Gene Therapy Successfully Treats Blindness

April 28, 2008 -- Scientists for the first time have used gene therapy to dramatically improve sight in people with a rare form of blindness, a development experts called a major advance for the experimental technique.

Some vision was restored in four of the six young people who got the treatment, teams of researchers in the United States and Britain reported Sunday. Two of the volunteers who could only see hand motions were able to read a few lines of an eye chart within weeks.

"It's a phenomenal breakthrough," said Stephen Rose, chief research officer of the Foundation Fighting Blindness, which helped pay for one study done at Children's Hospital of Philadelphia.

If successful in larger numbers, experts said, the technique has the potential to reverse blindness from other kinds of inherited eye diseases.

"I think this is incredibly exciting," said Dr. Jean Bennett, a professor of ophthalmology at the University of Pennsylvania and a leader of the Philadelphia study. "It's the beginning of a whole new phase of studies."

The research was published online Sunday by the New England Journal of Medicine in conjunction with presentations at a medical meeting in Florida.

The two teams of scientists, working separately, each tested gene replacement therapy in three patients with a form of a rare hereditary eye disease called Leber's congenital amaurosis. There's no treatment for the disease, which appears early in infancy and causes severe vision loss, especially at night.

An estimated 2,000 Americans have the form of the disease they targeted, Bennett said.

Gene therapy -- replacing faulty genes with a normal version -- has been studied in humans for over 15 years with limited success. The field suffered a setback with the 1999 death of Jesse Gelsinger, 18, in an experiment for a liver disorder at Penn. And some children treated for an immune disorder called the "bubble boy disease" later developed leukemia.