[Contribution of genetics to the concept of risk status for alcohol dependence]

The factors involved in the variability of one's own risk for alcohol dependence is multifactorial and mostly unknown. Nevertheless, genetic factors are clearly involved in the risk for the disorder, the impact of addictive genetic factors being evaluated between 30% and 50%. Aggregation studies underline the difficulties of delimiting the boundaries of the phenotype, as some subgroups of alcohol-dependent patients have genetic factors with an increased weight (severe and young-onset disorder, presence of antisocial behavior...). Furthermore, familial studies also showed that the genetic of "addiction" may be more relevant than studying the genetic of one specific dependence. The use of one substance lately abused being probably more dependent of familial and/or environmental features. The discover of susceptibility genes had a greater impact on defining the phenotype than proposing new treatments. Three examples are given in this review. Firstly, le gene coding for the second dopamine receptor may be more specifically involved in severe and comorbid alcohol-dependence. Secondly, the gene coding for the serotonin transporter may increase the suicidal risk in alcohol-dependent patients. Thirdly, the quality of the withdrawal process is partly explained by the existence of a specific genotype of the dopamine transport gene.