About the AADC Diagnostic Testing Program

Mary Chapman avatar

by Mary Chapman |

Share this article:

Share article via email
cell model

There are only about 100 reported cases of aromatic l-amino acid decarboxylase (AADC) deficiency globally. That’s partly because some patients do not receive the right diagnosis and doctors think they have cerebral palsy or another neurological condition.

To drive the identification of more AADC patients, and to raise awareness about the disease, the pharmaceutical company PTC Therapeutics is offering a free diagnostic testing program.

What is AADC deficiency?

AADC deficiency is a genetic and neurometabolic disease; symptoms usually emerge in early infancy. The cause is a mutation in the DDC gene, which carries the instructions necessary to make the AADC enzyme. This enzyme is crucial for the production of the neurotransmitters dopamine and serotonin from other molecules. When cells cannot make enough functional AADC enzyme because of the mutations in the DDC gene, there isn’t enough dopamine and serotonin. This hinders the ability of nerve cells to communicate with each other and the rest of the body. The disease affects many aspects of a person’s life.

How does the AADC testing program help diagnose patients?

In people with AADC deficiency, L-dopa, the precursor of dopamine, tends to build up in the body. However, this molecule usually is undetectable in the blood. Another molecule, called 3-O-methyldopa (3-OMD), which cells produce when breaking down L-dopa, also tends to accumulate in the blood of AADC deficiency patients. Therefore, measuring 3-OMD blood levels can help identify AADC.

This simple blood test is very different from more invasive AADC diagnostic tests, such as the analysis of the cerebrospinal fluid (the fluid that fills and surrounds the brain and the spinal cord) that has to be obtained through a lumbar puncture (spinal tap).

How does the AADC testing program work?

Healthcare professionals can order the test from PTC Therapeutics if they have concerns about patients who may be showing AADC deficiency symptoms. The test uses Centogene’s dried blood spot collection kit, which the company ships directly to physicians.

If 3-OMD levels are high, doctors will directly measure patients’ AADC enzyme activity. They also will order a genetic test to look for disease-causing mutations in the DDC gene to confirm a diagnosis. Outside the U.S., country-specific rules and restrictions regarding the test may differ.

Why is the AADC testing program important?

For patients and caregivers, the journey to diagnosis can be long and fraught. The sooner an individual receives an accurate diagnosis, the sooner treatments for symptoms can begin.

Identifying the underlying genetic mutations causing AADC deficiency also is critical to understanding the nature and prognosis of an individual patient’s disease. This can bring hope to patients and families.

Where can I get more information?

You may direct your questions regarding diagnostic testing for AADC deficiency to [email protected].


Last updated: July 22, 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 healthcare providers 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.