A family-based association study of attention-deficit hyperactivity disorder and dopamine D2 receptor TaqI A alleles.

Over the past 5 years, considerable progress has been made in the identification of polymorphic variation within monoamine system genes that are associated with the attention-deficit hyperactivity disorder (ADHD) phenotype. In this study, we investigated the association of the dopamine D2 receptor (DAD2) TaqI A and ADHD in a Taiwanese sample. The sample consisted of 98 children with ADHD and 154 of their parents. ADHD cases were ascertained from the Child Psychiatric Clinics at Chang Gung Memorial Hospital in the Taipei area, Taiwan. A diagnosis of ADHD was made following clinical interviews plus completion of a standard maternal interview and Conner's revised rating scales by a parent and teacher. Association of DRD2 TaqI A polymorphism in this sample was investigated using a haplotype-based haplotype relative-risk method. Among our subjects, there was no significant difference in transmission rates between DRD2 TaqI A1 and A2 alleles. The results of this study do not support DRD2 playing a major role in Taiwanese children with ADHD.