[Combination of DRD4 and DAT1 genotypes is an important risk factor for attention deficit disorder with hyperactivity families living in Santiago, Chile].

Background: Attention deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurobiological disorder of childhood onset, characterized by hyperactivity, impulsiveness, and/or inattentiveness.

Aim: To search for possible associations between dopamine receptor D4 (DRD4) and dopamine transponder 1 (DATl) polymorphisms and ADHD in Chilean families.

Material And Methods: We extended a previous family-based discordant sib pair analysis that included 26 cases diagnosed according to DSM-IV criteria and 25 controls (healthy siblings of cases), adding 14 cases and 11 controls.