Interaction of dopamine transporter genotype with prenatal smoke exposure on ADHD symptoms.
OBJECTIVE
To demonstrate that children homozygous for the 10-repeat allele of the common dopamine transporter (DAT1) polymorphism who were exposed to maternal prenatal smoke exhibited significantly higher hyperactivity-impulsivity than children without these environmental or genetic risks.


METHODS
We performed a prospective longitudinal study from birth into early adulthood monitoring the long-term outcome of early risk factors. Maternal prenatal smoking was determined during a standardized interview with the mother when the child was 3 months old. At age 15 years, 305 adolescents participated in genotyping for the DAT1 40 base pair variable number of tandem repeats polymorphism and assessment of inattention, hyperactivity-impulsivity, and oppositional defiant/conduct disorder symptoms with the Kiddie-Sads-Present and Lifetime Version.


RESULTS
There was no bivariate association between DAT1 genotype, prenatal smoke exposure and symptoms of attention deficit hyperactivity disorder. However, a significant interaction between DAT1 genotype and prenatal smoke exposure emerged (P = .012), indicating that males with prenatal smoke exposure who were homozygous for the DAT1 10r allele had higher hyperactivity-impulsivity than males from all other groups. In females, no significant main effects of DAT1 genotype or prenatal smoke exposure or interaction effects on any symptoms were evident (all P > .25).


CONCLUSIONS
This study provides further evidence for the multifactorial nature of attention deficit hyperactivity disorder and the importance of studying both genetic and environmental factors and their interaction.
Becker
Katja
K
Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany.
El-Faddagh
Mahha
M
Schmidt
Martin H
MH
Esser
Günter
G
Laucht
Manfred
M
D000293:Adolescent; D000483:Alleles; D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology* / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics*; D004777:Environment; D005260:Female; D005838:Genotype; D006720:Homozygote; D006801:Humans; D008297:Male; D008957:Models, Genetic; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012044:Regression Analysis; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D050483:Dopamine Plasma Membrane Transport Proteins; D014028:Tobacco Smoke Pollution