Abstract: | Monoamine oxidase is an important enzyme in the catabolism of biogenic amines and can be measured in human platelets. Platelet MAO has been reported to be reduced in schizophrenic and manicdepressive patients, though other reports are contradictory. The present study evaluated the possibility that qualitative genetic enzyme abnormalities of MAO could be responsible for the different enzyme activities of platelet MAO in different populations. However, polyacrylamide gel electrophoresis of platelet MAO from 10 manic-depressive, 12 schizophrenic, and 11 normal individuals did not reveal any genetic mutant forms. |