title: Association of the dopamine transporter gene and ADHD symptoms in a Canadian population-based sample of same-age twins.
abstract: Attention deficit hyperactivity disorder (ADHD) is the most prevalent psychiatric disorder emerging during childhood. Psychostimulant medications (e.g., methylphenidate) noticeably reduce ADHD symptoms in most children. Since methylphenidate inhibits dopamine transporter activity, the dopamine transporter gene (DAT1) was considered to be the prime candidate risk gene in ADHD. Several studies found evidence for an association between the 10-repeat allele of the variable number of tandem repeat (VNTR) located in the 3' untranslated region and ADHD and/or ADHD symptoms in clinical and population-based samples. However, this finding was not replicated in all samples. In this study, we investigated the association between the DAT1 gene and ADHD symptoms in a population-based twin sample from Québec (Canada). We used two polymorphisms, the VNTR and rs27072, the last providing the most significant results in a clinical sample from Toronto (Ontario, Canada). No association was noted between the VNTR and ADHD symptoms in children at 6 and 7 years of age, as reported by teachers. However, a significant association was found for the rs27072 polymorphism and symptoms of inattention and hyperactivity/impulsivity. These findings indicate that the DAT1 gene contributes to ADHD symptoms in this sample and further suggest that the VNTR may not be the optimal polymorphism for study in all populations.
authors.affiliation: Genetics and Development Division, Toronto Western Research Institute, University Health Network, Toronto, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Ouellet-Morin
authors.forename: Karen G
authors.initials: KG
authors.lastname: Wigg
authors.forename: Yu
authors.initials: Y
authors.lastname: Feng
authors.forename: Ginette
authors.initials: G
authors.lastname: Dionne
authors.forename: Philippe
authors.initials: P
authors.lastname: Robaey
authors.forename: Mara
authors.initials: M
authors.lastname: Brendgen
authors.forename: Frank
authors.initials: F
authors.lastname: Vitaro
authors.forename: Louise
authors.initials: L
authors.lastname: Simard
authors.forename: Russell
authors.initials: R
authors.lastname: Schachar
authors.forename: Richard E
authors.initials: RE
authors.lastname: Tremblay
authors.forename: Daniel
authors.initials: D
authors.lastname: Pérusse
authors.forename: Michel
authors.initials: M
authors.lastname: Boivin
authors.forename: Cathy L
authors.initials: CL
authors.lastname: Barr
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics* / Q000503:physiopathology; D002170:Canada; D002648:Child; D004200:Diseases in Twins / Q000235:genetics*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics*; D005260:Female; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D018895:Microsatellite Repeats; D011110:Polymorphism, Genetic; D044382:Population Groups / Q000235:genetics; D014427:Twins / Q000235:genetics*; D014429:Twins, Dizygotic
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D005819:Genetic Markers; C493214:SLC6A3 protein, human