Experimental Gene Therapy Found To Slow Huntington's Disease Progression

Doctors report the first successful treatment for Huntington's disease using a new type of gene therapy given during 12 to 18 hours of delicate brain surgery. The BBC reports: An emotional research team became tearful as they described how data shows the disease was slowed by 75% in patients. It means the decline you would normally expect in one year would take four years after treatment, giving patients decades of 'good quality life', Prof Sarah Tabrizi told BBC News. The first symptoms of Huntington's disease tend to appear in your 30s or 40s and is normally fatal within two decades -- opening the possibility that earlier treatment could prevent symptoms from ever emerging. None of the patients who have been treated are being identified, but one was medically retired and has returned to work. Others in the trial are still walking despite being expected to need a wheelchair. Treatment is likely to be very expensive. However, this is a moment of real hope in a disease that hits people in their prime and devastates families.

It starts with a safe virus that has been altered to contain a specially designed sequence of DNA. This is infused deep into the brain using real-time MRI scanning to guide a microcatheter to two brain regions - the caudate nucleus and the putamen. This takes 12 to 18 hours of neurosurgery. The virus then acts like a microscopic postman -- delivering the new piece of DNA inside brain cells, where it becomes active. This turns the neurons into a factory for making the therapy to avert their own death. The cells produce a small fragment of genetic material (called microRNA) that is designed to intercept and disable the instructions (called messenger RNA) being sent from the cells' DNA for building mutant huntingtin. This results in lower levels of mutant huntingtin in the brain.

The data showed that three years after surgery there was an average 75% slowing of the disease based on a measure which combines cognition, motor function and the ability to manage in daily life. The data also shows the treatment is saving brain cells. Levels of neurofilaments in spinal fluid -- a clear sign of brain cells dying -- should have increased by a third if the disease continued to progress, but was actually lower than at the start of the trial.

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