If ongoing studies in dogs go well, the researchers said, the first human studies could begin in three to four years. But that said, it's hard not to get very excited about this, because it's a very dramatic result. I mean, basically these dogs were blind, and now they are not blind anymore. Children with Leber congenital amaurosis have little or no vision at birth, and what little they may have is lost over time. It occurs when there is a defect in any of several genes that help convert light into electrical signals in the eye.
Parents carrying the defect on one copy of the gene have normal vision.
The condition affects children who inherit a defective copy from each parent. Mutations in any of a dozen or so other genes also cause the disease, and mutations in scores of others genes cause other forms of retinitis pigmentosa. Jean Bennett, Maguire's wife and co-worker, led the new study, in which thousands of viruses were injected directly into the eyes of three blind Briard puppies. The viruses had been genetically engineered by scientists at the University of Florida to contain healthy versions of the rpe65 gene, which the viruses then delivered to the dogs' retinal cells. But the right eyes got injections directly behind the retina, very close to the so-called retinal pigment epithelial cells where the rpe gene does its job.