"In truth, we did not expect to see such dramatic improvements

This has huge implications for anyone with a genetic retinal disease such as age-related macular degeneration or retinitis pigmentosa because it has, for the first time, shown, that gene therapy can be applied safely before the onset of vision loss.

The trial was carried out on patients suffering from choroideremia a rare inherited cause of blindness which affects around 1 in 50,000 people.

It is caused by a defective gene which fails to produce REP-1 a protein needed to keep pigment cells in the retina healthy. Without it the cells slowly stop working, switch off and die.

The first symptom of the condition is usually poor night vision which can occur in early childhood. Later, the field of vision progressively narrows to a "tunnel" until only a small central slit remains.

The purpose of our trial is to put this missing protein back into the retinal cells and prevent further degeneration, said Prof MacLaren.

We're not talking about treatment that needs to be repeated we're talking about a single one off replacement of the gene.

What was unique and exciting is we noticed visual improvements very early, which shows us that it is working.

"If we were able to treat people early, get them in their teens or late childhood, we'd be getting the virus in before their vision is lost. If the treatment works, we would be able to prevent them from going blind."

The scientists found that the protein could be replaced in the eye by inserting it into the DNA of a harmless virus which can be injected into cells beneath the retina. As the virus infects these retinal cells the missing protein is restored.

Continued here:
Gene therapy heralds cure for blindness

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