Evidence for linkage of a tandem duplication polymorphism upstream of the dopamine D4 receptor gene (DRD4) with attention deficit hyperactivity disorder (ADHD)
Department of Psychiatry and Biobehavioral Scienes, UCLA Neuropsychiatric Institute, Mental Retardation Research Center, UCLA School of Medicine, Los Angeles, CA 90024-1759, USA. jmccracken@mednet.ucla.edu