Polymorphisms in the dopamine D5 receptor (DRD5) gene and ADHD.

Abstract

There is considerable evidence to support a role of dopamine-related genes in the molecular aetiology of attention-deficit hyperactivity disorder (ADHD). A microsatellite located near the dopamine D5 receptor (DRD5) gene has been associated with ADHD in a number of studies, but other polymorphisms within the vicinity of this gene have not been examined. In this study we genotyped three microsatellites spanning the DRD5 region in a large clinical sample. Overall, we found little evidence to support a role for DRD5 in ADHD. We found no evidence of association with either the previously associated DRD5 marker, or a repeat in the promoter region of the gene. We did, however, find significant association for an allele of D4S615, a dinucleotide repeat located 131 kb 3' of DRD5 that has been previously associated with schizophrenia. A global test incorporating all alleles of this marker, however, was not significant and thus this finding needs replication before any conclusions can be made.