Four people with a rare inherited condition which leads to blindness in childhood have reportedly experienced improved vision after taking part in the world's first trials of an experimental gene therapy, according to two independent studies published online in the New England Journal of Medicine. Professor Robin Ali, who led the team based at University College London, UK, said: 'This trial establishes proof of principle of gene therapy for inherited retinal disease and paves the way for the development of gene therapy approaches for a broad range of eye disorders'. Ali's success has been mirrored by another group led by Jean Bennet at the University of Pennsylvania, US.
The volunteers were all affected by a form of inherited blindness called Leber Congenital Syndrome (LCS), which causes progressive deterioration in vision and can lead to blindness in teenagers. Each participant underwent a complex operation, during which a harmless virus, injected into the retina at the back of the eye, delivered working copies of the defective gene into the cells.
For the first time since having the treatment, all three of the patients who took part in Bennett's trial could see better in dim light, read the first three lines on an eye chart and navigate easily around a specially designed maze. So far only the youngest of Ali's three participants - an 18-year-old called Steven Horwath - has yet to show significant improvement, a result which Ali believes may be due to the progression of the disease. 'Steven had the best preserved retina - that almost explains why he had the best results', he told the Daily Telegraph.
Although these results are promising, it will be some time before gene therapy becomes widely available for the treatment of inherited retinal diseases, stressed Ali. 'While we're very excited about the improvement in Steven's vision, it's important to emphasise that gene therapy is still an experimental treatment not yet generally available to patients', he said.
Both groups plan to test the therapy on younger patients, potentially moving onto other forms of retinal disease in the near future.