Polymorphisms at the DRD2 locus in early-onset alcohol dependence in the Indian population

The susceptibility to alcohol dependence is probably of polygenic origin. A ssociation studies have attempted to identify possible candidate genes that may contribute to the risk to developing dependence. Severe for ms of the alcoholism phenotype have been associated with an increased frequency of th e Taq A1 allele at the DRD2 locus. Ethnic stratification and non-comparable phenotype may have contributed to the contradictory results in previous st udies. We identified probands, using the Schedules of Assessment of Neurops ychiatry (SCAN) schedule, who had onset of alcohol dependence (ICD-10) befo re 25 years of age. Family members were inter viewed using the Family Inter view for Genetic Studies (FIGS) schedule to identify patients who had two first-degree relatives with alcohol dependence. Fifty subjects who fulfille d the criteria were selected for the study. These were compared to a nor ma l population from a similar background. The allele frequencies did not diff er between the two groups. The Taq1a polymorphism does not seem to be assoc iated with alcoholism in this group of severely affected, young age of onse t probands in the southern Indian population.