The promise of curing genetic diseases by replacing damaged genes with healthy ones is slowly becoming a reality. One recent story is the development of therapy in humans to reverse a form of childhood blindness called Leber congenital amaurosis, or LCA.
OregonLive reports on the story of Alexe Webb who, soon after birth, was diagnosed with LCA the most common cause of inherited blindness in children. Her doctor, Dr. Richard Weleber, said "With this trial, she has the opportunity to have much better vision. We hope the treatment is very durable, that it will last for many decades, even for life."
As detailed at the National Eye Institute web site: “The groundbreaking clinical trials to restore vision in patients with LCA rest on 15 years of basic research with animals. Long before the gene transfer procedure could be tested in people, four critical milestones had to be met: the discovery of the RPE65 gene; creation of a mouse model that illustrates the gene's functions and what happens when it's missing; development of a safe way to carry healthy replacement genes to the target within the eye; and studies of the procedure in a large animal model -- dogs.”
The report continues:
“Dogs carrying a nearly identical mutation to Alexe's were the first test subjects. Within two weeks of treatment, three nearly blind dogs were able to navigate with little problem, Dr. Jean Bennett, a professor of ophthalmology at the University of Pennsylvania Medical School in Philadelphia told the Journal of the American Medical Association in October. The effects of a single injection persisted for more than 10 years in the first dog treated. Researchers learned that retinal cells may be ideal targets for gene therapy because they don't divide much, allowing replaced genes to persist.”