Getting your child tested

Learn more about the red flag symptoms that suggest AADC deficiency and the steps required to confirm a suspected diagnosis in this short animation.

AADC deficiency is a very rare inherited disorder. AADC, or aromatic L-amino acid decarboxylase, is an enzyme produced in the human body.

The lack or deficiency of this enzyme affects the body’s production of critical, natural chemicals, called serotonin, dopamine, adrenaline and noradrenaline.

Sometimes, doctors find AADC deficiency hard to recognise because it is reasonably unknown and patients may show symptoms at differing levels.

This means that many affected children can remain undiagnosed, and without an accurate diagnosis, those affected aren’t able to get the support and treatment they need.

Children with AADC deficiency often have symptoms that are similar to more common disorders, such as epilepsy and cerebral palsy.

So, the challenge is: How can doctors obtain an accurate diagnosis? The answer lies in a few symptoms that may set AADC deficiency apart from other conditions…

These symptoms are:

Involuntary eye movements, called oculogyric crises; where the eyes suddenly roll upwards. These episodes can last from a few seconds to hours and can happen several times a day or several times a week
Normal brain scans that aren’t reflective of the symptoms seen in the child
Symptoms associated with bodily functions, such as excessive crying, sweating and drooling
Symptoms that may become worse or more noticeable during the day, but improve with sleep

If a child is showing one or more of these signs and symptoms, they should be tested for AADC deficiency.

To obtain a diagnosis, doctors need to perform multiple evaluations, for example, blood, cerebrospinal fluid and genetic testing. The doctor will explain what kind of sample is needed for each test.

If AADC deficiency is diagnosed, support and treatments can be given, which may help with certain symptoms.

Because AADC deficiency causes many different symptoms, treatment involves different types of healthcare professionals including neurologists, speech therapists, physiotherapists and others.

If you suspect your child has AADC deficiency, ask your child’s doctor for more information about the disorder and testing.

What to expect

If your child has weak muscle tone and delayed development, the doctor may perform a range of tests such as magnetic resonance imaging (MRI) and computed tomography (CT) scans, or an electroencephalogram (EEG) to look for problems in the brain. If these tests do not seem to suggest a specific diagnosis, the doctor may do additional tests. Core tests to diagnose aromatic L-amino acid decarboxylase (AADC) deficiency include:

Lumbar puncture for cerebrospinal fluid (CSF) neurotransmitter metabolite panel

CSF analysis is a diagnostic tool for many conditions affecting the central nervous system. CSF testing is done by collecting some of the fluid from around the spine in a procedure called a lumbar puncture or spinal tap
Blood test for plasma AADC enzyme activity

This test measures the amount of activity of the AADC enzyme, which is reduced in patients with AADC deficiency
Genetic testing

Your child’s doctor may recommend genetic testing to look for a mutation, or change, in the dopa decarboxylase (DDC) gene

Your child’s doctor may also order other tests that will be helpful in diagnosing your child, including blood and urine tests.

What types of doctors can diagnose AADC deficiency?

Paediatric Neurologist

Movement Disorder Specialist

Clinical Geneticist

Listen to our ‘Rare Talks: AADC’ podcast for parents and carers looking to find out more about AADC deficiency. This podcast discusses neurotransmitter diseases, including AADC deficiency, in a way that makes sense to us non-medics
Watch one family’s experience of living with AADC deficiency