PTC Opens Online Resource to Help Doctors Diagnose AADC Deficiency

A new online resource, called AADC Insights, aims to make it easier for healthcare professionals to diagnose and care for people with aromatic l-amino acid decarboxylase (AADC) deficiency.

AADC deficiency is an extremely rare condition caused by mutations in the DDC gene, resulting in a lack of a working AADC enzyme. This enzyme is important for the production of dopamine and serotonin, two neurotransmitters (brain signaling molecules) that are critical for normal brain function.

The lack of functional AADC enzyme — and consequent lack of dopamine and serotonin — lead to symptoms such as decreased muscle tone, developmental delay, and movement disorders, most notably oculogyric crisis (involuntary upward eye movement).

Symptoms of AADC deficiency usually appear in the first few months of life — the average age at symptom onset is 2.7 months. However, diagnostic delays are frequent, and the average age at AADC diagnosis is 3.5 years.

Part of the reason for this gap is the rarity of the condition: less than 120 people worldwide have been diagnosed with AADC deficiency, and many healthcare professionals are unaware of signs and symptoms that might lead to them to suspect it.

AADC Insights offers doctors and other professionals information that aims to make diagnosing AADC deficiency easier. For example, the site offers a description of common disease symptoms, and a diagnostic checklist of tests that should be performed to detect AADC deficiency.

It also includes tips for differential diagnosis — that is, for distinguishing between AADC deficiency and other conditions, like certain forms of epilepsy, that may have similar clinical features.

And it provides interactive clinical cases, letting healthcare professionals practice making diagnoses based on certain available data.

Beyond diagnostic information, AADC Insights offers a variety of other resources, including an interview with a patient’s caregiver, interviews and insights from experts in AADC deficiency, tips for managing the disease, and information on recent relevant scientific studies.

The site is organized and funded by PTC Therapeutics, which is developing a single-dose gene therapy to potentially treat AADC deficiency, called PTC-AADC.

The company recently shared news of the first two AADC deficiency patients in Europe — both living in France – having been treated with this investigational gene therapy under an early access program.

An application seeking approval for PTC-AADC to treat patients in the European Union is currently being reviewed. Responses have been given to European Medicines Agency questions based on that application, and PTC expects an opinion from the agency’s Committee for Medicinal Products for Human Use in the coming months, it reported in a financial update.

PTC is also on track to file a similar approval request with the U.S. Food and Drug Administration by mid-year, it announced in a separate financial report.