American Journal of Medical Genetics Part B (Neuropsychiatric Genetics) 147B:397–402 (2008) Brief Research Communication An Exploratory Study of the Relationship Between Four Candidate Genes and Neurocognitive Performance

Since neurocognitive performance is a possible endophenotype for Attention Deficit Hyperactiv-ity Disorder (ADHD) we explored the relationship between four genetic polymorphisms and neuro-cognitive performance in adults with ADHD. We genotyped a sample of 45 adults with ADHD at four candidate polymorphisms for the disorder (DRD4 48 base pair (bp) repeat, DRD4 120 bp duplicated repeat, SLC6A3 (DAT1) 40 bp variable number of tandem repeats (VNTR), and COMT Val158Met). We then sub-grouped the sample for each poly-morphism by genotype or by the presence of the (putative) ADHD risk allele and compared the performance of the subgroups on a large battery of neurocognitive tests. The COMT Val158Met poly