The fact that both the dopamine transporter knockout mouse (DAT KO) and rats with neonatal 6-hydroxydopamine (6-OHDA) lesions are also hyperactive, and are considered animal models of ADHD, supports the view that dopamine is integral to the ADHD syndrome (see Solanto, 1998, 2002 for review). The gene discussed is SLC6A3; the disease is attention deficit-hyperactivity disorder.