ADH1B and alcohol dependence: Clinically, a study in Ashkenazic Jewish American college students reported that individuals carrying an alcohol dehydrogenase enzyme allele (ADH1B*2) that codes for an isoform that is one order of magnitude more active than that coded by the usual ADH1B*1 (ref. 70) are also protected against heavy alcohol use and alcoholism.71 No genetic vulnerability or risk alleles for alcoholism have been reported in bipolar patients.