September 23, 2008

Gene Therapy Improves Vision

Better vision thanks to an experimental gene therapy, was announced by U.S. researchers on Monday.

Three patients in their 20's reported markedly better vision after getting the treatment, according to Artur Cideciyan and James Wilson of the University of Pennsylvania.

"Day vision improvement could range up to 50-fold from pre-treatment levels. Night vision was quite dramatic and ranged up to 63,000 times" better, said Cideciyan.

The report was published in the Proceedings of the National Academy of Sciences.

It supports similar results from rival teams all treating the same condition known as Leber congenital amaurosis, or LCA.

LCA damages light receptors in the retina; it affects sight in early childhood and causes total blindness by the time a patient is 30. Currently, there is no treatment.

The condition is caused by a mutation in a gene called RPE65, and experts say it is a worthy target for gene therapy.

Gene therapy is an experimental field of medicine that aims to correct diseases by replacing faulty genes.

"We checked whether it was day or night vision or both that was restored by this therapy," Cideciyan said. "We found that both are corrected or restored in this condition."

"The patients are saying, 'There is a difference in my vision -- things are looking brighter. The colors are more vivid and I am seeing colors,'" he added.

He noted the patients were not entirely blind. "It's like ... wearing three deep dark sunglasses on top of each other," he said. "What our treatment does is it basically removes two of the three (pairs of) sunglasses in one part of eye."

The effects have lasted for as long as three months, Cideciyan said.

Two other teams reported similar results in the New England Journal of Medicine in April.

The improvements were confined to the specific area of the eye where the new genes were injected, said Cideciyan.

"There are many steps to go," he said.

He said its tough to treat the entire retina. In LCA, some of the photoreceptor cells are completely destroyed.

"The key question is how much and where the remaining photoreceptors are in the eye," Cideciyan said.

A handful of the researchers own equity in a company called AGTC Inc that might commercialize some aspects of this work.

Wilson, a gene therapy pioneer, has licensed patents related to gene therapy to a number of biopharmaceutical companies.


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