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

The susceptibility to alcohol dependence is probably of polygenic origin. Association studies have attempted to identify possible candidate genes that may contribute to the risk to developing dependence. Severe forms of the alcoholism phenotype have been associated with an increased frequency of the Taq A1 allele at the DRD2 locus. Ethnic stratification and non-comparable phenotype may have contributed to the contradictory results in previous studies. We identified probands, using the Schedules of Assessment of Neuropsychiatry (SCAN) schedule, who had onset of alcohol dependence (ICD-10) before 25 years of age. Family members were interviewed using the Family Interview for Genetic Studies (FIGS) schedule to identify patients who had two first-degree relatives with alcohol dependence. Fifty subjects who fulfilled the criteria were selected for the study. These were compared to a normal population from a similar background. The allele frequencies did not differ between the two groups. The Taq1a polymorphism does not seem to be associated with alcoholism in this group of severely affected, young age of onset probands in the southern Indian population.