We are investigating two aspects of alcohol dehydrogenase genes that might influence the amount of alcohol dehydrogenase activity in humans: polymorphisms that result in enzyme subunits that differ in kinetic properties, and differences in gene expression. We have found that those polymorphic alleles that encode isozymes which are predicted to metabolize ethanol faster are under-represented in alcoholics in an Oriental population. We have also found two cis-acting promoter sequences that are important for transcription of the human ADH2 gene.