Dopamine D4 receptor exon III alleles and variation of novelty seeking in alcoholics

A dysfunction of dopaminergic neurotansmission has been implicated in alcohol-seeking behavior. Recently, a significant association between the seven-repeat allele (DRD4*7R) of a 16 amino acid motif in the third exon of the dopamine D4 receptor gene (DRD4) and the personality trait of novelty seeking has been reported. Our population-based association study tested the hypothesis that the DRD4*7R variant predisposes to high levels of novelty seeking, which may underlie alcohol-seeking behavior. The genotypes of the expressed DRD4 exon III polymorphism were determined in 197 German controls and 252 German alcohol-dependent males, of whom 92 alcoholics completed the tridimensional personality questionnaire. We found no significant differences in the DRD4*7R frequencies between controls and alcoholics, including two subgroups (56 alcoholics with dissocial personality disorder according to ICD-10 and 89 alcoholics with severe withdrawal symptoms) with a high level of novelty seeking. The novelty-seeking scores did not differ significantly between alcoholics (including both subgroups) carrying long alleles with six or more repeats compared with those lacking long alleles. The present results do not provide evidence that the DRD4*7R allele contributes a common and relevant effect to alcohol-seeking behavior in our sample of alcoholics.