As a parent, finding out that your child has a rare genetic disorder like aromatic L-amino acid decarboxylase (AADC) deficiency can be overwhelming.
Here are a few frequently asked questions, with answers and links, to help you learn more about the disorder and what to expect.
What is AADC deficiency?
AADC deficiency is a rare disorder caused by mutations in the DDC gene. The DDC gene contains the instructions necessary for cells to make an enzyme called aromatic L-amino acid decarboxylase (AADC). The body uses this enzyme to make two neurotransmitters: dopamine and serotonin. Neurotransmitters are chemical messengers that transmit signals between nerve cells and other cells. Mutations in the DDC gene mean that the AADC enzyme does not work as it should, resulting in lower levels of dopamine and serotonin that can lead to the symptoms of AADC deficiency.
What symptoms will my child have?
Children with AADC deficiency may develop a number of neurological symptoms, of which the two most common are low muscle tone in the torso and oculogyric crises. Your child may also experience other movement disorders, such as increased muscle tone and contractions, tremors, and abnormal postures.
The disease can also affect the autonomic (involuntary) nervous system. This can lead to such symptoms as low blood pressure, low blood sugar, droopy eyelids (ptosis), excessive sweating or salivation (drooling), changes in body temperature, and possibly sleep disturbances and seizures. Your child may also have nasal congestion, or gastrointestinal issues like constipation or diarrhea.
How common is AADC deficiency?
Researchers don’t know the exact prevalence of AADC deficiency. A few studies have tried to estimate its prevalence in various different countries. One study suggested that AADC deficiency affects 1 in every 32,000 babies in Taiwan. Another gave a “conservative” estimate of the disease, using 2016 figures, affecting 840, 853, and 125 people in the U.S., European Union, and Japan, respectively. A U.S. study found that 36 out of 19,684 people with unknown neurological disorders had mutations associated with AADC deficiency.
How will doctors treat my child?
No cure currently exists for AADC deficiency, so treatment focuses on managing disease symptoms.
Since children with AADC deficiency have low amounts of dopamine, one of the first lines of treatment is either dopamine receptor agonists — medications that activate dopamine receptors — or monoamine oxidase (MAO) inhibitors — medications that prevent the breakdown of dopamine and serotonin.
Forms of vitamin B6 assist the AADC enzyme in its normal activity, so doctors may also prescribe vitamin B6 to boost the activity of any enzymes that the body does produce.
Your doctor may also prescribe additional medications depending on your child’s specific symptoms. For example, they may prescribe melatonin if your child has problems sleeping. They may also prescribe anticholinergics (medications that counteract acetylcholine, the neurotransmitter that causes muscles to contract) to help with rigid muscles, autonomic issues, and oculogyric crises.
Your child might also a feeding tube if they have trouble eating and swallowing their food. The doctor could surgically implant a gastrostomy tube (G tube) into the stomach through your child’s abdomen to allow you to inject food directly.
Will my child have a normal life?
Due to the effects on the nervous system, children with AADC deficiency often experience developmental delays. Activities of daily life, like getting dressed and feeding themselves, can be very difficult. So, your child may be very dependent on you to take care of these activities for them.
Symptoms of AADC deficiency seem to remain fairly constant throughout a patient’s life, but a study of 63 patients indicated that early death due to complications from the disease may be a risk.
How can I find out more about AADC deficiency?
We regularly publish news stories and health insights on our website about AADC deficiency. Other resources also offer information about the disease and its treatments, and can provide support. These include:
- AADC Trust
- National Organization of Rare Diseases (NORD)
- Pediatric Neurotransmitter Disease (PND) Association
- Genetic and Rare Disease (GARD) Information Center
- Metabolic Support UK
Last updated: Oct. 14, 2020
AADC News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
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