title: Variance component model to account for sample structure in genome-wide association studies.
abstract: Although genome-wide association studies (GWASs) have identified numerous loci associated with complex traits, imprecise modeling of the genetic relatedness within study samples may cause substantial inflation of test statistics and possibly spurious associations. Variance component approaches, such as efficient mixed-model association (EMMA), can correct for a wide range of sample structures by explicitly accounting for pairwise relatedness between individuals, using high-density markers to model the phenotype distribution; but such approaches are computationally impractical. We report here a variance component approach implemented in publicly available software, EMMA eXpedited (EMMAX), that reduces the computational time for analyzing large GWAS data sets from years to hours. We apply this method to two human GWAS data sets, performing association analysis for ten quantitative traits from the Northern Finland Birth Cohort and seven common diseases from the Wellcome Trust Case Control Consortium. We find that EMMAX outperforms both principal component analysis and genomic control in correcting for sample structure.
authors.affiliation: Center for Statistical Genetics, Department of Biostatistics, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Hyun Min
authors.initials: HM
authors.lastname: Kang
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Sul
authors.forename: Susan K
authors.initials: SK
authors.lastname: Service
authors.forename: Noah A
authors.initials: NA
authors.lastname: Zaitlen
authors.forename: Sit-Yee
authors.initials: SY
authors.lastname: Kong
authors.forename: Nelson B
authors.initials: NB
authors.lastname: Freimer
authors.forename: Chiara
authors.initials: C
authors.lastname: Sabatti
authors.forename: Eleazar
authors.initials: E
authors.lastname: Eskin
mesh_terms: D055106:Genome-Wide Association Study; D006801:Humans; D008957:Models, Genetic; D015233:Models, Statistical; D020641:Polymorphism, Single Nucleotide; D044382:Population Groups / Q000235:genetics*; D025341:Principal Component Analysis; D040641:Quantitative Trait Loci; D012984:Software