Monoamine Oxidase A Deficiency: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Monoamine Oxidase A Deficiency?
A primary care doctor is often the first stop and can coordinate care, usually referring the patient to specialists such as a medical geneticist, psychiatrist, neurologist, or behavioral therapist. Direct primary care and concierge doctors, who charge flat or membership fees instead of billing insurance, can spend extra time managing this condition and coordinating specialist care.
What it is
Monoamine oxidase A deficiency is a rare genetic condition passed down in families through changes in a gene. The gene gives the body instructions for making an enzyme that breaks down certain brain chemicals. When it is missing or does not work well, those chemicals can build up.
Symptoms
The most described signs involve behavior and mood. People with this condition may act aggressively or impulsively, and some have trouble controlling anger. Others may show repetitive actions or trouble with social communication, which can look like autism spectrum disorder. Other possible signs include trouble sleeping and unusual body movements.
Causes and who gets it
This condition is caused by a change, also called a mutation, in the MAOA gene, which sits on the X chromosome. Boys have only one X chromosome, so a single changed copy is enough to cause the condition. Girls usually carry the change without strong symptoms. A mother who carries the changed gene has a 50 percent chance of passing it to each son.
How doctors diagnose it
Diagnosis often starts with a detailed history of behavior and development. Doctors may order lab tests, including a urine test that measures certain chemicals. Genetic testing can confirm the diagnosis by finding a change in the MAOA gene. A genetic counselor can explain what results mean for a family.
Treatment
Care focuses on managing symptoms. Behavioral therapy can help with aggression and impulse control, and doctors may prescribe medicines that affect mood or behavior. This requires care because some medicines can build up to unsafe levels when the enzyme is not working. Regular follow-up helps track how symptoms change over time.
When to see a doctor
Talk to a doctor if a child shows ongoing aggressive behavior, extreme impulsivity, or other behavioral concerns that do not improve. Seek help right away if there is any risk of harm to the child or to others. Adults who learn that a family member has this condition may want to ask about genetic testing and counseling.
Common questions
Is monoamine oxidase A deficiency the same as being prone to violence?
No. The condition has been linked to impulsive and aggressive behavior in some people. It does not mean a person will be violent. Environment, upbringing, and support all play a role. People with the same gene change can have very different outcomes.
Can women have this condition?
Women can carry the changed gene, but they usually do not have strong symptoms. This is because they have a second, working copy of the gene. Some carriers have mild signs. A genetic counselor can explain what this means for a specific family.
Can it be cured?
There is no cure. Treatment aims to manage symptoms through behavioral support and careful use of medicines. Results differ from person to person.
Why do some medicines need to be avoided?
The missing enzyme normally breaks down certain drugs in the body. Without it, those drugs can build up to unsafe levels. This is why every doctor should know about the diagnosis before prescribing anything new.
Sources
- MedlinePlus Genetics - Monoamine oxidase A deficiency
- NIH Genetic and Rare Diseases Information Center - Brunner syndrome
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
