MAOA gene aggressive behavior

MAOA activity have been implicated in a wide range of psychiatric disorders. Deficiency in MAOA enzyme activity due to a hemizygous chain termination mutation of the MAOA gene has recently been shown to be associated with impulsive aggression and hypersexual behavior in affected males from a single extended pedigree (Brunner syndrome) (Brunner et al. 1993). 

Monoamine oxidase A (MAOA) seems to be the principal serotonin degrading enzyme. The gene is located on chromosome Xpll [77]. Recent reports have shown that a low activity genetic variant of monoamine oxidase A (MAOA) is likely to be related to aggressive behavior, but only when paired with abusive experience in childhood. It also has been found that the low activity form of MAOA was associated with more adult symptoms of antisocial alcoholism than the high activity variant [113]. No studies related to autism have been carried out with this polymorphism (for more details see section 5 in Serotonergic innervations). 

Fig. 6.6 (a) Section of the double helix of the gene expressing the enzyme MAOA. (b) C-t 1 corgyllne PEf scan showing the regional distribution In the brain of the MAOA enzyme, (c) Aggressive subject, (d) Aggressive behavior. 

Brunner et al. (1993) found that aggressive behavior was associated with a mutation of the gene for the enzyme MAOA (Science 262 578-580,1993). In men with borderline mental retardation and aggressive tendencies, they found greatiy reduced MAO activity. Mutations of the C936T gene were related to criminal/antisocial behavior. 

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