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Official Full Name
monoamine oxidase A
This gene encodes monoamine oxidase A, an enzyme that degrades amine neurotransmitters, such as dopamine, norepinephrine, and serotonin. The protein localizes to the mitochondrial outer membrane. The gene is adjacent to a related gene on the opposite strand of chromosome X. Mutation in this gene results in monoamine oxidase deficiency, or Brunner syndrome.
MAOA; monoamine oxidase A; amine oxidase [flavin-containing] A; Amine oxidase [flavin containing] A; AOFA_HUMAN; EC; flavin containingA; HGNC:6833; MAO A; MAO-A; Monoamine oxidase type A; RP1 201D17_B.2

Brief Introduction

Monoamine oxidase A (MAOA), encoded by MAOA gene, can degrade monoamine neurotransmitters such as norepinephrine, dopamine, and serotonin. The human MAOA gene is located in the p11.23-11.4 region of the X chromosome and consists of 15 exons. There is a 30 bp variable tandem repeat polymorphism (MAOA-u VNTR) at 1.2 kb upstream of the promoter region of the MAOA gene. The polymorphism is composed of 6 alleles, namely 2R, 3R, 3.5R, 4R, 5R and 6R. Related studies have shown that 3.5R and 4R are high activity alleles, while 2R and 3R are low activity alleles.

There is a 30 bp variable tandem repeat (30 bp VNTR) site in the promoter region of MAOA gene. The polymorphism at this site is related to the activity of MAOA, as well as the susceptibility to mental illness. The 30 bp VNTR site of MAOA gene is an important functional site affecting the activity of MAOA. Individuals carrying the 3R sequence are 2-10 times less efficient at converting monoamines than individuals carrying the 4R sequence. A large number of studies have found that 4R allele carriers are highly susceptible to mental illness, and these individuals are prone to mental illness such as depression, autism, and suicide.

MAOA Gene and Depression

The occurrence of depression has an important genetic basis. Early quantitative behavioral genetics studies have indicated that genetic factors can account for 24%~55% of depression variation. In recent years, with the development of molecular genetic technology, people have conducted in-depth research on the pathogenesis of depression. MAOA gene is one of the important candidate genes for genetic research in depression. The MAOA gene plays an important role in the metabolism of 5-hydroxytryptamine, norepinephrine and dopamine neurotransmitters associated with depression. Moreover, psychopharmacological evidence also shows that monoamine oxidase inhibitors are classical antidepressants. However, there are still some differences in the study of human subjects.

MAOA Gene and Suicidal Behavior

MAOA is expressed on the mitochondrial outer membrane and presynaptic membrane, mainly degrading serotonin (5-HT), norepinephrine (NE) and deamination. Changes in the structure and function of MAOA can lead to changes in the level of 5-HT, thus affecting the individual’s emotional and psychological state, which in turn have an impact on their behavior. Most studies have shown that MAOA plays an important role in controlling aggression and impulsiveness. The abnormal transcriptional activity of MAOA enhances the individual's response to stress, exhibits strong impulsive and aggressive behavior, and eventually leads to suicidal behavior.


  1. Liu Yangyang, et al. Advances in MAOA-VNTR gene polymorphism and suicidal behavior [J]. Injury Medicine (electronic version), 2017, (4).
  2. Liu Limin, et al. The interaction between MAOA gene and environment on antisocial behavior and its possible brain mechanism [J]. Progress in Psychological Science, 2017, (6).
  3. Hu Xia, et al. Advances in biogenetics and environmental factors of adolescent antisocial personality disorder [J]. School Health, 2016, (2).
  4. Korean Navy, et al. The relationship between MAOA gene and creativity tendency [J]. Journal of Henan University of Science and Technology (Medical Edition), 2015, (3).

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