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

• AAAD Disorder
• AADCD Disorder
• DOPA Decarboxylase Deficiency Disorder

What is Aromatic L-Amino Acid Decarboxylase Deficiency Disorder? (Definition/Background Information)

• Aromatic L-Amino Acid Decarboxylase Deficiency (AADC or AAAD) Disorder is a disorder that affects the production of signals that allow cells in the nervous system to communicate with each other
• These signals are called neurotransmitters. When the neurotransmitters are not being produced correctly, there are problems with the nervous system
• Individuals affected by this disorder often have trouble coordinating movements, especially of the head, face, and neck. Other symptoms of the condition include problems controlling blood pressure, heart rate, and body temperature
• AADC Deficiency Disorder is caused by mutations in the DDC gene. The disease is inherited in an autosomal recessive manner
• Diagnosis of the disorder may be established based on a spinal tap and a blood test that show abnormalities in levels of neurotransmitters and enzymes related to the disorder. Genetic testing may be used to confirm the diagnosis
• Treatment of Aromatic L-Amino Acid Decarboxylase Deficiency Disorder may include a variety of medications, which may result in varying levels of success in individual patients. Physical, occupational, and speech therapy may also be of benefit

(Source: Aromatic L-Amino Acid Decarboxylase Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Aromatic L-Amino Acid Decarboxylase Deficiency Disorder? (Age and Sex Distribution)

• Aromatic L-Amino Acid Decarboxylase Deficiency Disorder is a rare congenital disorder. The presentation of symptoms may occur following the birth of the child
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Aromatic L-Amino Acid Decarboxylase Deficiency Disorder? (Predisposing Factors)

• A positive family history may be an important risk factor, since Aromatic L-Amino Acid Decarboxylase Deficiency Disorder is an inherited condition
• Currently, no other risk factors have been clearly identified for AADC Deficiency Disorder

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 Aromatic L-Amino Acid Decarboxylase Deficiency Disorder? (Etiology)

• Aromatic L-Amino Acid Decarboxylase Deficiency Disorder is caused by changes (mutations) in the DDC gene. This gene provides instructions to the body to create an enzyme called the AADC enzyme
• When this enzyme is working properly, it creates neurotransmitters called dopamine and serotonin. These neurotransmitters allow the cells of the nervous system to communicate with each other properly
• When there is a mutation in DDC, the body does not create AADC enzyme correctly, and there are not enough properly working neurotransmitters in the body. These changes therefore cause the symptoms associated with AADC deficiency
• Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency Disorder is inherited in an autosomal recessive manner. This means that both copies of the DDC gene must be changed in order to have symptoms of the disorder. We inherit one copy of each gene from our mother and the other from out father. People with a mutation in only one copy of the DDC gene are known as carriers

(Source: Aromatic L-Amino Acid Decarboxylase DeficiencyDisorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Aromatic L-Amino Acid Decarboxylase Deficiency Disorder?

The signs and symptoms of Aromatic L-Amino Acid Decarboxylase Deficiency Disorder may include:

• Babinski sign
• Choreoathetosis
• Constipation
• Decreased CSF homovanillic acid
• Diarrhea
• Emotional lability
• Feeding difficulties in infancy
• Gastroesophageal reflux
• Hyperhidrosis
• Hyperreflexia
• Hypotension
• Intermittent hypothermia
• Irritability
• Limb dystonia
• Limb hypertonia
• Miosis
• Muscular hypotonia of the trunk
• Myoclonus
• Nasal obstruction
• Ptosis
• Sleep disturbance
• Temperature instability

(Source: Aromatic L-Amino Acid Decarboxylase Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Aromatic L-Amino Acid Decarboxylase Deficiency Disorder Diagnosed?

Aromatic L-Amino Acid Decarboxylase Deficiency Disorder is typically diagnosed based on a number of laboratory tests.

• A spinal tap may be completed to measure levels of substances related to having low levels of dopamine and serotonin
• A blood sample can also be taken to measure the activity of the AADC enzyme
• If these tests are consistent with an individual having AADC Deficiency Disorder, genetic testing can be completed to confirm the diagnosis
• It is recommended that doctors use at least two of these methods to diagnose a person with AADC Deficiency Disorder

(Source: Aromatic L-Amino Acid Decarboxylase Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

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 Aromatic L-Amino Acid Decarboxylase Deficiency Disorder?

The complications of Aromatic L-Amino Acid Decarboxylase Deficiency Disorder may include:

• Malnutrition
• Digestive system abnormalities
• Lack of proper sleep
• Difficulty in moving one’s joints
• Reduced quality of life

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

How is Aromatic L-Amino Acid Decarboxylase Deficiency Disorder Treated?

There is currently no cure for Aromatic L-Amino Acid Decarboxylase Deficiency Disorder. Different medications can be used to help treat the signs and symptoms of the disorder.

• However, although certain combinations of medications may help some people, there is no proven strategy that relieves the symptoms of all people with this disorder
• Whether or a not a treatment works may depend on the exact change in the DDC gene and how much the AADC enzyme is functioning in the body
• Since the nervous system in a child with AADC Deficiency Disorder does not have enough of certain neurotransmitters, the goal of many of the treatments is to make certain as much of these neurotransmitters are available as possible
• Medication could include any one or combination of the following:
  • Dopamine receptor agonists
  • Monoamine oxidase (MAO) inhibitor
  • Pyridoxine (vitamin B6)
• Other treatments may depend on the symptoms of each individual. These treatment options include:
  • Anticholinergic agents to treat movement disorders
  • Seizure medication
  • Gastrointestinal medications
  • Melatonin to treat sleep disturbances
• Physical, occupational, and speech therapy may also be helpful in improving symptoms of the disorder

Gene therapy treatment for AADC Deficiency Disorder seems promising in mice with the disorder (animal models), and clinical studies in humans are currently taking place to learn more about if the treatment is effective and safe.

(Source: Aromatic L-Amino Acid Decarboxylase Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Aromatic L-Amino Acid Decarboxylase Deficiency Disorder be Prevented?

Currently, Aromatic L-Amino Acid Decarboxylase 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 Aromatic L-Amino Acid Decarboxylase Deficiency Disorder? (Outcomes/Resolutions)

There is limited information available about the long-term outlook for people diagnosed with Aromatic L-Amino Acid Decarboxylase (AADC) Deficiency Disorder. There can be a wide variation in the severity of symptoms in people with the disorder.

• It is not expected that the severity of symptoms should increase as an affected individual gets older. However, in some cases new symptoms may develop as side effects to other symptoms
• For example, some people with AADC Deficiency Disorder may develop joint contractures (inability to move joints) due to the movement disorders associated with the disorder
• Some of the symptoms associated with AADC Deficiency Disorder, such as problems controlling the autonomic nervous system, may be life-threatening in moments of stress
• It is important to follow the doctor’s recommendations for monitoring the symptoms of people with AADC Deficiency Disorder and to know what to do in case of an emergency

(Source: Aromatic L-Amino Acid Decarboxylase Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Additional and Relevant Useful Information for Aromatic L-Amino Acid Decarboxylase Deficiency Disorder:

Aromatic L-Amino Acid Decarboxylase Deficiency Disorder is also known by the following names: 

• AADC Deficiency Disorder
• Aromatic Amino Acid Decarboxylase Deficiency Disorder
• DDC Deficiency Disorder

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

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