Gene-Transfer Proves Safe for Vision Problem

FRIDAY Sept. 12, 2008 -- Three people with a rare, incurable form of hereditary blindness regained some sight after receiving experimental gene therapy, a new report says.

The patients, all in their early 20s, have Leber congenital amaurosis type 2 (LCA2), a disease in which photoreceptor cells cannot respond to light, because a gene called RPE65 does not properly produce a protein necessary for healthy vision.

In the study, published online in Human Gene Therapy, researchers at the University of Florida used an adeno-associated virus. an apparently harmless virus that already exists in most people. to deliver RPE65 to a small area of the retina.

The subjects said the vision in their treated eyes was slightly improved in dim lighting conditions.

"The patients report seeing brighter areas and perhaps some images, but basically the message is that this treatment is fully safe," William W. Hauswirth, a professor of ophthalmology and member of the university's Powell Gene Therapy Center, said in a news release issued by the university.

No ill effects, other than routine post-surgical soreness, were reported.

"The study has partially restored vision in three young adults, and it demonstrates that gene therapy can be effective in treating human vision disease," Dr. Paul A. Sieving, director of the National Eye Institute, which supported the experiment, said in the same news release. "Many human diseases are inherited in families and result from mutations in single genes. These genetic conditions are particularly suited to potential treatment by gene therapy. This trial to treat vision loss from the condition of Leber congenital amaurosis is an important demonstration of proof of principle and shows that we are on the right track. We can now invest in further work to refine, and ultimately to expand, genetic treatment approaches."

A detailed examination of the therapy's effectiveness in the treated portion of the eye was expected to be published in an upcoming issue of the Proceedings of the National Academy of Sciences.

LCA2 affects about 2,000 people in the United States and is one of several incurable forms of blindness collectively known as retinitis pigmentosa, which in turn affects about 200,000 Americans.

More information

The Prevent Blindness America has more about retinitis pigmentosa .

Posted: September 2008


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