October 26, 2009

Gene Therapy Restores Eyesight To Children

Scientists have announced the success of a single gene injection that can cure retinal disease.

Writing in The Lancet on Saturday, doctors claim that a single gene therapy injection successfully reverses the effects of congenital blindness by producing light-sensitive pigments in the back of the eye.

The treatment is being used to heal children with an inherited disease known as Leber congenital amaurosis (LCA), which typically results in complete blindness by the age of 40.

"This result is an exciting one for the entire field of gene therapy," said Dr. Katherine A. High, co-first author of the study and the director of the Center for Cellular and Molecular Therapeutics.

"All 12 patients given gene therapy in one eye showed improvement in retinal function," High said.

The therapy has proven to be successful for nine-year-old Corey Haas, who is now able to enjoy simple childhood activities because he can now see better than ever before.

"Before, I used to ride my bike just in front of the house and now I just ride around the neighborhood with no one watching," Haas told reporters.

Researchers studied the therapy in 12 volunteers, ages eight to 44 years.

"This study reports dramatic results in restoring vision to patients who previously had no options for treatment," said High.

"These findings may expedite development of gene therapy for more common retinal diseases, such as age-related macular degeneration."

Scientists developed a modified virus that is injected directly into the eye to deliver the proper DNA to the diseased retina.

The study was initially intended to ensure that the gene therapy injection was safe, but it delivered promising results.

Although none of the patients reported having normal eyesight after treatment, each of them saw at least a 100-fold increase in pupillary light response.

What's more, six of the 12 participants reported improved eyesight to levels that meant they no longer would be classified as legally blind.

"The clinical benefits have persisted for nearly two years since the first subjects were treated with injections of therapeutic genes into their retinas," said senior author Dr Jean Bennett, Kirby professor of Ophthalmology at the University of Pennsylvania School of Medicine.

"These remarkable results have laid a foundation for applying gene therapy not only to other forms of childhood-onset retinal disease, but also to more common retinal degenerations," Bennett added.


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