Clinical Trials and AADC Deficiency

Emily Malcolm, PhD avatar

by Emily Malcolm, PhD |

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There have been only about 100 cases of aromatic L-amino acid decarboxylase (AADC) deficiency described in the medical literature. It is very difficult to develop effective treatments when the patient population is so small. But one way patients can help with research into new treatments is to participate in clinical trials. In this way, patients also gain access to new treatments under development, long before they are available commercially.

What are clinical trials?

Clinical trials are part of the approval process for new treatments. In a clinical trial, researchers test a medication, device, or other intervention to determine if it is safe and effective. Researchers also use clinical trials to determine if a new treatment is better than what is already available to patients.

Throughout the trial, the physicians and researchers record the symptoms that patients experience in order to determine what side effects the treatment may have.

In the U.S., the structure of a clinical trial has to be approved by the U.S. Food and Drug Administration (FDA) before it begins. To get that approval, researchers usually have to test the treatment in an animal model or laboratory first to show it is safe and effective. If these preliminary experiments go well, the FDA may approve a clinical trial in people.

What are the advantages of participating?

If your child participates in a clinical trial, you normally don’t have to pay for the medications they take during the trial. Usually the clinical trial also covers the participants’ medical care. The trial also may compensate patients for their time and cover costs such as travel to and from the trial site.

What are some potential disadvantages?

Depending on how the trial is designed, not everyone participating receives the experimental treatment.

In a double-blind study, the researchers randomly assign patients to receive either the experimental treatment, or standard care, or a placebo. In this type of trial, neither the researchers nor the patients know which group they are in, so the data is not biased and the researchers can determine whether the experimental treatment actually has an effect and to what extent.

In open-label clinical trials, both patients and physicians know which treatment patients are receiving throughout the study.

Another potential downside of clinical trials is that the new treatment is experimental. So, it may have side effects that can be serious. Until several clinical trials are complete, the researchers may not know what side effects a certain treatment may cause. In rare cases, side effects can be serious enough that patients have to withdraw from the trial.

Is my child eligible for a clinical trial?

Talk to the doctor or healthcare team managing your child’s disease. Your doctor can help you determine eligibility for a clinical trial. They also may be able to offer insight about the likelihood of the experimental treatment working. Finally, they may help you with necessary testing prior to beginning the trial.

A current list of AADC deficiency clinical trials that are recruiting or preparing to recruit participants is available on the National Institutes of Health (NIH) Library website.


Last updated: May 26, 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.