title: Meta-analysis of genome-wide association studies of attention-deficit/hyperactivity disorder.
abstract: OBJECTIVE
  Although twin and family studies have shown attention-deficit/hyperactivity disorder (ADHD) to be highly heritable, genetic variants influencing the trait at a genome-wide significant level have yet to be identified. As prior genome-wide association studies (GWAS) have not yielded significant results, we conducted a meta-analysis of existing studies to boost statistical power.
  
  
  METHODS
  We used data from four projects: a) the Children's Hospital of Philadelphia (CHOP); b) phase I of the International Multicenter ADHD Genetics project (IMAGE); c) phase II of IMAGE (IMAGE II); and d) the Pfizer-funded study from the University of California, Los Angeles, Washington University, and Massachusetts General Hospital (PUWMa). The final sample size consisted of 2,064 trios, 896 cases, and 2,455 controls. For each study, we imputed HapMap single nucleotide polymorphisms, computed association test statistics and transformed them to z-scores, and then combined weighted z-scores in a meta-analysis.
  
  
  RESULTS
  No genome-wide significant associations were found, although an analysis of candidate genes suggests that they may be involved in the disorder.
  
  
  CONCLUSIONS
  Given that ADHD is a highly heritable disorder, our negative results suggest that the effects of common ADHD risk variants must, individually, be very small or that other types of variants, e.g., rare ones, account for much of the disorder's heritability.
authors: Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA.
authors: Benjamin M
authors: BM
authors: Neale
authors: Sarah E
authors: SE
authors: Medland
authors: Stephan
authors: S
authors: Ripke
authors: Philip
authors: P
authors: Asherson
authors: Barbara
authors: B
authors: Franke
authors: Klaus-Peter
authors: KP
authors: Lesch
authors: Stephen V
authors: SV
authors: Faraone
authors: Thuy Trang
authors: TT
authors: Nguyen
authors: Helmut
authors: H
authors: Schäfer
authors: Peter
authors: P
authors: Holmans
authors: Mark
authors: M
authors: Daly
authors: Hans-Christoph
authors: HC
authors: Steinhausen
authors: Christine
authors: C
authors: Freitag
authors: Andreas
authors: A
authors: Reif
authors: Tobias J
authors: TJ
authors: Renner
authors: Marcel
authors: M
authors: Romanos
authors: Jasmin
authors: J
authors: Romanos
authors: Susanne
authors: S
authors: Walitza
authors: Andreas
authors: A
authors: Warnke
authors: Jobst
authors: J
authors: Meyer
authors: Haukur
authors: H
authors: Palmason
authors: Jan
authors: J
authors: Buitelaar
authors: Alejandro Arias
authors: AA
authors: Vasquez
authors: Nanda
authors: N
authors: Lambregts-Rommelse
authors: Michael
authors: M
authors: Gill
authors: Richard J L
authors: RJ
authors: Anney
authors: Kate
authors: K
authors: Langely
authors: Michael
authors: M
authors: O'Donovan
authors: Nigel
authors: N
authors: Williams
authors: Michael
authors: M
authors: Owen
authors: Anita
authors: A
authors: Thapar
authors: Lindsey
authors: L
authors: Kent
authors: Joseph
authors: J
authors: Sergeant
authors: Herbert
authors: H
authors: Roeyers
authors: Eric
authors: E
authors: Mick
authors: Joseph
authors: J
authors: Biederman
authors: Alysa
authors: A
authors: Doyle
authors: Susan
authors: S
authors: Smalley
authors: Sandra
authors: S
authors: Loo
authors: Hakon
authors: H
authors: Hakonarson
authors: Josephine
authors: J
authors: Elia
authors: Alexandre
authors: A
authors: Todorov
authors: Ana
authors: A
authors: Miranda
authors: Fernando
authors: F
authors: Mulas
authors: Richard P
authors: RP
authors: Ebstein
authors: Aribert
authors: A
authors: Rothenberger
authors: Tobias
authors: T
authors: Banaschewski
authors: Robert D
authors: RD
authors: Oades
authors: Edmund
authors: E
authors: Sonuga-Barke
authors: James
authors: J
authors: McGough
authors: Laura
authors: L
authors: Nisenbaum
authors: Frank
authors: F
authors: Middleton
authors: Xiaolan
authors: X
authors: Hu
authors: Stan
authors: S
authors: Nelson
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D005260:Female; D056726:Genetic Association Studies; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics