LCA is one of several incurable forms of blindness collectively known as retinitis pigmentosa. Doctors said they suspect that similar gene therapy treatments could prove curative for many of the 150,000 Americans suffering from that broad family of diseases, all of which involve a deterioration of the light-detecting retina in the back of the eye. If current studies in dogs go well, the researchers said, the first human studies could begin in the next three to four years. Children with LCA have little or no vision at birth, and what little might be there is lost over time. The affliction is the result of 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 two defective copies, one from each parent. Mutations in any of a dozen or so other genes also cause LCA, 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 Briards. 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' ailing retinal cells. The dogs' left eyes got injections into one part of the eye an area distant from the retina with no effect.