Association of monoamine oxidase (MAO) activity with alcoholism and alcoholic subtypes

A familial/genetic study of platelet monoamine oxidase (MAO) activity in alcoholics was carried out. MAO activities were determined using phenylethylamine (PEA) as substrate at Km concentration (1.2 microM) and at saturating concentration (12.0 microM). Complex segregation analysis of familial data indicated a single major gene mode of transmission of activity at both substrate concentrations. In addition, the present sample size (13 families, 108 members) proved sufficient to allow correlation analysis of enzyme activity with affection status and clinical subtypes of affecteds. MAO activity was significantly correlated with alcoholism at both Km and saturating substrate concentrations and a significant correlation between low MAO activity and Cloninger Type II alcoholism was seen at Km substrate concentration. These results confirm a hierarchical cosegregation of platelet MAO activity and alcoholism suggesting that MAO activity warrants continued status as a marker in alcoholism.