Recent advances in the genetics of attention deficit hyperactivity disorder.

In the past few years, interest in the molecular genetics of attention deficit hyperactivity disorder (ADHD) has grown enormously, with many groups searching for susceptibility genes, often through large collaborative efforts facilitated by the International ADHD Genetics Consortium. Association findings for several candidate genes within the dopaminergic system, the DRD4 and DRD5 receptor genes and the dopamine transporter gene, DAT1, have been well replicated, and the first of several ongoing genome linkage scan study results have been published. Current challenges in this field are to identify the actual functional variant(s) in these genes conferring susceptibility and other genetic and environmental risk factors for ADHD.