- Association of the dopamine receptor D4 (DRD4) gene with a refined phenotype of attention deficit hyperactivity disorder (ADHD): a family-based approach. Swanson, J.M., Sunohara, G.A., Kennedy, J.L., Regino, R., Fineberg, E., Wigal, T., Lerner, M., Williams, L., LaHoste, G.J., Wigal, S. Mol. Psychiatry (1998)