Erythrocyte aldehyde dehydrogenase was demonstrated to be suitable as a peripheral trait marker for alcohol dependence.[132] Single nucleotide polymorphism of the ALDH 2 gene has been studied in six Indian populations and provides the baseline for future studies in alcoholism.[133] An evaluation of ADH 1B and ALDH 2 gene polymorphism in alcohol dependence showed a high frequency of the ALDH2*2/*2 genotype among alcohol-dependent subjects.[134] DRD2 polymorphisms have been studied in patients with alcohol dependence, but a study in an Indian population failed to show a positive association. The gene discussed is DRD2; the disease is alcohol dependence.