Gene Therapy Proves Effective in Treating AADC Deficiency in Trial

According to the publication over the weekend from San Francisco CBS affiliate KPIX, a groundbreaking clinical trial for those with aromatic l-amino acid decadboxylase (AADC) deficiency was undertaken at UCSF Benioff Children’s Hospital in San Francisco.

About AADC Deficiency

AADC deficiency is a rare inherited genetic disorder. Scientist believe a mutated version of the DDC (dopa-decarboxylase) gene is responsible for the development of the condition. This gene is responsible for coding the production of the eponymous enzyme AADC, which plays in important role in the manufacture of important neurotransmitters such as dopamine and serotonin.

AADC deficiency is typically diagnosed with in the first year of life. Symptoms can include severe delays in speech and mobility milestones. Children born with AADC deficiency might have difficulty moving at all – some describe their lack of muscle tone as being Jell-O-like. However, on the reverse side of the issue, patients may also experience episodes of intense involuntary movement called oculogyric crises. These oculogyric crises can be characterized by pain, muscle spasms, involuntary motion of the head and eyes, and intense emotional irritation. Patients with aggressive forms of the condition usually die before reaching seven years of age due to extensive physical complications.

This is an incredibly rare condition. Even as a someone who spends much of his time writing about rare diseases, I cannot stress this enough. AADC deficiency has only been described in global medical literature about 100 times ever. The chances of you for someone you love being born with a DC deficiency is almost nil.

About the Clinical Study

Because AADC deficiency is such a rare condition, clinical expertise is limited. Before recent advances, little if any treatment existed to improve the quality of life of these afflicted individuals.

The new study was led by UCSF neurologist Dr. Krystoph Bankiewicz. He and his team use a technique called gene therapy to treat the condition. Gene therapy uses thousands of otherwise harmless, inert viruses to deliver functioning copies of the associated malfunctioning DDC gene to the patient’s brain. Scientists use deactivated viruses to deliver the new genetic material because viruses are amazingly small; they can easily permeate the super-selective blood-brain barrier that keeps most typical drugs out of the brain (where often they need to go).

The team observed an acute improvement in the condition of their six patients after flooding certain areas of their brains with these genetically-modified viruses. All six of the children brought in for the trial on can now sit up and lift their head under their own power, and reports of their uncomfortable oculogyric crises have slowed to a standstill. All of the kids sleep better too, doubtlessly as well as their parents.

Hopefully, in the years to come, this experimental procedure will become more commonplace in treating AADC deficiency.


What advantages might there be to developing a cure for a condition that has only affected about 100 people ever? Do you think it will help with other research? Share your thoughts with Patient Worthy.

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