Researchers Say Gene Therapy Shows Promise for Treating Retinitis Pigmentosa

Researchers are reporting good news for people with Retinitis Pigmentosa, a genetic degenerative eye disease that affects thousands of Americans, and for which there is no cure. But as Houston Public Radio's Jim Bell reports, several areas of research are showing promise.

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People usually learn they have Retinitis Pigmentosa in their teenage years. They lose their night vision and much of their peripheral vision in their thirties, and most will be legally blind in their 50s. It's incurable, but researchers at the University of Florida are using gene therapy to shut down the gene that causes one type of Retinitis Pigmentosa, but only in laboratory mice. Doctor Stephen Daiger of the University of Texas Health Science Center says this treatment is close to clinical trials.

"By being able to understand the exact genetic cause in a given individual, it's possible to design a replacement for the defective gene, for the gene that causes the problem, and at least in several animal models, in that particular form of retinal disease, in those animals when the defective gene is replaced the animals don't go blind. They retain their vision."

Dr. Daiger says researchers are also finding promise in what are called "young" stem cells.

"There is some evidence that a stem cell from a very early newborn mouse retina, for example, may be able to replace a defective retinal cell in an older animal that has retinal disease."

Dr. Daiger says they've also close to testing a small time release capsule that's implanted in the diseased eye, where it releases chemicals that slow the progression of the disease. All this promising research is good news for Mary Kathryn LeMaster of Victoria. She was 13 when she learned she has RP. She's 33 now. She can still move around on her own, and even drive her car, but only in the daytime.

"I have never driven at night. I do drive during the day. As time has gone on I definitely am having more problems where I have to scan rooms a lot more than normal. My peripheral (vision) has definitely gotten worse."

Mary Kathryn says her slow vision loss has forced her to make some adjustments in how she lives and gets around.

"You know, going out when you're in your twenties you need help if you're gonna go to a bar or go to any kind of function at night, and I've had to call on my friends a lot. And I've been really blessed with my friends and family, that they've been able to help me get around, and also it's opened their eyes to a different life style."

Mary Kathryn is married and she wants children, even though she knows her children will have the gene that's causing her to go blind. She says she plans to volunteer for clinical trials on all those promising treatments out there on the horizon, because by the time her children start showing signs of RP, it's entirely possible it will be curable. Jim Bell, Houston Public Radio News.