Association of the dopamine transporter gene and ADHD symptoms in a Canadian population-based sample of same-age twins.
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.
Ouellet-Morin
Isabelle
I
Genetics and Development Division, Toronto Western Research Institute, University Health Network, Toronto, Canada.
Wigg
Karen G
KG
Feng
Yu
Y
Dionne
Ginette
G
Robaey
Philippe
P
Brendgen
Mara
M
Vitaro
Frank
F
Simard
Louise
L
Schachar
Russell
R
Tremblay
Richard E
RE
Pérusse
Daniel
D
Boivin
Michel
M
Barr
Cathy L
CL
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
D050483:Dopamine Plasma Membrane Transport Proteins; D005819:Genetic Markers; C493214:SLC6A3 protein, human