Association of DRD4 exon III polymorphism with auditory P300 amplitude in 8-year-old children

Objectives: The present study was designed to investigate the association between the DRD4 genotype and auditory P300 amplitudes in a high-risk community sample. Methods: ERPs were elicited in 197 eight-year-olds (98 boys, 99 girls) using a passive and an active oddball task. Auditory stimuli of 60dB HL were presented binaurally at 1000 (standard stimulus) and 2000Hz (target stimulus). at a relative frequency ratio of 80:20. Two trial blocks of 250 stimuli each were collected. P300 amplitudes were analyzed from Fz, Cz and Pz. DNA was genotyped for the DRD4 exon III polymorphism. Results: A pattern of significant interactions of the DRD4 genotype with gender and experimental conditions was obtained. In both the active and the passive task, boys with at least one copy of the DRD4 7-repeat allele displayed significantly lower P300 amplitudes during the second trial block than boys carrying other alleles. Conclusions: This finding provides further evidence supporting it role of P300 amplitude reduction as an endophenotype for disinhibited psychopathology.