title: Intelligence in DSM-IV combined type attention-deficit/hyperactivity disorder is not predicted by either dopamine receptor/transporter genes or other previously identified risk alleles for attention-deficit/hyperactivity disorder.
abstract: A major goal of genetic studies of attention deficit hyperactivity disorder (ADHD) is to identify individual characteristics that might help segregate the disorder's inherent heterogeneity. [Mill et al. (2006); Arch Ger Psychiatry 63:462-469] recently reported a potentially important association between two dopamine-related risk polymorphisms (DRD4 variable number tandem repeat (VNTR) in exon 3 and DAT1 VNTR in the 3' UTR) and lowered IQ in ADHD. The objective of the current study was to replicate the [Mill et al. (2006); Arch Ger Psychiatry 63:462-469] findings in a clinical sample and to extend the analysis to a large range of alternative SNP markers of putative ADHD risk alleles identified in a recent study [Brookes et al. (2006); Mol Genet 11:934-953]. Participants were 1081 children and adolescents with a research-confirmed combined type ADHD diagnosis and 1300 unaffected siblings who took part in the International Multi-centre ADHD Genetics (IMAGE) project. They were recruited from multiple settings from across Europe: Belgium, Britain, Germany, Ireland, Israel, Netherlands, Spain and Switzerland. The results were that ADHD was associated with reduced IQ. However, there was no association between the two dopamine-related risk polymorphisms and IQ in either the probands or their siblings. Furthermore, other selected genetic markers previously demonstrated to be associated with ADHD in this sample were not associated with IQ. This large scale study with a clinically ascertained and regorously diagnosed sample failed to replicate the association between genetic polymorphisms in the dopamine system and IQ in ADHD. We also observed no association of other SNPs with IQ in ADHD.
authors.affiliation: School of Psychology, University of Southampton, Southampton, UK. ejb3@soton.ac.uk
authors.forename: Edmund J S
authors.initials: EJ
authors.lastname: Sonuga-Barke
authors.forename: Keeley-Joanne
authors.initials: KJ
authors.lastname: Brookes
authors.forename: Jan
authors.initials: J
authors.lastname: Buitelaar
authors.forename: Richard
authors.initials: R
authors.lastname: Anney
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Bitsakou
authors.forename: Dieter
authors.initials: D
authors.lastname: Baeyens
authors.forename: Cathelijne
authors.initials: C
authors.lastname: Buschgens
authors.forename: Wai
authors.initials: W
authors.lastname: Chen
authors.forename: Hanna
authors.initials: H
authors.lastname: Christiansen
authors.forename: Jacques
authors.initials: J
authors.lastname: Eisenberg
authors.forename: Jonna
authors.initials: J
authors.lastname: Kuntsi
authors.forename: Iris
authors.initials: I
authors.lastname: Manor
authors.forename: Amanda
authors.initials: A
authors.lastname: Meliá
authors.forename: Aisling
authors.initials: A
authors.lastname: Mulligan
authors.forename: Nanda
authors.initials: N
authors.lastname: Rommelse
authors.forename: Ueli C
authors.initials: UC
authors.lastname: Müller
authors.forename: Henrik
authors.initials: H
authors.lastname: Uebel
authors.forename: Tobias
authors.initials: T
authors.lastname: Banaschewski
authors.forename: Richard
authors.initials: R
authors.lastname: Ebstein
authors.forename: Barbara
authors.initials: B
authors.lastname: Franke
authors.forename: Michael
authors.initials: M
authors.lastname: Gill
authors.forename: Ana
authors.initials: A
authors.lastname: Miranda
authors.forename: Robert D
authors.initials: RD
authors.lastname: Oades
authors.forename: Herbert
authors.initials: H
authors.lastname: Roeyers
authors.forename: Aribert
authors.initials: A
authors.lastname: Rothenberger
authors.forename: Joseph
authors.initials: J
authors.lastname: Sergeant
authors.forename: Hans Christoph
authors.initials: HC
authors.lastname: Steinhausen
authors.forename: Margaret
authors.initials: M
authors.lastname: Thompson
authors.forename: Eric
authors.initials: E
authors.lastname: Taylor
authors.forename: Philip
authors.initials: P
authors.lastname: Asherson
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Faraone
mesh_terms: D000293:Adolescent; D000483:Alleles; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics / Q000523:psychology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007360:Intelligence; D008297:Male; D011954:Receptors, Dopamine / Q000235:genetics*; D012307:Risk Factors
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D011954:Receptors, Dopamine