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MAOA gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MAOA gene

The MAOA gene provides instructions for making the monoamine oxidase A enzyme, which is responsible for breaking down neurotransmitters and dietary amines.

Normal Function

The MAOA gene provides instructions for making an enzyme called monoamine oxidase A. This enzyme breaks down molecules called monoamines through a chemical reaction known as oxidation. Among the monoamines broken down by monoamine oxidase A are certain chemicals that act as neurotransmitters, including serotonin, epinephrine, norepinephrine, and dopamine. These neurotransmitters regulate mood, emotion, sleep, appetite, stress response, and physical movement.

Monoamine oxidase A also helps break down monoamines found in the diet, such as tyramine. Additionally, the enzyme appears to be involved in normal brain development before birth, playing a role in the controlled self-destruction of cells (apoptosis).

Health Conditions Related to Genetic Changes

Monoamine oxidase A deficiency

Mutations in the MAOA gene cause monoamine oxidase A deficiency. This condition affects males almost exclusively and is characterized by mild intellectual disability and behavioral problems, including aggressive and violent outbursts. The mutations reduce monoamine oxidase A activity, causing serotonin and other neurotransmitters to build up in the brain, which may impair an individual's ability to control impulses.

Other disorders

Genetic changes that affect the MAOA gene have been linked to multiple disorders:

  • Deletion mutations: Deletions removing the MAOA and MAOB genes are associated with severely delayed development of mental and motor skills, weak muscle tone (hypotonia), and repetitive hand movements. When the NDP gene is also deleted, individuals may exhibit features of Norrie disease, including blindness, severe intellectual disability, and autism spectrum disorders.
  • MAOA-uVNTR polymorphisms: These common genetic variants affect the gene's activity. "High-activity" alleles produce more monoamine oxidase A protein, while "low-activity" alleles produce less. Low-activity alleles have been associated with an increased risk of aggressive behavior, particularly in individuals who experienced childhood abuse. Conversely, high-activity alleles have been linked to an increased risk of panic disorder in females.

Other Names for This Gene

  • amine oxidase [flavin-containing] A isoform 1
  • amine oxidase [flavin-containing] A isoform 2
  • BRNRS
  • MAO-A
  • monoamine oxidase type A

Frequently Asked Questions

The deficiency leads to excess serotonin and other monoamines in the brain, impairing impulse control. Antipsychotic medications (e.g., risperidone) and mood stabilizers (e.g., valproate) can reduce aggression, but treatment must be individualized and monitored for side effects. Behavioral therapy and structured environments also help.
Such deletions can cause severe motor and mental developmental delays, hypotonia, and repetitive hand movements. Early physical therapy, speech therapy, and developmental monitoring are essential. In some cases, seizures may occur and require neurologic evaluation.
Yes. Since MAOA breaks down tyramine, restricting high‑tyramine foods (aged cheeses, cured meats, fermented products) can prevent tyramine‑induced hypertensive crises and reduce behavioral agitation. A dietitian can create a safe meal plan.
The “high‑activity” allele reduces monoamine levels, which has been linked to lower risk of depression but higher risk of impulsive aggression in some studies. Genetic testing can identify the allele, but environmental factors (stress, upbringing) play a larger role in actual risk.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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