Platelet MAO activity in alcoholic patients and their first-degree relatives

The authors studied 49 alcoholic in patients in remission, 18 first- degree relatives of 10 of these alcoholics, and 25 normal control subjects. Alcoholic patients had significantly lower platelet monoamine oxidase (MAO) activity than control subjects. There was an inverse relationship between platelet MAO levels in the alcoholic patients and prevalence of reported alcoholism in their first-degree relatives. First-degree relatives of alcoholics had lower platelet MAO activity than control subjects. The data suggest a relationship between low platelet MAO activity and predisposition to familial alcoholism.