MAOA (Monoamine Oxidase A) is a mitochondrial flavoenzyme that catalyzes the oxidative deamination of primary amines, particularly neurotransmitters including serotonin, dopamine, and other biogenic amines 1. The enzyme preferentially metabolizes serotonin and converts these substrates to corresponding aldehydes with concomitant hydrogen peroxide production 1. MAOA functions critically in regulating monoamine levels in the central nervous system and peripheral tissues, with implications for behavior and metabolism. Genetically, complete MAOA deficiency causes Brunner syndrome, characterized by borderline mental retardation and impulsive aggression, arson, and abnormal sexual behavior, associated with disturbed monoamine metabolism 2. Low-activity MAOA variants, particularly the rare 2-repeat allele, confer increased risk for violent behaviors including shooting and stabbing, especially in males with childhood maltreatment history—representing the best-documented gene×environment interaction in aggression pathophysiology 34. Beyond neuropsychiatric manifestations, decreased MAOA expression correlates with advanced pancreatic and prostate cancer stages, where reduced serotonin degradation promotes tumor growth through HTR2B signaling and glycolytic reprogramming 56. MAOA inhibitors show therapeutic potential in Parkinson's disease and cancer immunotherapy, exerting neuroprotective effects through oxidative stress reduction and immune modulation 16.