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

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. © 2003 Wiley‐Liss, Inc.