No association between catechol-O-methyltransferase (COMT) gene polymorphism and attention deficit hyperactivity disorder (ADHD) in an Irish sample

Pharmacological and biochemical studies have indicated that imbalances in d opaminergic transmission may contribute to the aetiology of attention defic it hyperactivity disorder (ADHD). The enzyme catechol-O-methyltransferase ( COMT) plays a key role in the degradation of catecholamines such as dopamin e, L-DOPA, adrenaline, and noradrenaline and therefore could be considered as a candidate locus for ADHD susceptibility, We hypothesised that a propor tion of the genetic susceptibility to ADHD may be a consequence of dopamine depletion in the synapses due to high-level activity of the COMT gene (all ele 1), Using the haplotype-based haplotype relative risk method and 94 aff ected children and their parents genotyped for COMT alleles, we found no si gnificant differences in the frequency of the transmitted and nontransmitte d alleles to ADHD cases from their parents. The absence of association betw een COMT alleles and ADHD indicated that this locus does not play a signifi cant role or at least a role independent of other genes, in predisposing to ADHD in the Irish population. Am. J, Med, Genet, (Neuropsychiatr. Genet,) 96:282-284, 2000. (C) 2000 Wiley-Liss, Inc.