A twin study on three enzymes (DBH, COMT, MAO) of catecholamine metabolism. Correlations with MMPI.

Ina a sample of 48 healthy adult male twin pairs (24 MZ, 24 DZ) the activities of DBH (serum), COMT (red blood cells), and MAO (platelets) were determined. The twins had undergone a detailed psychodiagnostic test procedure before. Interindividual variability of enzyme activities is almost exclusively genetically determined. No correlation between enzyme activities within one subject is found. Correlations between enzyme activities and MMPI test scores were calculated. As in a comparable investigation by Murphy et al. (1977), negative correlations between MAO activity and MMPI scores prevailed.