Abstract

Given the spectacular advances of genetics during the last five years, it seems appropriate to revisit the important subject of genetics of alcoholism and substance abuse. In recent studies alcohol abuse was shown to have an heredability of roughly 38%, whereas psychostimulant and opiate use exhibit hereability of 11 to 45%. The hereability of smoking was found to be around 50%. There is a strong comorbidity between alcoholism and smoking. More than 80% of alcoholics smoke cigarettes in the U.S.A.. Other genetic methods such as linkage analysis, allele sharing methods, association studies and analysis of inbred, transgenetic and gene-knockout rodents, have partially agreed in showing that the 5HT-IB serotonin receptor and the DRD1, DRD2, and DRD4 dopamine receptors, as well as the dopamine transporter DAT, play an important role in behaviors related to alcoholism and substance abuse. Some neurochemical markers as for example monoamine oxidase and adenylate cyclase have also been implicated in addictive disorders. The aldebyde dehydrogenase allele ALDH2*2 has a protective effect against alcoholism. Two whole genome linkage studies have shown linkage to chromosomal regions that are in the proximity of the DRD4 dopamine receptor, the GABA receptor gene cluster and the alcohol dehydrogenase gene cluster.