This research study is for people of any age who have symptoms of weak muscle tone (hypotonia), painful muscle stiffness, uncontrollable movement of the hands and legs, low blood pressure (hypotension), fainting, low blood sugar (hypoglycaemia), impaired sweating, abnormal weight gain, inability to regulate body temperature, vision problems (droopy eyelids and pupil constriction), developmental delay without any clinical or neuroradiological (MRI brain) evidence of cerebral palsy and without a defined cause or set of causes.

The purpose of this study is to learn how many people with cerebral palsy like symptoms, but with no known reason for these symptoms, may actually have a rare genetic condition called Aromatic L-amino Acid Decarboxylase (AADC) deficiency.

Participants will receive diagnostic testing to confirm whether their symptoms, which are consistent with cerebral palsy, may be caused by AADC deficiency. This diagnostic testing, which may include genetic analysis, is conducted through blood testing. This study does not involve any medicines or treatments.

Participants and their families may learn if AADC deficiency is the cause of their neurological symptoms.

This research study is being conducted at multiple locations throughout Europe and the United Kingdom. To see if there is a study location near you, please click here.

What is AADC Deficiency?

AADC deficiency is a rare genetic disorder that affects the brain, causes abnormal muscle tone, and affects how a child develops. AADC deficiency may be the reason for a child's symptoms.

AADC deficiency is very rare, and because the symptoms are similar to symptoms of other conditions, such as cerebral palsy, diagnosis can be difficult.

AADC deficiency is a disorder that interferes with the way the cells in the nervous system talk to each other through substances called neurotransmitters. In AADC deficiency, a genetic mutation (change within a gene) leads to a decrease in the number of neurotransmitters made in the brain.

There is no cure for AADC deficiency, but there are some medicines that doctors use to help treat the symptoms of AADC deficiency.

A person with AADC deficiency may have some or all of the following symptoms. Many of the symptoms of AADC deficiency are similar to cerebral palsy symptoms, and every person is different, so your symptoms or the symptoms of your child may vary.

Some of the most common symptoms of AADC deficiency are:

Low or abnormal muscle tone
Abnormal movements, especially involuntary eye movements*
Delays in development. A child with AADC deficiency may be late in developing or unable to:
Lift and control his or her head
Crawl, sit, or stand without support
Babble or say words

*People with AADC deficiency often have movement problems. These movement problems include involuntary eye movements (called oculogyric crises). These are moments when the eyes suddenly roll upward involuntarily.

What will this study involve?

This research study involves up to two visits to the research centre site and is likely to last approximately 6 weeks

At the first visit, before any study procedures start, the study doctor's staff will describe this study in detail. If you wish (or wish for your child) to participate, you must then sign a document called an Informed Consent Form.

If your child will be the participant, then they may be asked to sign /look at pictures in an Assent Form (depending on their age/ability) while you, as the parent, reads the provided information to your child. This Assent Form should be signed in parallel with the Informed Consent Form for parents/guardians to obtain complete study information.

The study doctor will ask questions about the participant's medical history and then, the doctor's staff will take a finger prick blood sample.

This blood sample will be sent to a lab for testing to see whether there is a particular sign of AADC deficiency in the blood. If no sign is found, the study doctor will inform you of this, and this study will end for that participant.

If a sign of AADC deficiency is found in the first blood sample, the study doctor will ask that the participant return and a second larger blood sample will then be taken. Genetic testing will be performed to see if AADC deficiency can be confirmed. The study doctor will inform you of the results.

Participation Costs

Participants (you or your child) will not receive any payment for taking part in this study.

Participants (you or your child) will not have to pay for the study visits or for the procedures needed to take part.

All reasonable study related travel expenses will be reimbursed from the participant's home address to the local research site and home again, including but not limited to receipts for personal car fuel, train/bus tickets, taxi fares, and parking.

If you think this study may be right for you or your child, please click here to obtain details of the study centre nearest to you. Link to Local Research Site Locations