An animal study has shown gene therapy to be effective even in the later stages of retinitis pigmentosa, which gives hope to more patients of this often inherited condition. This eye disease affects approximately 1 in 4,000 people. Up to 20% of these patients have X-linked retinitis pigmentosa. These individuals, mostly male, have night blindness before they enter puberty, and gradual vision loss by middle age. Around 70% of them have a genetic mutation that prevents the correct production of a protein important for the health of the photo receptors.
The study looked at dogs who naturally
had a similar genetic problem. They used a harmless virus to introduce a corrected gene into the retina of one eye. The other eye, which also had RP, acted as a control.After the treatment, the dogs were tested in a dimly-lit maze and an obstacle course using just one eye (the other was most likely covered). When the treated eye was being used, the animals performed better. An examination revealed better structure of the rods and cones in the eyes treated with the gene therapy. There was improvement regardless of the animals’ stage in the disease.
This type of research indicates that gene therapy for this eye disease may be applicable even to the more advanced cases. This buys patients time while they wait for these therapies to become mainstream.
Study: Beltran WA, Cideciyan AV, et al. “Successful arrest of photoreceptor and vision loss expands the therapeutic window of retinal gene therapy to later stages of disease.” Proceedings of the National Academy of Sciences of the United States of America. E5844–E5853, doi: 10.1073/pnas.1509914112
