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 on 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 on 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, for which there is no treatment. The early results of the eye experiments should give the field a boost, some experts said.
"I think it's really a big shot in the arm for gene therapy and for medicine in general," said Dr. Ronald Crystal, head of genetic medicine at Weill Cornell Medical College in New York.
Each of the study participants had mutations in a gene that makes a protein needed by the retina, which senses light and sends images to the brain. Those without the gene gradually lose sight until they are blind in early adulthood.
The retina itself stays in relatively good shape for a while, making it a good candidate for gene therapy, said Robin Ali, a professor at University College London, who led the British team. He likened the defective gene to a missing spark plug in a car engine.
"The whole engine can be absolutely fine, but if it doesn't have a spark plug, the car's not going to work," said Ali.
For the experiment, the scientists injected millions of copies of a working gene beneath the retina in the back of the eye. Only one eye was treated - the worst one - in case anything went wrong; the untreated eye was used for comparison. After the treatment, their eyesight and light sensitivity were measured periodically; mobility was tested in a maze or an obstacle course.
All three of those treated in Philadelphia showed significant improvement in their vision, the researchers said.
In the British group, the treatment only worked in 18-year-old Steven Howarth, whose disease was less advanced than the other two - a girl, 17; and a man, 23.
Leber's congenital amaurosis：利伯氏先天性黑内障