title: Meta-analysis of family-based association studies between the dopamine transporter gene and attention deficit hyperactivity disorder.
abstract: BACKGROUND
  Molecular genetic research has mainly focused on the D4 dopamine receptor (DRD4) and the dopamine transporter (DAT) genes in attention-deficit hyperactivity disorder (ADHD). A recent meta-analysis showed that the DRD4 gene has a significant role in the vulnerability to ADHD.
  
  
  OBJECTIVE
  With an equal number of positive and negative association studies between the 10-repeat of the DAT gene and ADHD, a meta-analysis is required for this other candidate gene.
  
  
  METHODS
  We re-analysed the 13 published family-based association studies between ADHD and the DAT gene. Following recent recommendations, different biases were specifically assessed, such as the sample-size effect and the time effect.
  
  
  RESULTS
  The meta-analysis showed no significant association between ADHD and the DAT gene (P = 0.21), but an important between-samples heterogeneity (P = 0.0009). Odds ratios above 1 are mostly observed in studies with a small number of informative transmissions, and decrease with larger sample size.
  
  
  CONCLUSIONS
  Contrary to what was found for the DRD4 gene, the 10-repeat allele of the DAT gene has at most a minor role in the genetic susceptibility of ADHD. The different biases detected herein probably explain the initial impression of a significant impact of the DAT gene on hyperactivity.
authors.affiliation: CHU Robert Debré (AP-HP, Paris VII), Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Purper-Ouakil
authors.forename: M
authors.initials: M
authors.lastname: Wohl
authors.forename: M C
authors.initials: MC
authors.lastname: Mouren
authors.forename: P
authors.initials: P
authors.lastname: Verpillat
authors.forename: J
authors.initials: J
authors.lastname: Adès
authors.forename: P
authors.initials: P
authors.lastname: Gorwood
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics*; D016001:Confidence Intervals; D016208:Databases, Factual; D050483:Dopamine Plasma Membrane Transport Proteins; D005190:Family; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016017:Odds Ratio; D017448:Receptors, Dopamine D2 / Q000235:genetics; D050638:Receptors, Dopamine D4
chemical_list: C493599:DRD4 protein, human; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D017448:Receptors, Dopamine D2; C493214:SLC6A3 protein, human; D050638:Receptors, Dopamine D4