Young, S.E., Smolen, A., Corley, R.P., Krauter, K., DeFries, J.C., Crowley, T.J., & Hewitt, J.K. (2002). Dopamine transporter polymorphism associated with externalizing behavior problems in children. American Journal of Human Genetics, 114, 144-149.

We examined the relationship between parent reported externalizing behavior assessed at ages 4, 7, and 9 years and the VNTR polymorphism of the 3' untranslated region of SLC6A3 (DAT1) in a community sample of 790 children ascertained as part of our longitudinal twin and adoption studies. We have demonstrated that the 9-repeat variant of the DAT1 is a significant risk allele for externalizing behavior at ages 4 and 7 years.