Monoamine oxidase A (MAOA, EC 1.4.3.4) is responsible for the degradation of biogenic amines, including the neurotransmitters epinephrine, nor-epinephrine, dopamine and serotonin. MAOA is localized to Xp11.4-Xp11.3. A nonsense mutation in humans causes a truncation of the protein, resulting in the loss of MAOA activity (Brunner et al. 1993). Males with this mutation have engaged in impulsive/aggressive behaviors including rape, arson and assault (Brunner et al. 1993). Similarly, a mutation in transgenic mice yields a non-functioning enzyme that is also associated with increased aggressiveness and injury among male mice and their cage-mates (Cases et al. 1995). The MAOA promoter region contains a variable number tandem repeat (VNTR) polymorphism with suggested effects on mRNA transcription efficiency and may be associated with antisocial behavior (Craig, 2005).
