Promising results have emerged from a gene therapy to “reprogram” cells to reverse the effects of a genetic disorder called AADC deficiency that prevents dopamine formation.
In the study, published in Nature Communications, the researchers developed a gene therapy to alleviate the symptoms of aromatic L-amino acid decarboxylase (AADC) deficiency, a neurodegenerative disorder in children that prevents dopamine and serotonin from being synthesised.
Around 135 children worldwide lack this enzyme in the nervous system, and this affects motor function and emotion. With AADC deficiency, children lack muscle control, speech, and sometimes the ability to hold their heads up. They may also experience prolonged seizure-like episodes.
“Remarkably, these episodes are the first symptom to disappear after gene therapy surgery, and they never return,” says Krystof Bankiewicz, a co-author on the paper and professor of neurological surgery at Ohio State College of Medicine.
“In the months that follow, many patients experience life-changing improvements. Not only do they begin laughing and have improved mood, but many are able to begin speaking and even walking. They are making up for the time they lost during their abnormal development.”
The gene therapy was delivered via a viral vector to seven children between ages 4 and 9 who had AADC deficiency. The benign vector virus had been reprogrammed with specific DNA that could be delivered directly to the brain without viral side-effects. The process was extremely slow so the surgeons could monitor the therapy with real-time MRI, to make sure everything was okay.
“Really, what we’re doing is introducing a different code to the cell and we’re watching the whole thing happen live,” says James “Brad” Elder, director of neurosurgical oncology at Ohio State Wexner Medical Center’s Neurological Institute.
“So we continuously repeat the MRI and we can see the infusion blossom within the desired nucleus.”
The researchers believe that this technique could also be used for other neurodegenerative diseases, such as Alzheimer’s, and clinical trials are underway to test the procedure with other conditions.
Deborah Devis is a science journalist at Cosmos. She has a Bachelor of Liberal Arts and Science (Honours) in biology and philosophy from the University of Sydney, and a PhD in plant molecular genetics from the University of Adelaide.
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