The MAOA gene is a gene that provides instructions for making an enzyme called monoamine oxidase A. This enzyme is important for breaking down certain neurotransmitters in the brain, such as serotonin, dopamine, and norepinephrine. By regulating these chemicals, the MAOA gene plays a role in mood, behavior, and emotional responses. Variations in the MAOA gene can influence an individual's risk for certain psychological conditions, including depression and anxiety disorders. Some studies suggest that specific gene variants may be linked to aggressive behavior, but the relationship is complex and influenced by environmental factors as well.