Monoamine Oxidase A - Aggression and The "Warrior Gene"

Aggression and The "Warrior Gene"

A version of the monoamine oxidase-A gene has been popularly referred to as the warrior gene. Several different versions of the gene are found in different individuals, although a functional gene is present in most humans (with the exception of a few individuals with Brunner syndrome). In the variant, the allele associated with behavioural traits is shorter (30 bases) and may produce less MAO-A enzyme. This gene variation is in a regulatory promoter region about 1000 bases from the start of the region that encodes the MAO-A enzyme.

The frequency distribution of variants of the MAOA gene differs between ethnic groups. 59% of African-American men, 56% of Maori men, 54% of Chinese men, and 34% of Caucasian men carry the 3R allele. 5.5% of African-American men, 0.1% of Caucasian men, and 0.00067% of Asian men carry the 2R allele.

A connection between a version of the monoamine oxidase A gene (3R) and several types of antisocial behavior has been found. MAOA had no statistically significant main effect on antisocial behavior. Maltreated children with genes causing high levels of MAO-A were less likely to develop antisocial behavior. Low MAO-A activity in combination with abuse experienced during childhood results in an increased risk of aggressive behaviour as an adult. High testosterone, maternal tobacco smoking during pregnancy, poor material living standards, dropping out of school, and low IQ can also trigger violent behavior in men with the low-activity alleles (which are overwhelmingly the 3R allele).

In individuals with the low activity MAOA gene, when faced with social exclusion or ostracism showed considerably higher levels of aggression than individuals with the high activity MAOA gene. Low activity MAO-A could significantly predict aggressive behaviour in a high provocation situation, but was less associated with aggression in a low provocation situation. Individuals with the low activity variant of the MAOA gene were just as likely as participants with the high activity variant to retaliate when the loss was small. However, they were considerably more likely to retaliate and with greater force when the loss was large.

“Monoamine oxidases (MAOs) are enzymes that are involved in the breakdown of neurotransmitters such as serotonin and dopamine and are, therefore, capable of influencing feelings, mood, and behaviour of individuals”. According to this, it would mean that if there was a mutation to the gene that is involved in the process of promoting or inhibiting MAO enzymes it could affect a person’s personality or behaviour and could therefore make them more prone to aggression. A deficiency is the MAOA gene has shown higher levels in aggression in males which could further stimulate more research into this controversial topic “A deficiency in monoamine oxidase A (MAOA) has been shown to be associated with aggressive behaviour in men of a Dutch family”. These finding suggest that further research is needed in this topic of debate.