The promise of gene therapy has finally made a breakthrough. A rare, deadly brain disease, found in young boys, known as adrenoleukodystrophy (ALD) has been shown to have positive results with patients after receiving gene therapy.

About one in 21,000 boys are born with ALD–a genetic defect found on the X chromosome. This defect prevents cells from making a special protein that the cells need to process certain fats. Without that protein, the fats begin to build up and eventually destroy myelin that protects nerves in the brain, destroying important connection and basically ‘crushing the brain.’ The disease is very rare among females, since their second X chromosome will override the other defective one, so both X chromosomes must be defective for a female to receive the disease.

Currently, the only approved treatment for ALD is a bone marrow transplant. The transplant allows white blood cells from the marrow go to the brain and turn into glial cells that produce the necessary ALD proteins. However, bone marrow transplants have many risks, including immune rejection and so on. Finding matching donors can be a struggle (especially for rare blood types such as ‘O Negative’ blood).

Sponsored by the biotech company Bluebird Bio, scientists removed blood cells from 17 boys with cerebral ALD, their age ranged from 4 to 13 years old. The scientists then treated the cells with modified- hence harmless- HIV viruses, so it would ‘carry’ the necessary ALD protein gene. They then reinfused the cells back into the patients. Within 6 months, 16 patients stabilized. In brain scans taken up to 2 years later, most of the boys showed no further signs of inflammation or loss of myelin. 16 of the 17 had no signs of neurological decline such as vision loss or trouble walking.

Now the effects of ALD aren’t reversed with gene therapy, so the boys aren’t completely healthy. Especially those who weren’t treated at earlier ages. And the disease can still progress in the few months after the treatment, while the modified cells ‘get settled’ into their new task. But the boys are in school and living normal lives. And this only the beginning, with such an amazing breakthrough with gene therapy, imagine the possibilities to come.