Attention Deficit-Hyperactivity Disorder 2, also known as attention deficit-hyperactivity disorder, susceptibility to, 2, is related to attention deficit-hyperactivity disorder 3 and attention deficit-hyperactivity disorder. An important gene associated with Attention Deficit-Hyperactivity Disorder 2 is ADHD2 (Attention Deficit-Hyperactivity Disorder, Susceptibility To, 2).