For the first time, scientists have successfully used gene therapy to treat a rare form of inherited blindness called Leber's congenital amaurosis (LCA)(先天性黒内症). The disease’s progression is related to the mutation of a gene that produces proteins needed by the retina. After researchers injected copies of a working version of the defective(欠陥のある)gene into the eyes of the test subjects, a number of them showed marked improvements in their vision. Incredibly, within weeks of undergoing the procedure, two of the LCA patients who had previously suffered such severe vision loss that they could only see hand motions had improved enough to read a few lines of an eye chart.