Only males were affected. They showed borderline mental retardation (IQ scores around 85) with prominent behavioral disturbances including aggressive and sometimes violent behavior, arson, attempted rape, and exhibitionism. Aggressive behavior was usually triggered by anger and tended to cluster in periods of 1-3 days. During this time the affected male would experience frequent night terror. Several affected males were reported to suddenly grasp or hold female relatives. All patients displayed a tendency toward stereotyped hand movements such as hand wringing, plucking, or fiddling. Growth and morphology were normal. All of the females functioned normally.

Marked elevations were noted in the MAO substrates such as serotonin, normetanephrine, 3-methoxytyramine, and tyramine in the urine. Levels of the MAO products vanillylmandelic acid, homovanilic, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenylglycol, however, were reduced. As platelet MAO-B activity was found to be normal, these results are consistent with a deficiency of MAO-A, the isozyme found in neural tissue.

The discovery of this disorder suggests that it might be worthwhile to perform systematic urinary monoamine analysis in unexplained significant behavior disturbances, particularly when occurring in several male family members.

No efficient treatment is known at the present time. Both the borderline mental retardation and the behavior abnormalities seem to have a stable evolution. No patient has been institutionalized because of mental retardation.

The locus for this disease has been assigned to the Xp11-21 region. A point mutation was identified in the eight exon of the MAO-A structural gene which changes a glutamine to a termination codon.