title: Genetic basis of attention deficit and hyperactivity.
abstract: BACKGROUND
  Hyperkinetic disorder or attention-deficit hyperactivity disorder (ADHD) is an important clinical condition.
  
  
  OBJECTIVE
  The research evidence for a genetic contribution to ADHD is reviewed.
  
  
  METHODS
  Measurement of the phenotype, the extent to which attention deficit and hyperactivity are heritable and molecular genetic findings are discussed. Future research directions are also considered.
  
  
  RESULTS
  ADHD is a familial disorder. Available adoption evidence suggests genetic influences are important. Twin studies have primarily focused on trait measures which have consistently been found to be highly heritable Molecular genetic studies of clinical disorder so far have suggested the involvement of the dopamine DRD-4 receptor gene and dopamine transporter gene (DAT1). However, these findings await further replication.
  
  
  CONCLUSIONS
  Advances in psychiatric genetics and current research interest in the genetics of ADHD should improve our understanding of aetiological factors and have an impact on treatment.
authors.affiliation: Department of Child and Adolescent Psychiatry, University of Manchester, Royal Manchester Children's Hospital, Pendlebury.
authors.forename: A
authors.initials: A
authors.lastname: Thapar
authors.forename: J
authors.initials: J
authors.lastname: Holmes
authors.forename: K
authors.initials: K
authors.lastname: Poulton
authors.forename: R
authors.initials: R
authors.lastname: Harrington
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics; D015897:Comorbidity; D050483:Dopamine Plasma Membrane Transport Proteins; D020022:Genetic Predisposition to Disease; D006801:Humans; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D010375:Pedigree; D017448:Receptors, Dopamine D2 / Q000235:genetics; D050638:Receptors, Dopamine D4; D018433:Twin Studies as Topic
chemical_list: D002352:Carrier Proteins; 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