 phosphate dehydrogenase (G6PD) A-allele in African Americans (rs1050828, P < 2.0 × 10−13, T-allele associated with lower red blood cell count, hemoglobin, and hematocrit, and higher mean corpuscular volume), and between platelet count and a SNP at the tropomyosin-4 (TPM4) locus (rs8109288, P = 3.0 × 10−7 in Caucasians; P = 3.0 × 10−7 in African Americans, T-allele associated with lower platelet count). We strongly replicated many genetic associations to blood cell phenotypes previously established in Caucasians. A common variant of the α-globin (HBA2-HBA1) locus was associated with red blood cell traits in African Americans, but not in Caucasians (rs1211375, P < 7 × 10−8, A-allele associated with lower hemoglobin, mean corpuscular hemoglobin, and mean corpuscular volume). Our results show similarities but also differences in the genetic regulation of hematological traits in European- and African-derived populations, and highlight the role of natural selection in shaping these differences.
doi:10.1007/s00439-010-0925-1
PMCID: PMC3442357  PMID: 21153663
10.  Genomic inflation factors under polygenic inheritance 
Population structure, including population stratification and cryptic relatedness, can cause spurious associations in genome-wide association studies (GWAS). Usually, the scaled median or mean test statistic for association calculated from multiple single-nucleotide-polymorphisms across the genome is used to assess such effects, and ‘genomic control' can be applied subsequently to adjust test statistics at individual loci by a genomic inflation factor. Published GWAS have clearly shown that there are many loci underlying genetic variation for a wide range of complex diseases and traits, implying that a substantial proportion of the genome should show inflation of the test statistic. Here, we show by theory, simulation and analysis of data that in the absence of population structure and other technical artefacts, but in the presence of polygenic inheritance, substantial genomic inflation is expected. Its magnitude depends on sample size, heritability, linkage disequilibrium structure and the number of causal variants. Our predictions are consistent with empirical observations on height in independent samples of ∼4000 and ∼133 000 individuals.
doi:10.1038/ejhg.2011.39
PMCID: PMC3137506  PMID: 21407268
genome-wide association study; genomic inflation factor; polygenic inheritance
11.  Deep resequencing of GWAS loci identifies independent rare variants associated with inflammatory bowel disease 
Nature Genetics  2011;43(11):1066-1073.
More than a thousand disease susceptibility loci have been identified via genome-wide association studies (GWAS) of common variants; however, the specific genes and full allelic spectrum of causal variants underlying these findings generally remain to be defined. We utilize pooled next-generation sequencing to study 56 genes in regions associated to Crohn’s Disease in 350 cases and 350 controls. Follow up genotyping of 70 rare and low-frequency protein-altering variants (MAF ~ .001-.05) in nine independent case-control series (16054 CD patients, 12153 UC patients, 17575 healthy controls) identifies four additional independent risk factors in NOD2, two additional protective variants in IL23R, a highly significant association to a novel, protective splice variant in CARD9 (p < 1e-16, OR ~ 0.29), as well as additional associations to coding variants in IL18RAP, CUL2, C1orf106, PTPN22 and MUC19. We extend the results of successful GWAS by providing novel, rare, and likely functional variants that will empower functional experiments and predictive models.
doi:10.1038/ng.952
PMCID: PMC3378381  PMID: 21983784
12.  Multi-Ethnic Analysis of Lipid-Associated Loci: The NHLBI CARe Project 
PLoS ONE  2012;7(5):e36473.
Background
Whereas it is well established that plasma lipid levels have substantial heritability within populations, it remains unclear how many of the genetic determinants reported in previous studies (largely performed in European American cohorts) are relevant in different ethnicities.
Methodology/Principal Findings
We tested a set of ∼50,000 polymorphisms from ∼2,000 candidate genes and genetic loci from genome-wide association studies (GWAS) for association with low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) in 25,000 European Americans and 9,000 African Americans in the National Heart, Lung, and Blood Institute (NHLBI) Candidate Gene Association Resource (CARe). We replicated associations for a number of genes in one or both ethnicities and identified a novel lipid-associated variant in a locus harboring ICAM1. We compared the architecture of genetic loci associated with lipids in both African Americans and European Americans and found that the same genes were relevant across ethnic groups but the specific associated variants at each gene often differed.
Conclusions/Significance
We identify or provide further evidence for a number of genetic determinants of plasma lipid levels through population association studies. In many loci the determinants appear to differ substantially between African Americans and European Americans.
doi:10.1371/journal.pone.0036473
PMCID: PMC3357427  PMID: 22629316
13.  A Meta-Analysis and Genome-Wide Association Study of Platelet Count and Mean Platelet Volume in African Americans 
PLoS Genetics  2012;8(3):e1002491.
Several genetic variants associated with platelet count and mean platelet volume (MPV) were recently reported in people of European ancestry. In this meta-analysis of 7 genome-wide association studies (GWAS) enrolling African Americans, our aim was to identify novel genetic variants associated with platelet count and MPV. For all cohorts, GWAS analysis was performed using additive models after adjusting for age, sex, and population stratification. For both platelet phenotypes, meta-analyses were conducted using inverse-variance weighted fixed-effect models. Platelet aggregation assays in whole blood were performed in the participants of the GeneSTAR cohort. Genetic variants in ten independent regions were associated with platelet count (N = 16,388) with p<5×10−8 of which 5 have not been associated with platelet count in previous GWAS. The novel genetic variants associated with platelet count were in the following regions (the most significant SNP, closest gene, and p-value): 6p22 (rs12526480, LRRC16A, p = 9.1×10−9), 7q11 (rs13236689, CD36, p = 2.8×10−9), 10q21 (rs7896518, JMJD1C, p = 2.3×10−12), 11q13 (rs477895, BAD, p = 4.9×10−8), and 20q13 (rs151361, SLMO2, p = 9.4×10−9). Three of these loci (10q21, 11q13, and 20q13) were replicated in European Americans (N = 14,909) and one (11q13) in Hispanic Americans (N = 3,462). For MPV (N = 4,531), genetic variants in 3 regions were significant at p<5×10−8, two of which were also associated with platelet count. Previously reported regions that were also significant in this study were 6p21, 6q23, 7q22, 12q24, and 19p13 for platelet count and 7q22, 17q11, and 19p13 for MPV. The most significant SNP in 1 region was also associated with ADP-induced maximal platelet aggregation in whole blood (12q24). Thus through a meta-analysis of GWAS enrolling African Americans, we have identified 5 novel regions associated with platelet count of which 3 were replicated in other ethnic groups. In addition, we also found one region associated with platelet aggregation that may play a potential role in atherothrombosis.
Author Summary
The majority of the variation in platelet count and mean platelet volume between individuals is heritable. We performed genome-wide association studies in more than 16,000 African American participants from seven population-based cohorts to identify genetic variants that correlate with variation in platelet count and mean platelet volume. We observed statistically significant evidence (p-value<5×10−8) that 10 genomic regions were associated with platelet count and 3 were associated with mean platelet volume. Of the regions that were significantly associated, we found 5 novel regions that were not reported previously in other populations. Three of these 5 regions were also associated with platelet count in European Americans and Hispanic Americans. All these regions contain genes that are either known to have or potentially may have a role in determining platelet count and/or mean platelet volume. We further found that one of these regions was also associated with agonist-induced platelet aggregation. Further studies will determine the exact role played by these genomic regions in platelet biology. The knowledge generated by this and other studies will not only help us better understand platelet biology but can also lead us to the discovery of new anti-platelet drugs.
doi:10.1371/journal.pgen.1002491
PMCID: PMC3299192  PMID: 22423221
14.  Correction: Identification, Replication, and Fine-Mapping of Loci Associated with Adult Height in Individuals of African Ancestry 
N'Diaye, Amidou | Chen, Gary K. | Palmer, Cameron D. | Ge, Bing | Tayo, Bamidele | Mathias, Rasika A. | Ding, Jingzhong | Nalls, Michael A. | Adeyemo, Adebowale | Adoue, Véronique | Ambrosone, Christine B. | Atwood, Larry | Bandera, Elisa V. | Becker, Lewis C. | Berndt, Sonja I. | Bernstein, Leslie | Blot, William J. | Boerwinkle, Eric | Britton, Angela | Casey, Graham | Chanock, Stephen J. | Demerath, Ellen | Deming, Sandra L. | Diver, W. Ryan | Fox, Caroline | Harris, Tamara B. | Hernandez, Dena G. | Hu, Jennifer J. | Ingles, Sue A. | John, Esther M. | Johnson, Craig | Keating, Brendan | Kittles, Rick A. | Kolonel, Laurence N. | Kritchevsky, Stephen B. | Le Marchand, Loic | Lohman, Kurt | Liu, Jiankang | Millikan, Robert C. | Murphy, Adam | Musani, Solomon | Neslund-Dudas, Christine | North, Kari E. | Nyante, Sarah | Ogunniyi, Adesola | Ostrander, Elaine A. | Papanicolaou, George | Patel, Sanjay | Pettaway, Curtis A. | Press, Michael F. | Redline, Susan | Rodriguez-Gil, Jorge L. | Rotimi, Charles | Rybicki, Benjamin A. | Salako, Babatunde | Schreiner, Pamela J. | Signorello, Lisa B. | Singleton, Andrew B. | Stanford, Janet L. | Stram, Alex H. | Stram, Daniel O. | Strom, Sara S. | Suktitipat, Bhoom | Thun, Michael J. | Witte, John S. | Yanek, Lisa R. | Ziegler, Regina G. | Zheng, Wei | Zhu, Xiaofeng | Zmuda, Joseph M. | Zonderman, Alan B. | Evans, Michele K. | Liu, Yongmei | Becker, Diane M. | Cooper, Richard S. | Pastinen, Tomi | Henderson, Brian E. | Hirschhorn, Joel N. | Lettre, Guillaume | Haiman, Christopher A.
PLoS Genetics  2011;7(11):10.1371/annotation/58c67154-3f10-4155-9085-dcd6e3689008.
doi:10.1371/annotation/58c67154-3f10-4155-9085-dcd6e3689008
PMCID: PMC3227698
15.  European Ancestry as a Risk Factor for Atrial Fibrillation in African Americans 
Circulation  2010;122(20):2009-2015.
Background
Despite a higher burden of standard atrial fibrillation (AF) risk factors, African Americans have a lower risk of AF than whites. It is unknown if the higher riskis due to genetic or environmental factors. As African Americans have varying degrees of European ancestry, we sought to test the hypothesis that European ancestry is an independent risk factor for AF.
Methods and Results
We studied whites (n=4,543) and African Americans (n=822) in the Cardiovascular Health Study (CHS) and whites (n=10,902) and Africa Americans (n=3,517) in the Atherosclerosis Risk in Communities (ARIC) Study (n=3,517). Percent European ancestry in African Americans was estimated using 1,747 ancestry informative markers (AIMs) from the Illumina custom ITMAT-Broad-CARe (IBC) array. Among African Americans without baseline AF, 120 of 804 CHS participants and 181 of 3,517 ARIC participants developed incident AF. A meta-analysis from the two studies revealed that every 10% increase in European ancestry increased the risk of AF by 13% (HR 1.13, 95% CI 1.03–1.23, p=0.007). After adjusting for potential confounders, European ancestry remained a predictor of incident AF in each cohort alone, with a combined estimated hazard ratio for each 10% increase in European ancestry of 1.17 (95% CI 1.07–1.29, p=0.001). A second analysis using 3,192 AIMs from a genome wide Affymetrix 6.0 array in ARIC African Americans yielded similar results.
Conclusion
European ancestry predicted risk of incident AF. Our study suggests that investigating genetic variants contributing to differential AF risk in individuals of African versus European ancestry will be informative.
doi:10.1161/CIRCULATIONAHA.110.958306
PMCID: PMC3058884  PMID: 21098467
Atrial Fibrillation Genetics; Ancestry; African Americans
16.  Association of linear growth impairment in pediatric Crohn's disease and a known height locus: a pilot study 
Annals of human genetics  2010;74(6):489-497.
SUMMARY
The etiology of growth impairment in Crohn's disease (CD) has been inadequately explained by nutritional, hormonal, and/or disease-related factors, suggesting that genetics may be an additional contributor. The aim of this cross-sectional study was to investigate genetic variants associated with linear growth in pediatric-onset CD.
We genotyped 951 subjects (317 CD patient-parent trios) for sixty-four polymorphisms within 14 CD-susceptibility and 23 stature-associated loci. Patient height-for-age Z-score < -1.64 was used to dichotomize probands into growth-impaired and nongrowth-impaired groups. The transmission disequilibrium test (TDT) was used to study association to growth impairment. There was a significant association between growth impairment in CD (height-for-age Z-score < -1.64) and a stature-related polymorphism in the dymeclin gene DYM (rs8099594) (OR=3.2, CI [1.57-6.51], p=0.0007). In addition, there was nominal over-transmission of two CD-susceptibility alleles, 10q21.1 intergenic region (rs10761659) and ATG16L1 (rs10210302), in growth-impaired CD children (OR=2.36, CI [1.26-4.41] p=0.0056 and OR=2.45, CI [1.22-4.95] p=0.0094, respectively).
Our data indicate that genetic influences due to stature-associated and possibly CD risk alleles may predispose CD patients to alterations in linear growth. This is the first report of a link between a stature-associated locus and growth impairment in CD.
doi:10.1111/j.1469-1809.2010.00606.x
PMCID: PMC2955808  PMID: 20846217
height; growth retardation; inflammatory bowel disease; DYM; dymeclin
17.  Identification, Replication, and Fine-Mapping of Loci Associated with Adult Height in Individuals of African Ancestry 
N'Diaye, Amidou | Chen, Gary K. | Palmer, Cameron D. | Ge, Bing | Tayo, Bamidele | Mathias, Rasika A. | Ding, Jingzhong | Nalls, Michael A. | Adeyemo, Adebowale | Adoue, Véronique | Ambrosone, Christine B. | Atwood, Larry | Bandera, Elisa V. | Becker, Lewis C. | Berndt, Sonja I. | Bernstein, Leslie | Blot, William J. | Boerwinkle, Eric | Britton, Angela | Casey, Graham | Chanock, Stephen J. | Demerath, Ellen | Deming, Sandra L. | Diver, W. Ryan | Fox, Caroline | Harris, Tamara B. | Hernandez, Dena G. | Hu, Jennifer J. | Ingles, Sue A. | John, Esther M. | Johnson, Craig | Keating, Brendan | Kittles, Rick A. | Kolonel, Laurence N. | Kritchevsky, Stephen B. | Le Marchand, Loic | Lohman, Kurt | Liu, Jiankang | Millikan, Robert C. | Murphy, Adam | Musani, Solomon | Neslund-Dudas, Christine | North, Kari E. | Nyante, Sarah | Ogunniyi, Adesola | Ostrander, Elaine A. | Papanicolaou, George | Patel, Sanjay | Pettaway, Curtis A. | Press, Michael F. | Redline, Susan | Rodriguez-Gil, Jorge L. | Rotimi, Charles | Rybicki, Benjamin A. | Salako, Babatunde | Schreiner, Pamela J. | Signorello, Lisa B. | Singleton, Andrew B. | Stanford, Janet L. | Stram, Alex H. | Stram, Daniel O. | Strom, Sara S. | Suktitipat, Bhoom | Thun, Michael J. | Witte, John S. | Yanek, Lisa R. | Ziegler, Regina G. | Zheng, Wei | Zhu, Xiaofeng | Zmuda, Joseph M. | Zonderman, Alan B. | Evans, Michele K. | Liu, Yongmei | Becker, Diane M. | Cooper, Richard S. | Pastinen, Tomi | Henderson, Brian E. | Hirschhorn, Joel N. | Lettre, Guillaume | Haiman, Christopher A.
PLoS Genetics  2011;7(10):e1002298.
Adult height is a classic polygenic trait of high heritability (h2 ∼0.8). More than 180 single nucleotide polymorphisms (SNPs), identified mostly in populations of European descent, are associated with height. These variants convey modest effects and explain ∼10% of the variance in height. Discovery efforts in other populations, while limited, have revealed loci for height not previously implicated in individuals of European ancestry. Here, we performed a meta-analysis of genome-wide association (GWA) results for adult height in 20,427 individuals of African ancestry with replication in up to 16,436 African Americans. We found two novel height loci (Xp22-rs12393627, P = 3.4×10−12 and 2p14-rs4315565, P = 1.2×10−8). As a group, height associations discovered in European-ancestry samples replicate in individuals of African ancestry (P = 1.7×10−4 for overall replication). Fine-mapping of the European height loci in African-ancestry individuals showed an enrichment of SNPs that are associated with expression of nearby genes when compared to the index European height SNPs (P<0.01). Our results highlight the utility of genetic studies in non-European populations to understand the etiology of complex human diseases and traits.
Author Summary
Adult height is an ideal phenotype to improve our understanding of the genetic architecture of complex diseases and traits: it is easily measured and usually available in large cohorts, relatively stable, and mostly influenced by genetics (narrow-sense heritability of height h2∼0.8). Genome-wide association (GWA) studies in individuals of European ancestry have identified >180 single nucleotide polymorphisms (SNPs) associated with height. In the current study, we continued to use height as a model polygenic trait and explored the genetic influence in populations of African ancestry through a meta-analysis of GWA height results from 20,809 individuals of African descent. We identified two novel height loci not previously found in Europeans. We also replicated the European height signals, suggesting that many of the genetic variants that are associated with height are shared between individuals of European and African descent. Finally, in fine-mapping the European height loci in African-ancestry individuals, we found SNPs more likely to be associated with the expression of nearby genes than the SNPs originally found in Europeans. Thus, our results support the utility of performing genetic studies in non-European populations to gain insights into complex human diseases and traits.
doi:10.1371/journal.pgen.1002298
PMCID: PMC3188544  PMID: 21998595
18.  Large-scale association analyses identifies 13 new susceptibility loci for coronary artery disease 
Schunkert, Heribert | König, Inke R. | Kathiresan, Sekar | Reilly, Muredach P. | Assimes, Themistocles L. | Holm, Hilma | Preuss, Michael | Stewart, Alexandre F. R. | Barbalic, Maja | Gieger, Christian | Absher, Devin | Aherrahrou, Zouhair | Allayee, Hooman | Altshuler, David | Anand, Sonia S. | Andersen, Karl | Anderson, Jeffrey L. | Ardissino, Diego | Ball, Stephen G. | Balmforth, Anthony J. | Barnes, Timothy A. | Becker, Diane M. | Becker, Lewis C. | Berger, Klaus | Bis, Joshua C. | Boekholdt, S. Matthijs | Boerwinkle, Eric | Braund, Peter S. | Brown, Morris J. | Burnett, Mary Susan | Buysschaert, Ian | Carlquist, Cardiogenics, John F. | Chen, Li | Cichon, Sven | Codd, Veryan | Davies, Robert W. | Dedoussis, George | Dehghan, Abbas | Demissie, Serkalem | Devaney, Joseph M. | Do, Ron | Doering, Angela | Eifert, Sandra | El Mokhtari, Nour Eddine | Ellis, Stephen G. | Elosua, Roberto | Engert, James C. | Epstein, Stephen E. | Faire, Ulf de | Fischer, Marcus | Folsom, Aaron R. | Freyer, Jennifer | Gigante, Bruna | Girelli, Domenico | Gretarsdottir, Solveig | Gudnason, Vilmundur | Gulcher, Jeffrey R. | Halperin, Eran | Hammond, Naomi | Hazen, Stanley L. | Hofman, Albert | Horne, Benjamin D. | Illig, Thomas | Iribarren, Carlos | Jones, Gregory T. | Jukema, J.Wouter | Kaiser, Michael A. | Kaplan, Lee M. | Kastelein, John J.P. | Khaw, Kay-Tee | Knowles, Joshua W. | Kolovou, Genovefa | Kong, Augustine | Laaksonen, Reijo | Lambrechts, Diether | Leander, Karin | Lettre, Guillaume | Li, Mingyao | Lieb, Wolfgang | Linsel-Nitschke, Patrick | Loley, Christina | Lotery, Andrew J. | Mannucci, Pier M. | Maouche, Seraya | Martinelli, Nicola | McKeown, Pascal P. | Meisinger, Christa | Meitinger, Thomas | Melander, Olle | Merlini, Pier Angelica | Mooser, Vincent | Morgan, Thomas | Mühleisen, Thomas W. | Muhlestein, Joseph B. | Münzel, Thomas | Musunuru, Kiran | Nahrstaedt, Janja | Nelson, Christopher P. | Nöthen, Markus M. | Olivieri, Oliviero | Patel, Riyaz S. | Patterson, Chris C. | Peters, Annette | Peyvandi, Flora | Qu, Liming | Quyyumi, Arshed A. | Rader, Daniel J. | Rallidis, Loukianos S. | Rice, Catherine | Rosendaal, Frits R. | Rubin, Diana | Salomaa, Veikko | Sampietro, M. Lourdes | Sandhu, Manj S. | Schadt, Eric | Schäfer, Arne | Schillert, Arne | Schreiber, Stefan | Schrezenmeir, Jürgen | Schwartz, Stephen M. | Siscovick, David S. | Sivananthan, Mohan | Sivapalaratnam, Suthesh | Smith, Albert | Smith, Tamara B. | Snoep, Jaapjan D. | Soranzo, Nicole | Spertus, John A. | Stark, Klaus | Stirrups, Kathy | Stoll, Monika | Tang, W. H. Wilson | Tennstedt, Stephanie | Thorgeirsson, Gudmundur | Thorleifsson, Gudmar | Tomaszewski, Maciej | Uitterlinden, Andre G. | van Rij, Andre M. | Voight, Benjamin F. | Wareham, Nick J. | Wells, George A. | Wichmann, H.-Erich | Wild, Philipp S. | Willenborg, Christina | Witteman, Jaqueline C. M. | Wright, Benjamin J. | Ye, Shu | Zeller, Tanja | Ziegler, Andreas | Cambien, Francois | Goodall, Alison H. | Cupples, L. Adrienne | Quertermous, Thomas | März, Winfried | Hengstenberg, Christian | Blankenberg, Stefan | Ouwehand, Willem H. | Hall, Alistair S. | Deloukas, Panos | Thompson, John R. | Stefansson, Kari | Roberts, Robert | Thorsteinsdottir, Unnur | O’Donnell, Christopher J. | McPherson, Ruth | Erdmann, Jeanette | Samani, Nilesh J.
Nature genetics  2011;43(4):333-338.
We performed a meta-analysis of 14 genome-wide association studies of coronary artery disease (CAD) comprising 22,233 cases and 64,762 controls of European descent, followed by genotyping of top association signals in 60,738 additional individuals. This genomic analysis identified 13 novel loci harboring one or more SNPs that were associated with CAD at P<5×10−8 and confirmed the association of 10 of 12 previously reported CAD loci. The 13 novel loci displayed risk allele frequencies ranging from 0.13 to 0.91 and were associated with a 6 to 17 percent increase in the risk of CAD per allele. Notably, only three of the novel loci displayed significant association with traditional CAD risk factors, while the majority lie in gene regions not previously implicated in the pathogenesis of CAD. Finally, five of the novel CAD risk loci appear to have pleiotropic effects, showing strong association with various other human diseases or traits.
doi:10.1038/ng.784
PMCID: PMC3119261  PMID: 21378990
19.  Fine mapping of the association with obesity at the FTO locus in African-derived populations 
Human Molecular Genetics  2010;19(14):2907-2916.
Genome-wide association studies have identified many common genetic variants that are associated with polygenic traits, and have typically been performed with individuals of recent European ancestry. In these populations, many common variants are tightly correlated, with the perfect or near-perfect proxies for the functional or true variant showing equivalent evidence of association, considerably limiting the resolution of fine mapping. Populations with recent African ancestry often have less extensive and/or different patterns of linkage disequilibrium (LD), and have been proposed to be useful in fine-mapping studies. Here, we strongly replicate and fine map in populations of predominantly African ancestry the association between variation at the FTO locus and body mass index (BMI) that is well established in populations of European ancestry. We genotyped single nucleotide polymorphisms that are correlated with the signal of association in individuals of European ancestry but that have varying degrees of correlation in African-derived individuals. Most of the variants, including one previously proposed as functionally important, have no significant association with BMI, but two variants, rs3751812 and rs9941349, show strong evidence of association (P = 2.58 × 10−6 and 3.61 × 10−6 in a meta-analysis of 9881 individuals). Thus, we have both strongly replicated this association in African-ancestry populations and narrowed the list of potentially causal variants to those that are correlated with rs3751812 and rs9941349 in African-derived populations. This study illustrates the potential of using populations with different LD patterns to fine map associations and helps pave the way for genetically guided functional studies at the FTO locus.
doi:10.1093/hmg/ddq178
PMCID: PMC2893809  PMID: 20430937
20.  Genome-wide association of anthropometric traits in African- and African-derived populations 
Human Molecular Genetics  2010;19(13):2725-2738.
Genome-wide association (GWA) studies have identified common variants that are associated with a variety of traits and diseases, but most studies have been performed in European-derived populations. Here, we describe the first genome-wide analyses of imputed genotype and copy number variants (CNVs) for anthropometric measures in African-derived populations: 1188 Nigerians from Igbo-Ora and Ibadan, Nigeria, and 743 African-Americans from Maywood, IL. To improve the reach of our study, we used imputation to estimate genotypes at ∼2.1 million single-nucleotide polymorphisms (SNPs) and also tested CNVs for association. No SNPs or common CNVs reached a genome-wide significance level for association with height or body mass index (BMI), and the best signals from a meta-analysis of the two cohorts did not replicate in ∼3700 African-Americans and Jamaicans. However, several loci previously confirmed in European populations showed evidence of replication in our GWA panel of African-derived populations, including variants near IHH and DLEU7 for height and MC4R for BMI. Analysis of global burden of rare CNVs suggested that lean individuals possess greater total burden of CNVs, but this finding was not supported in an independent European population. Our results suggest that there are not multiple loci with strong effects on anthropometric traits in African-derived populations and that sample sizes comparable to those needed in European GWA studies will be required to identify replicable associations. Meta-analysis of this data set with additional studies in African-ancestry populations will be helpful to improve power to detect novel associations.
doi:10.1093/hmg/ddq154
PMCID: PMC2883343  PMID: 20400458
21.  Genome-Wide Association Study of White Blood Cell Count in 16,388 African Americans: the Continental Origins and Genetic Epidemiology Network (COGENT) 
PLoS Genetics  2011;7(6):e1002108.
Total white blood cell (WBC) and neutrophil counts are lower among individuals of African descent due to the common African-derived “null” variant of the Duffy Antigen Receptor for Chemokines (DARC) gene. Additional common genetic polymorphisms were recently associated with total WBC and WBC sub-type levels in European and Japanese populations. No additional loci that account for WBC variability have been identified in African Americans. In order to address this, we performed a large genome-wide association study (GWAS) of total WBC and cell subtype counts in 16,388 African-American participants from 7 population-based cohorts available in the Continental Origins and Genetic Epidemiology Network. In addition to the DARC locus on chromosome 1q23, we identified two other regions (chromosomes 4q13 and 16q22) associated with WBC in African Americans (P<2.5×10−8). The lead SNP (rs9131) on chromosome 4q13 is located in the CXCL2 gene, which encodes a chemotactic cytokine for polymorphonuclear leukocytes. Independent evidence of the novel CXCL2 association with WBC was present in 3,551 Hispanic Americans, 14,767 Japanese, and 19,509 European Americans. The index SNP (rs12149261) on chromosome 16q22 associated with WBC count is located in a large inter-chromosomal segmental duplication encompassing part of the hydrocephalus inducing homolog (HYDIN) gene. We demonstrate that the chromosome 16q22 association finding is most likely due to a genotyping artifact as a consequence of sequence similarity between duplicated regions on chromosomes 16q22 and 1q21. Among the WBC loci recently identified in European or Japanese populations, replication was observed in our African-American meta-analysis for rs445 of CDK6 on chromosome 7q21 and rs4065321 of PSMD3-CSF3 region on chromosome 17q21. In summary, the CXCL2, CDK6, and PSMD3-CSF3 regions are associated with WBC count in African American and other populations. We also demonstrate that large inter-chromosomal duplications can result in false positive associations in GWAS.
Author Summary
Although recent genome-wide association studies have identified common genetic variants associated with total white blood cell (WBC) and WBC sub-type counts in European and Japanese ancestry populations, whether these or other loci account for differences in WBC count among African Americans is unknown. By examining >16,000 African Americans, we show that, in addition to the previously identified Duffy Antigen Receptor for Chemokines (DARC) locus on chromosome 1, another variant, rs9131, and other nearby variants on human chromosome 4 are associated with total WBC count in African Americans. The variants span the CXCL2 gene, which encodes an inflammatory mediator involved in WBC production and migration. We show that the association is not restricted to African Americans but is also present in independent samples of European Americans, Hispanic Americans, and Japanese. This finding is potentially important because WBC mediate or have altered counts in a variety of acute and chronic disorders.
doi:10.1371/journal.pgen.1002108
PMCID: PMC3128101  PMID: 21738479
22.  Multiple Loci Are Associated with White Blood Cell Phenotypes 
Nalls, Michael A. | Couper, David J. | Tanaka, Toshiko | van Rooij, Frank J. A. | Chen, Ming-Huei | Smith, Albert V. | Toniolo, Daniela | Zakai, Neil A. | Yang, Qiong | Greinacher, Andreas | Wood, Andrew R. | Garcia, Melissa | Gasparini, Paolo | Liu, Yongmei | Lumley, Thomas | Folsom, Aaron R. | Reiner, Alex P. | Gieger, Christian | Lagou, Vasiliki | Felix, Janine F. | Völzke, Henry | Gouskova, Natalia A. | Biffi, Alessandro | Döring, Angela | Völker, Uwe | Chong, Sean | Wiggins, Kerri L. | Rendon, Augusto | Dehghan, Abbas | Moore, Matt | Taylor, Kent | Wilson, James G. | Lettre, Guillaume | Hofman, Albert | Bis, Joshua C. | Pirastu, Nicola | Fox, Caroline S. | Meisinger, Christa | Sambrook, Jennifer | Arepalli, Sampath | Nauck, Matthias | Prokisch, Holger | Stephens, Jonathan | Glazer, Nicole L. | Cupples, L. Adrienne | Okada, Yukinori | Takahashi, Atsushi | Kamatani, Yoichiro | Matsuda, Koichi | Tsunoda, Tatsuhiko | Tanaka, Toshihiro | Kubo, Michiaki | Nakamura, Yusuke | Yamamoto, Kazuhiko | Kamatani, Naoyuki | Stumvoll, Michael | Tönjes, Anke | Prokopenko, Inga | Illig, Thomas | Patel, Kushang V. | Garner, Stephen F. | Kuhnel, Brigitte | Mangino, Massimo | Oostra, Ben A. | Thein, Swee Lay | Coresh, Josef | Wichmann, H.-Erich | Menzel, Stephan | Lin, JingPing | Pistis, Giorgio | Uitterlinden, André G. | Spector, Tim D. | Teumer, Alexander | Eiriksdottir, Gudny | Gudnason, Vilmundur | Bandinelli, Stefania | Frayling, Timothy M. | Chakravarti, Aravinda | van Duijn, Cornelia M. | Melzer, David | Ouwehand, Willem H. | Levy, Daniel | Boerwinkle, Eric | Singleton, Andrew B. | Hernandez, Dena G. | Longo, Dan L. | Soranzo, Nicole | Witteman, Jacqueline C. M. | Psaty, Bruce M. | Ferrucci, Luigi | Harris, Tamara B. | O'Donnell, Christopher J. | Ganesh, Santhi K.
PLoS Genetics  2011;7(6):e1002113.
White blood cell (WBC) count is a common clinical measure from complete blood count assays, and it varies widely among healthy individuals. Total WBC count and its constituent subtypes have been shown to be moderately heritable, with the heritability estimates varying across cell types. We studied 19,509 subjects from seven cohorts in a discovery analysis, and 11,823 subjects from ten cohorts for replication analyses, to determine genetic factors influencing variability within the normal hematological range for total WBC count and five WBC subtype measures. Cohort specific data was supplied by the CHARGE, HeamGen, and INGI consortia, as well as independent collaborative studies. We identified and replicated ten associations with total WBC count and five WBC subtypes at seven different genomic loci (total WBC count—6p21 in the HLA region, 17q21 near ORMDL3, and CSF3; neutrophil count—17q21; basophil count- 3p21 near RPN1 and C3orf27; lymphocyte count—6p21, 19p13 at EPS15L1; monocyte count—2q31 at ITGA4, 3q21, 8q24 an intergenic region, 9q31 near EDG2), including three previously reported associations and seven novel associations. To investigate functional relationships among variants contributing to variability in the six WBC traits, we utilized gene expression- and pathways-based analyses. We implemented gene-clustering algorithms to evaluate functional connectivity among implicated loci and showed functional relationships across cell types. Gene expression data from whole blood was utilized to show that significant biological consequences can be extracted from our genome-wide analyses, with effect estimates for significant loci from the meta-analyses being highly corellated with the proximal gene expression. In addition, collaborative efforts between the groups contributing to this study and related studies conducted by the COGENT and RIKEN groups allowed for the examination of effect homogeneity for genome-wide significant associations across populations of diverse ancestral backgrounds.
Author Summary
WBC traits are highly variable, moderately heritable, and commonly assayed as part of clinical complete blood count (CBC) examinations. The counts of constituent cell subtypes comprising the WBC count measure are assayed as part of a standard clinical WBC differential test. In this study we employed meta-analytic techniques and identified ten associations with WBC measures at seven genomic loci in a large sample set of over 31,000 participants. Cohort specific data was supplied by the CHARGE, HeamGen, and INGI consortia, as well as independent collaborative studies. We confirm previous associations of WBC traits with three loci and identified seven novel loci. We also utilize a number of additional analytic methods to infer the functional relatedness of independently implicated loci across WBC phenotypes, as well as investigate direct functional consequences of these loci through analyses of genomic variation affecting the expression of proximal genes in samples of whole blood. In addition, subsequent collaborative efforts with studies of WBC traits in African-American and Japanese cohorts allowed for the investigation of the effects of these genomic variants across populations of diverse continental ancestries.
doi:10.1371/journal.pgen.1002113
PMCID: PMC3128114  PMID: 21738480
23.  Candidate Gene Association Resource (CARe): Design, Methods, and Proof of Concept 
Background
. The National Heart, Lung, and Blood Institute’s Candidate Gene Association Resource (CARe), a planned cross-cohort analysis of genetic variation in cardiovascular, pulmonary, hematological, and sleep-related traits, comprises more than 40,000 participants representing four ethnic groups in nine community-based cohorts. The goals of CARe include the discovery of new variants associated with traits using a candidate gene approach and the discovery of new variants using the genome-wide association mapping approach specifically in African Americans.
Methods and Results
. CARe has assembled DNA samples for more than 40,000 individuals self-identified as European-American, African-American, Hispanic, or Chinese-American, with accompanying data on hundreds of phenotypes that have been standardized and deposited in the CARe Phenotype Database. All participants were genotyped for seven single-nucleotide polymorphisms (SNPs) selected based on prior association evidence. We performed association analyses relating each of these SNPs to lipid traits, stratified by gender and ethnicity and adjusted for age and age2. In at least two of the ethnic groups, SNPs near CETP, LIPC, and LPL strongly replicated for association with high-density lipoprotein cholesterol concentrations, PCSK9 with low-density lipoprotein cholesterol levels, and LPL and APOA5 with serum triglycerides. Notably, some SNPs showed varying effect sizes and significance of association in different ethnic groups.
Conclusions
. The CARe Pilot Study validates the operational framework for phenotype collection, SNP genotyping, and analytical pipeline of the CARe project and validates the planned candidate gene study of ~2,000 biologic candidate loci in all participants and genome-wide association study in ~8,000 African-American participants. CARe will serve as a valuable resource for the scientific community.
doi:10.1161/CIRCGENETICS.109.882696
PMCID: PMC3048024  PMID: 20400780
Genetics; lipids; diabetes; blood pressure; epidemiology
24.  A common variant of HMGA2 is associated with adult and childhood height in the general population 
Nature genetics  2007;39(10):1245-1250.
Human height is a classic, highly heritable quantitative trait. To begin to identify genetic variants influencing height, we examined genome-wide association data from 4,921 individuals. Common variants in the HMGA2 oncogene, exemplified by rs1042725, were associated with height (P = 4 × 10−8). HMGA2 is also a strong biological candidate for height, as rare, severe mutations in this gene alter body size in mice and humans, so we tested rs1042725 in additional samples. We confirmed the association in 19,064 adults from four further studies (P = 3 × 10−11, overall P = 4 × 10−16, including the genome-wide association data). We also observed the association in children (P = 1 × 10−6, N = 6,827) and a tall/short case-control study (P = 4 × 10−6, N = 3,207). We estimate that rs1042725 explains ~0.3% of population variation in height (~0.4 cm increased adult height per C allele). There are few examples of common genetic variants reproducibly associated with human quantitative traits; these results represent, to our knowledge, the first consistently replicated association with adult and childhood height.
doi:10.1038/ng2121
PMCID: PMC3086278  PMID: 17767157
25.  Meta-analysis identifies 13 new loci associated with waist-hip ratio and reveals sexual dimorphism in the genetic basis of fat distribution 
Heid, Iris M. | Jackson, Anne U. | Randall, Joshua C. | Winkler, Thomas W. | Qi, Lu | Steinthorsdottir, Valgerdur | Thorleifsson, Gudmar | Zillikens, M. Carola | Speliotes, Elizabeth K. | Mägi, Reedik | Workalemahu, Tsegaselassie | White, Charles C. | Bouatia-Naji, Nabila | Harris, Tamara B. | Berndt, Sonja I. | Ingelsson, Erik | Willer, Cristen J. | Weedon, Michael N. | Luan, Jian'an | Vedantam, Sailaja | Esko, Tõnu | Kilpeläinen, Tuomas O. | Kutalik, Zoltán | Li, Shengxu | Monda, Keri L. | Dixon, Anna L. | Holmes, Christopher C. | Kaplan, Lee M. | Liang, Liming | Min, Josine L. | Moffatt, Miriam F. | Molony, Cliona | Nicholson, George | Schadt, Eric E. | Zondervan, Krina T. | Feitosa, Mary F. | Ferreira, Teresa | Allen, Hana Lango | Weyant, Robert J. | Wheeler, Eleanor | Wood, Andrew R. | Estrada, Karol | Goddard, Michael E. | Lettre, Guillaume | Mangino, Massimo | Nyholt, Dale R. | Purcell, Shaun | Vernon Smith, Albert | Visscher, Peter M. | Yang, Jian | McCaroll, Steven A. | Nemesh, James | Voight, Benjamin F. | Absher, Devin | Amin, Najaf | Aspelund, Thor | Coin, Lachlan | Glazer, Nicole L. | Hayward, Caroline | Heard-Costa, Nancy L. | Hottenga, Jouke-Jan | Johansson, Åsa | Johnson, Toby | Kaakinen, Marika | Kapur, Karen | Ketkar, Shamika | Knowles, Joshua W. | Kraft, Peter | Kraja, Aldi T. | Lamina, Claudia | Leitzmann, Michael F. | McKnight, Barbara | Morris, Andrew P. | Ong, Ken K. | Perry, John R.B. | Peters, Marjolein J. | Polasek, Ozren | Prokopenko, Inga | Rayner, Nigel W. | Ripatti, Samuli | Rivadeneira, Fernando | Robertson, Neil R. | Sanna, Serena | Sovio, Ulla | Surakka, Ida | Teumer, Alexander | van Wingerden, Sophie | Vitart, Veronique | Zhao, Jing Hua | Cavalcanti-Proença, Christine | Chines, Peter S. | Fisher, Eva | Kulzer, Jennifer R. | Lecoeur, Cecile | Narisu, Narisu | Sandholt, Camilla | Scott, Laura J. | Silander, Kaisa | Stark, Klaus | Tammesoo, Mari-Liis | Teslovich, Tanya M. | John Timpson, Nicholas | Watanabe, Richard M. | Welch, Ryan | Chasman, Daniel I. | Cooper, Matthew N. | Jansson, John-Olov | Kettunen, Johannes | Lawrence, Robert W. | Pellikka, Niina | Perola, Markus | Vandenput, Liesbeth | Alavere, Helene | Almgren, Peter | Atwood, Larry D. | Bennett, Amanda J. | Biffar, Reiner | Bonnycastle, Lori L. | Bornstein, Stefan R. | Buchanan, Thomas A. | Campbell, Harry | Day, Ian N.M. | Dei, Mariano | Dörr, Marcus | Elliott, Paul | Erdos, Michael R. | Eriksson, Johan G. | Freimer, Nelson B. | Fu, Mao | Gaget, Stefan | Geus, Eco J.C. | Gjesing, Anette P. | Grallert, Harald | Gräßler, Jürgen | Groves, Christopher J. | Guiducci, Candace | Hartikainen, Anna-Liisa | Hassanali, Neelam | Havulinna, Aki S. | Herzig, Karl-Heinz | Hicks, Andrew A. | Hui, Jennie | Igl, Wilmar | Jousilahti, Pekka | Jula, Antti | Kajantie, Eero | Kinnunen, Leena | Kolcic, Ivana | Koskinen, Seppo | Kovacs, Peter | Kroemer, Heyo K. | Krzelj, Vjekoslav | Kuusisto, Johanna | Kvaloy, Kirsti | Laitinen, Jaana | Lantieri, Olivier | Lathrop, G. Mark | Lokki, Marja-Liisa | Luben, Robert N. | Ludwig, Barbara | McArdle, Wendy L. | McCarthy, Anne | Morken, Mario A. | Nelis, Mari | Neville, Matt J. | Paré, Guillaume | Parker, Alex N. | Peden, John F. | Pichler, Irene | Pietiläinen, Kirsi H. | Platou, Carl G.P. | Pouta, Anneli | Ridderstråle, Martin | Samani, Nilesh J. | Saramies, Jouko | Sinisalo, Juha | Smit, Jan H. | Strawbridge, Rona J. | Stringham, Heather M. | Swift, Amy J. | Teder-Laving, Maris | Thomson, Brian | Usala, Gianluca | van Meurs, Joyce B.J. | van Ommen, Gert-Jan | Vatin, Vincent | Volpato, Claudia B. | Wallaschofski, Henri | Walters, G. Bragi | Widen, Elisabeth | Wild, Sarah H. | Willemsen, Gonneke | Witte, Daniel R. | Zgaga, Lina | Zitting, Paavo | Beilby, John P. | James, Alan L. | Kähönen, Mika | Lehtimäki, Terho | Nieminen, Markku S. | Ohlsson, Claes | Palmer, Lyle J. | Raitakari, Olli | Ridker, Paul M. | Stumvoll, Michael | Tönjes, Anke | Viikari, Jorma | Balkau, Beverley | Ben-Shlomo, Yoav | Bergman, Richard N. | Boeing, Heiner | Smith, George Davey | Ebrahim, Shah | Froguel, Philippe | Hansen, Torben | Hengstenberg, Christian | Hveem, Kristian | Isomaa, Bo | Jørgensen, Torben | Karpe, Fredrik | Khaw, Kay-Tee | Laakso, Markku | Lawlor, Debbie A. | Marre, Michel | Meitinger, Thomas | Metspalu, Andres | Midthjell, Kristian | Pedersen, Oluf | Salomaa, Veikko | Schwarz, Peter E.H. | Tuomi, Tiinamaija | Tuomilehto, Jaakko | Valle, Timo T. | Wareham, Nicholas J. | Arnold, Alice M. | Beckmann, Jacques S. | Bergmann, Sven | Boerwinkle, Eric | Boomsma, Dorret I. | Caulfield, Mark J. | Collins, Francis S. | Eiriksdottir, Gudny | Gudnason, Vilmundur | Gyllensten, Ulf | Hamsten, Anders | Hattersley, Andrew T. | Hofman, Albert | Hu, Frank B. | Illig, Thomas | Iribarren, Carlos | Jarvelin, Marjo-Riitta | Kao, W.H. Linda | Kaprio, Jaakko | Launer, Lenore J. | Munroe, Patricia B. | Oostra, Ben | Penninx, Brenda W. | Pramstaller, Peter P. | Psaty, Bruce M. | Quertermous, Thomas | Rissanen, Aila | Rudan, Igor | Shuldiner, Alan R. | Soranzo, Nicole | Spector, Timothy D. | Syvanen, Ann-Christine | Uda, Manuela | Uitterlinden, André | Völzke, Henry | Vollenweider, Peter | Wilson, James F. | Witteman, Jacqueline C. | Wright, Alan F. | Abecasis, Gonçalo R. | Boehnke, Michael | Borecki, Ingrid B. | Deloukas, Panos | Frayling, Timothy M. | Groop, Leif C. | Haritunians, Talin | Hunter, David J. | Kaplan, Robert C. | North, Kari E. | O'Connell, Jeffrey R. | Peltonen, Leena | Schlessinger, David | Strachan, David P. | Hirschhorn, Joel N. | Assimes, Themistocles L. | Wichmann, H.-Erich | Thorsteinsdottir, Unnur | van Duijn, Cornelia M. | Stefansson, Kari | Cupples, L. Adrienne | Loos, Ruth J.F. | Barroso, Inês | McCarthy, Mark I. | Fox, Caroline S. | Mohlke, Karen L. | Lindgren, Cecilia M.
Nature genetics  2010;42(11):949-960.
Waist-hip ratio (WHR) is a measure of body fat distribution and a predictor of metabolic consequences independent of overall adiposity. WHR is heritable, but few genetic variants influencing this trait have been identified. We conducted a meta-analysis of 32 genome-wide association studies for WHR adjusted for body-mass-index (up to 77,167 participants), following up 16 loci in an additional 29 studies (up to 113,636 subjects). We identified 13 novel loci in or near RSPO3, VEGFA, TBX15-WARS2, NFE2L3, GRB14, DNM3-PIGC, ITPR2-SSPN, LY86, HOXC13, ADAMTS9, ZNRF3-KREMEN1, NISCH-STAB1, and CPEB4 (P 1.9 × 10−9 to 1.8 × 10−40), and the known signal at LYPLAL1. Seven of these loci exhibited marked sexual dimorphism, all with a stronger effect on WHR in women than men (P for sex-difference 1.9 × 10−3 to 1.2 × 10−13). These findings provide evidence for multiple loci that modulate body fat distribution, independent of overall adiposity, and reveal powerful gene-by-sex interactions.
doi:10.1038/ng.685
PMCID: PMC3000924  PMID: 20935629
genome-wide association; waist-hip-ratio; body fat distribution; central obesity; meta-analysis; genetics; visceral adipose tissue; metabolism; body composition; Expression Quantitative Trait Loci; sex difference

Results 1-25 (36)