The genetics of addiction: alcohol-dependence and D3 dopamine receptor gene.

Alcohol-dependence is a complex phenotype, with behavioral, psychological, pharmacological, medical and social dimensions. Aggregation studies, adoption and twin researches have demonstrated that the vulnerability to alcohol-dependence is at least in part linked to genetic factors, the genetic vulnerability to alcoholism being mainly not substance-specific. There are numerous candidate genes, but the D3 dopamine receptor is specifically located in the limbic area, and in particular in the nucleus accumbens, which are involved in reward and reinforcement behavior. Furthermore, a previous collaborative study showed that homozygosity for the Ball DRD3 locus was more frequently observed in opiate dependent patients with high sensation seeking scores. In this study, we analyzed the distribution of Ball DRD3 polymorphism in a new sample of 131 French male alcoholic-patients (DSM III-R criteria) and 68 healthy controls matched for sex and origins. Although we replicated the higher sensation seeking score in alcohol-dependent patients with comorbid dependence, we found no significant difference in the DRD3 gene polymorphism between controls and alcoholic patients, regardless of sensation seeking score, addictive or psychiatric comorbidity, alcoholism typology, and clinical specificities of alcoholism. There is good evidence that gene coding for the dopamine receptor D3 does not play a major role in the genetic vulnerability to alcoholism.