Genetic association between reduced P300 amplitude and the DRD2 dopamine receptor A1 allele in children at high risk for alcoholism

Background: There is evidence that both reduction in P300 amplitude and the presence of the Al allele are risk markers for alcoholism We hypothesized that demonstration of a relationship between the marker and the trait in young children who had nor begun to drink regularly would provide evidence for dopaminergic mediation of the reduction in P300 often seen among high-risk children. A previous association between the Al and the P300 amplitude in screened controls supports the hypothesis that this association occurs in the general population. Methods: Children were assessed using both visual and auditory paradigms to elicit event-related potentials (ERPs). The P300 component of the ERP was investigated with respect to the genetic variation of the Taq1A D2 receptor in these children. Results: Generic association between a marker locus (Taq1 A RFLP near the D2 receptor locus) and the amplitude of P300 was found to be present in 58 high-risk children and their relatives (a total of 100 high-risk individuals). Conclusions: A higher proportion of children from alcoholic families may exhibit lower P300 because more of these children carry the Al allele than is seen in the normal population. (C) 1998 Society of Biological Psychiatry.