US scientists report they have successfully used gene therapy to restore sight to animals with a rare inherited form of blindness.
A team of scientists led by Jean Bennett, at the University of Pennsylvania, reported their success in this month's Nature Genetics.Their experiment involved dogs with Leber congenital amaurosis (LCA), a form of blindness, that also affects human infants and for which there is no treatment.
The disease involves a defect in the genes responsible for the retina's ability to translate light into nerve impulses. In humans, LCA causes severe rapid onset of blindness, a process which begins before birth so infants are born partially blind.
Bennett's team injected the eyeballs of dogs born with LCA with cells modified to contain the appropriate functional genes which restored the animals' sight.Humans are next"This is a dog model of a human disease," said Dr Jonathon Stone of Sydney University who studies the environmental factors contributing to blindness. "It's impressive that the researchers have shown such a degree of improvement in sight - a several fold increase."
However, Dr Stone told ABC Science Online that applying this work to humans would not be immediate nor straightforward."In the dog, LCA shows a slow progression and so the researchers were able to work with adult dogs," he said. "In humans, any gene therapy would have to occur before birth".
Dr Stone said a further challenge would be identifying the exact genetic defect for LCA.
"Different people with LCA have defects in different genes, or different parts of the same gene, and this varies from one continent to another," he said. He was confident, nevertheless, that geneticists could achieve this.