MONOAMINE OXIDASES AND ALCOHOLISM .1. STUDIES IN UNRELATED ALCOHOLICSAND NORMAL CONTROLS

Low platelet MAO activity has been associated with alcoholism, In orde r to evaluate the role of MAO genes in susceptibility to alcoholism, w e have taken a biochemical and molecular genetic approach. The sample consisted of 133 alcoholic probands who were classified by subtypes of alcoholism and 92 normal controls, For those subjects typed for plate let MAO activity, alcoholics (N = 74) were found not to differ from th e non-alcoholics controls (N = 34), Neither was there a significant di fference between type I and type II alcoholics or between either subty pe and normal controls. However, we do find significant differences be tween male and female alcoholics, but not between male and female cont rols, The allele frequency distribution for the MAO-A and MAO-B dinucl eotide repeats is different between the alcoholic sample (N = 133) and the normal control sample (N = 92), In a two-way analysis of variance of MAO-B activity as a function of the allelic variation of each mark er locus and diagnosis, there is no evidence for mean differences in a ctivity levels for the different alleles, Our findings do not rule out a role for the MAO-B gene in controlling the enzyme activity because the dinucleotide repeats are located in introns. (C) 1995 Wiley-Liss, Inc.