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Gene Therapy Cures Color Blindness in Monkeys--Wider Applications Seen

Researchers have successfully used gene therapy to cure red-green color blindness in adult squirrel monkeys. Red-green color blindness is the most common single locus genetic disorder in humans. One in 12 men and 1 in 230 women are affected, while 1 in 6 women is a carrier of the inherited condition. “We’ve added red sensitivity to cone cells in animals that are born with a condition that is exactly like human color blindness," said Dr. William W. Hauswirth, an author of the study. “Although color blindness is only moderately life-altering, we’ve shown we can cure a cone disease in a primate, and that it can be done very safely. That’s extremely encouraging for the development of therapies for human cone diseases that really are blinding.” “People who are colorblind feel that they are missing out,” said Dr. Jay Neitz, one of the senior authors of the study. “If we could find a way to do this with complete safety in human eyes, as we did with monkeys, I think there would be a lot of people who would want it. Beyond that, we hope this technology will be useful in correcting lots of different vision disorders.” In this work, the researchers wanted to produce a substance called long-wavelength opsin in the retinas of the monkeys. This particular form of opsin is a colorless protein that works in the retina to make pigments that are sensitive to red and green. “We used human DNAs, so we won’t have to switch to human genes as we move toward clinical treatments,” said Dr. Hauswirth, who is also involved in a clinical trial with human patients to test gene therapy for the treatment of Leber congenital amaurosis, a form of blindness that strikes children. Of further note is the fact that approximately 1 in 30,000 Americans has a hereditary disease called achromatopsia, which causes nearly complete color blindness and extremely poor central vision. “Those patients would be targets for almost exactly the same treatment,” Dr. Hauswirth said. Even in common types of blindness such as age-related macular degeneration and diabetic retinopathy, vision could potentially be rescued by targeting cone cells, he said. This work was reported on September 16 in the online edition of Nature. [Press release 1] [Press release 2] [Nature abstract]