Gene Therapy Could Potentially Halt Blindness in Choroideremia

In a recent study, researchers found that a gene therapy technique that injects a virus into the eye of a patient with choroideremia caused significant improvement in vision for up to 4 years.

This process delivers billions of healthy genes that replace the gene in their retina missing in these patients.

This treatment was administered to 6 patients with choroideremia, which causes blindness. These patients were followed for 4 years in a study published in the New England Journal of Medicine.

Researchers found that 2 patients showed significant improvement for at least 4 years. Another 3 patients were able to maintain their vision in their treated eyes, but 1 patient who received a lower dose had a slow decline in vision in both eyes.

Researchers said that since this gene therapy is expected to be long lasting, it would be applied early in the disease.

"Gene therapy is a new technique in medicine that has great potential. As we learn more about genetics we realize that correcting faulty genes even before a disease starts may be the most effective treatment. Gene therapy uses the infectious properties of a virus to insert DNA into a cell, but the virial DNA is removed and replaced with DNA that is reprogrammed in the lab to correct whichever gene is faulty in the patient,” said lead researcher Robert MacLaren, MB, ChB, DPhil, FRCOphth, FRCS, VR. "In this case, success in getting a treatment effect that lasts at least several years was achieved because the viral DNA had an optimal design and the viral vector was delivered into the correct place, using advanced surgical techniques. In brief, this is the breakthrough we have all been waiting for."

Many of the patients said they never expected the be able to read without straining their eyes and have found they are happier and venture outside more often, according to the study.

"To permanently restore sight to people with inherited blindness would be a remarkable medical achievement,” Stephen Caddick, PhD, GRSC, BSc, director of innovation at the Wellcome Trust concluded. "This is the first time we've seen what appears to be a permanent change in vision after just one round of treatment. It's a real step forwards towards an era where gene therapy is part of routine care for these patients."