As children, most of the 1.5 million people worldwide who have retinitis pigmentosa start to lose the ability to see at night. As they get older, cells in their retina further degenerate, giving them tunnel vision; by the time they reach adulthood, many are legally blind. Retinitis pigmentosa is caused by an inherited genetic mutation that causes the retina to degrade over time. 90 percent of retinitis pigmentosa cases are caused by a single mutation on a gene called RGPR. The researchers hypothesized that, if they could insert functional cells without the mutation into patients’ retinas, they could slow—or even eliminate—the retina’s decaying function. But for that to work, they would need functional retina cells that wouldn’t be attacked by the immune system if they were implanted. To
Retinitis Pigmentosa
