What are the other Names for this Condition? (Also known as/Synonyms)

• Brunner Syndrome
• Deficiency Disorder of Monoamine Oxidase A
• X-Linked Monoamine Oxidase Deficiency Disorder

What is Monoamine Oxidase A Deficiency Disorder? (Definition/Background Information)

• Monoamine Oxidase A Deficiency Disorder is a rare condition that is characterized by mild intellectual disability and behavioral difficulties (including aggressive and sometimes violent behaviors and autistic features)
• Affected people may also experience night terrors, tremor, stereotypical hand movements, and/or occasional body twitches. Signs and symptoms generally develop in childhood and the condition is seen almost exclusively in males
• Monoamine Oxidase A Deficiency Disorder is caused by changes (mutations) in the MAOA gene and is inherited in an X-linked recessive manner
• Treatment is based on the signs and symptoms present in each person. Some recent studies suggest that cautious treatment with certain medications (called selective serotonin reuptake inhibitors) and dietary modifications can improve symptoms

(Source: Monoamine Oxidase A Deficiency; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Monoamine Oxidase A Deficiency Disorder? (Age and Sex Distribution)

• Monoamine Oxidase A Deficiency Disorder is an extremely rare inherited condition. Its exact prevalence is not known at the present time
• The onset of disease symptoms typically occurs in childhood
• The condition predominantly affects males

What are the Risk Factors for Monoamine Oxidase A Deficiency Disorder? (Predisposing Factors)

• A positive family history may be an important risk factor, since Monoamine Oxidase A Deficiency Disorder can be inherited
• Currently, no other risk factors have been clearly identified for this condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Monoamine Oxidase A Deficiency Disorder? (Etiology)

• Monoamine Oxidase A Deficiency Disorder is caused by mutation(s) in the MAOA gene
• This gene codes for the enzyme monoamine oxidase A, which catalyzes the breakdown of chemicals known as monoamines. Examples of such chemicals include neurotransmitters in the brain (serotonin, epinephrine and norepinephrine)
• A deficiency in this enzyme leads to build-up of such chemicals throughout the body
• The condition is inherited in an X-linked recessive manner

X-linked recessive pattern of inheritance: 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.

What are the Signs and Symptoms of Monoamine Oxidase A Deficiency Disorder?

The signs and symptoms of Monoamine Oxidase A Deficiency Disorder may include:

• Aggressive behavior            
• Autism
• Night terrors
• Tremors
• Stereotypical hand movements
• Body twitches (rare)

Based on the frequency of symptoms observed, the following information may be noted:

• Very frequently present symptoms in 80-99% of the cases:
  • Behavioral abnormality            
  • Cognitive impairment
• Occasionally present symptoms in 5-29% of the cases include motor delay.

(Source: Monoamine Oxidase A Deficiency; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Monoamine Oxidase A Deficiency Disorder Diagnosed?

Monoamine Oxidase A Deficiency Disorder is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary
• Molecular genetic testing to check for or confirm causative gene mutation(s)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Monoamine Oxidase A Deficiency Disorder?

The complications of Monoamine Oxidase A Deficiency Disorder may include:

• Violent behavior
• Learning disability
• Anxiety and panic

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Monoamine Oxidase A Deficiency Disorder Treated?

There is no cure for Monoamine Oxidase A Deficiency Disorder, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can Monoamine Oxidase A Deficiency Disorder be Prevented?

Currently, Monoamine Oxidase A Deficiency Disorder may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Monoamine Oxidase A Deficiency Disorder? (Outcomes/Resolutions)

• The prognosis of Monoamine Oxidase A Deficiency Disorder is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Monoamine Oxidase A Deficiency Disorder:

Research findings imply that mistreatment in childhood may play a role in increasing the severity of the signs and symptoms of Monoamine Oxidase A Deficiency Disorder and consequent behavioral problems.

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/