The MAOA gene helps make an enzyme that breaks down brain messengers such as serotonin, dopamine, and norepinephrine after they have done their job. This gene plays an important role in mood and impulse control. If it does not work properly, these signals can stay too active, and rare disruptive variants can lead to developmental and behavior changes, including Brunner syndrome. Public attention grew when MAOA was labeled the “warrior gene,” but that nickname oversimplifies the science, and common variants do not define personality or predict violent behavior.
What is a gene?
A gene is a stretch of DNA that holds information cells use to make molecules or regulate processes in the body. Some genes provide the instructions for making proteins, which are the working parts of cells. Other genes mainly control when certain processes happen, where they happen, and how strongly they are carried out. Taken together, genes affect how the body develops and functions, and they can also shape how you respond to food, stress, or medications. For a more detailed look at this topic, you can find more in the LearnHub.
Overview
MAOAGene function
What if the gene works
The MAOA gene helps your body break down brain signaling chemicals, including serotonin, norepinephrine, and dopamine. This helps keep mood, stress response, sleep, and attention more balanced.
Risk
What if the gene does not work
More disruptive variants in the MAOA gene can cause MAOA deficiency, which is linked to impulsive behavior, mood regulation difficulties, and learning or developmental problems. Milder variants may reduce enzyme activity less, so features can vary in timing and severity.
Treatment
What does that mean for your treatment
For loss-of-function or other pathogenic variants in the MAOA gene, no gene-specific treatment or drug-choice guideline is currently established. The MAOA gene is being studied as a drug target and biomarker in psychiatry and some cancers, but this has not led to guideline-based treatment decisions for carriers.
Conditions associated with MAOA
Gene function
What if the gene works
The MAOA gene helps your body clear away certain chemical messengers after they have done their job. This keeps signals in the brain and other tissues from lasting longer than needed. Its everyday cleanup role explains what the MAOA gene does in the brain and body: it helps maintain a more even chemical balance.
The MAOA gene helps cells break down serotonin, norepinephrine, and dopamine after these messengers carry a signal. This cleanup step helps the signal fade at the right time.
By clearing extra monoamines, this gene helps control how strong and how long certain nerve messages last. That supports steady day to day communication in pathways involved in attention, alertness, and stress responses.
MAOA also helps process related amines made during normal body activity and from some foods, including tyramine. This supports chemical balance in tissues such as the brain, gut, and liver.
What is a variant?
A genetic variant is a small difference in the DNA sequence of a gene. These changes are common and are part of normal human diversity, including differences in appearance, metabolism, and how the body responds to environmental influences. Many variants do not have any noticeable effect and simply reflect natural genetic variation. Sometimes, though, a variant can change how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the MAOA gene can change the enzyme’s shape, stability, or amount, which may reduce how well nerve cells clear serotonin, norepinephrine, and dopamine. When looking at how MAOA gene variants affect enzyme activity, milder variants may partly lower activity or expression, while more severe variants can leave little or no working enzyme. That functional range often influences whether MAOA deficiency shows up later and more mildly or earlier with more marked features.
How variants are linked to conditions
Rare, clearly disruptive variants in the MAOA gene cause MAOA deficiency, a rare inherited condition linked to intellectual disability and difficulties with behavior regulation. In contrast, common MAOA variants have been studied in mood, behavior, and mental health risk, but these research associations are inconsistent and do not confirm a diagnosis. This is the key difference between rare MAOA gene variants that cause a condition and common variants that may only influence risk.
A variant is not necessarily a diagnosis
Gene variants are common in the general population and are a normal part of human biology. Most do not have a direct effect on health and instead reflect natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible association rather than a confirmed diagnosis, especially when multiple genes and environmental factors are involved. In other cases, though, a single well-characterized variant in a specific gene can be enough to confirm a diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that clearly increase or reduce health risk related to the MAOA gene. MAOA has been studied in mood and behavior, but these traits are shaped by many genes, life experiences, and environment, so personal concerns are best discussed with a doctor or genetic counselor.
Inheritance of MAOA variants
MAOA gene inheritance for disease-causing variants is usually X linked. The MAOA gene sits on the X chromosome, so a mother carrying a variant can pass it to sons and daughters, while a father passes his X chromosome only to daughters. Males with a pathogenic MAOA variant are more likely to show features because they have one X chromosome, while females may be unaffected or have milder features depending on which copy is active in their cells. This pattern is best established for MAOA-related MAOA deficiency.
What does my MAOA result mean for my family?
For MAOA, family implications are usually discussed in terms of an X-linked pattern. This often means male relatives on the mother’s side could be more likely to have related features, while female relatives may carry the changed gene copy without having the same symptoms. Because of that, close biological relatives may want to review the family history and, if needed, discuss whether the known family result is relevant to them.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a variant in the MAOA gene, genetic testing for MAOA variants looks at DNA from a saliva sample or blood test. A lab reads the gene's sequence and checks for changes, then reports whether a variant was found and if it is known to affect health.
When should I consider getting a genetic test?
For most people, there is not a routine medical reason to test the MAOA gene. Testing may be considered when there is a family history of a very rare inherited MAOA-related condition, especially in boys or men with developmental delays, learning problems, or major behavior changes, together with a doctor or genetic counselor.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but how much it reveals depends on the condition and the type of variant involved. Many factors, including lifestyle, environment, age, and medical history, influence how the body works over time. For some conditions, especially those shaped by many genes, genetic information provides context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result can offer a clear answer. In areas such as medication response, genetic results can also help put individual experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Some people break down or transport a drug differently, so the same treatment may work better for one person, feel too strong for another, or cause more side effects. These differences are common and are one reason medication response can vary from person to person.
What is Pharmacogenetics?
Pharmacogenetics explores how differences in genes shape a person’s response to medication. It examines patterns between genes and drugs to better explain why the same treatment may work differently from one person to another. For many medicines, genes affect both how strongly a drug works and how the body processes it. This information can support more informed, individualized treatment decisions. To look into this topic more closely, you can learn more in the LearnHub.
Drugs influenced by the MAOA gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding routine medication choices, so concerns about side effects, mood changes, or whether a medicine is helping are best discussed with your doctor. MAOA has been studied in research on response to some antidepressants and other medicines that affect brain chemicals, but this is not part of standard prescribing guidance.
History
In the early 1990s, researchers linked the MAOA gene to a Dutch family in which several men shared impulsive behavior and learning difficulties, a condition now known as Brunner syndrome. This was one of the first times a specific gene was tied to a pattern of behavior in people. Building on this early work, scientists studied how MAOA variants might relate to mood, aggression, and stress response in the broader population. Public interest grew in the 2000s when media stories began calling certain MAOA variants the “warrior gene,” a label that oversimplified the science. Over time, descriptions became more precise. Today, the MAOA gene remains an important part of research on behavior, while experts stress that genes act alongside life experiences and environment.