Monoamine oxidase A deficiency is a rare disorder that occurs almost exclusively in males. It is characterized by mild intellectual disability and behavioral problems beginning in early childhood.

Monoamine oxidase A deficiency is caused by mutations in the MAOA gene. This gene provides instructions for making an enzyme called monoamine oxidase A. This enzyme breaks down chemicals called monoamines, including serotonin, epinephrine, and norepinephrine. These particular monoamines act as neurotransmitters, which transmit signals between nerve cells in the brain. Monoamine oxidase A helps break down the neurotransmitters when signaling is no longer needed. Signals transmitted by serotonin regulate mood, emotion, sleep, and appetite. Epinephrine and norepinephrine control the body's response to stress. Monoamine oxidase A also helps break down monoamines found in the diet.

Monoamine oxidase A deficiency is thought to be very rare. Its prevalence is unknown.

This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Published Date: May 01, 2017
Published By: National Institutes of Health