Dopamine D4 receptor gene and personality dimensions in Brazilian male alcoholics

The presence of the seven-repeat allele of the VNTR in the exon 3 of the dopamine D4 receptor gene (DRD4) has been associated in healthy subjects to the personality trait of novelty seeking. The present study focuses these observations on a sample of Brazilian male alcoholics, evaluated on the temperament dimensions originally described by Cloninger. The genotypes observed are in agreement with those expected under Hardy-Weinberg equilibrium. Subjects with the seven-repeat allele manifest lower harm avoidance scores. No significant differences between subjects with or without the seven-repeat allele in the scores of novelty seeking or reward dependence were observed. The lack of association between novelty seeking and the DRD4 exon 3 polymorphism is further corroborated by the fact that the comorbid antisocial personality disorder is not associated to the presence of the seven-repeat allele. These results could be explained by a biological connection between the personality dimensions of novelty seeking and harm avoidance.