Candidate Gene

• The enzyme MAOA (Monoamine Oxidase A) breaks down important neurotransmitters such as serotonin, noradrenaline and dopamine. These neurotransmitters control aggression.
• Production of MAOA is based on the MAOA gene located on the X chromosome.
• Inheriting a functional MAOA gene leads to adequate levels of the MAOA enzyme being produced.
• A normal level of the MAOA enzyme means that neurotransmitters are inactivated after carrying impulses from one neuron to another, and no longer have an effect on the post-synaptic neuron.
• This normalises the levels of neurotransmitters like serotonin in the synapse, which reduces the chances of aggression.
• Any disruption in the MAOA gene leads to abnormal levels and activity of the MAOA enzyme, which leads to the abnormal breakdown of neurotransmitters like serotonin, leading to an abnormal amount of serotonin in the brain.
• Inheriting a faulty version of the MAOA gene (the warrior gene) leads to very low MAOA activity in areas of the brain, abnormal levels of neurotransmitters and high levels of aggression.