title: Candidate system analysis in ADHD: evaluation of nine genes involved in dopaminergic neurotransmission identifies association with DRD1.
abstract: OBJECTIVE
  Several pharmacological and genetic studies support the involvement of the dopamine neurotransmitter system in the aetiology of attention-deficit hyperactivity disorder (ADHD). Based on this information we evaluated the contribution to ADHD of nine genes involved in dopaminergic neurotransmission (DRD1, DRD2, DRD3, DRD4, DRD5, DAT1, TH, DBH and COMT).
  
  
  METHODS
  We genotyped a total of 61 tagging single nucleotide polymorphisms (SNPs) in a sample of 533 ADHD patients (322 children and 211 adults), 533 sex-matched unrelated controls and additional 196 nuclear ADHD families from Spain.
  
  
  RESULTS
  The single- and multiple-marker analysis in both population and family-based approaches provided preliminary evidence for the contribution of DRD1 to combined-type ADHD in children (P=8.8e-04; OR=1.50 (1.18-1.90) and P=0.0061; OR=1.73 (1.23-2.45)) but not in adults. Subsequently, we tested positive results for replication in an independent sample of 353 German families with combined-type ADHD children and replicated the initial association between DRD1 and childhood ADHD (P=8.4e-05; OR=3.67 (2.04-6.63)).
  
  
  CONCLUSIONS
  The replication of the association between DRD1 and ADHD in two European cohorts highlights the validity of our finding and supports the involvement of DRD1 in childhood ADHD.
authors.affiliation: Department of Psychiatry, Hospital Universitari Vall d'Hebron, and Department of Psychiatry and Legal Medicine, Universitat Autònoma de Barcelona, Barcelona, Catalonia, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Ribasés
authors.forename: Josep Antoni
authors.initials: JA
authors.lastname: Ramos-Quiroga
authors.forename: Amaia
authors.initials: A
authors.lastname: Hervás
authors.forename: Cristina
authors.initials: C
authors.lastname: Sánchez-Mora
authors.forename: Rosa
authors.initials: R
authors.lastname: Bosch
authors.forename: Anna
authors.initials: A
authors.lastname: Bielsa
authors.forename: Xavier
authors.initials: X
authors.lastname: Gastaminza
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Lesch
authors.forename: Andreas
authors.initials: A
authors.lastname: Reif
authors.forename: Tobias J
authors.initials: TJ
authors.lastname: Renner
authors.forename: Marcel
authors.initials: M
authors.lastname: Romanos
authors.forename: Andreas
authors.initials: A
authors.lastname: Warnke
authors.forename: Susanne
authors.initials: S
authors.lastname: Walitza
authors.forename: Christine
authors.initials: C
authors.lastname: Freitag
authors.forename: Jobst
authors.initials: J
authors.lastname: Meyer
authors.forename: Haukur
authors.initials: H
authors.lastname: Palmason
authors.forename: Miquel
authors.initials: M
authors.lastname: Casas
authors.forename: Mònica
authors.initials: M
authors.lastname: Bayés
authors.forename: Bru
authors.initials: B
authors.lastname: Cormand
mesh_terms: D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics*; D016022:Case-Control Studies; D002648:Child; D015331:Cohort Studies; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics*; D004299:Dopamine beta-Hydroxylase / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011954:Receptors, Dopamine / Q000235:genetics*; D017447:Receptors, Dopamine D1 / Q000235:genetics*; D013030:Spain
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; C493214:SLC6A3 protein, human; D004299:Dopamine beta-Hydroxylase