Colorblindness is one of the most common disorders found in people around the world. Although this disease is not life threatening, it does come as an inconvenience when trying to read and or look at certain materials. Researchers have been studying this disability and may have found a cure for people who have colorblindness. These researches are from The University of Washington in Seattle and also from The University of Florida. Using Squirrel monkeys as the testers for their cure, these researches used gene therapy to cure these monkeys of colorblindness.
Researches are now looking into gene therapy as a cure for colorblindness in humans. Before anything is done, researches have to be sure that this would be a safe procedure to be done on humans. Scientists are looking at the potential for gene therapy to treat adult vision disorders involving cone cells. A cone cell is the photoreceptor cell that is located in the retina of the eye; this cell will function the best in relatively bright light. The retina of the eye is a light sensitive tissue lining the inner surface of the eye. The optics of the eye creates an image of the visual world on the retina, and this serves much of the same function as the film in a camera.
As scientists go further into studying the cure for colorblindness, they have “added a red sensitivity to the cone cells in animals that are born with a condition of colorblindness that is exactly the same as the disability in humans” says William W. Hauswirth; a professor of ophthalmic molecular genetics at the University of Florida college of Medicine and also a member of the UF genetics Institute and the Powell Gene Therapy Center. “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. This is extremely encouraging for the development of therapies for human cone disease that are really blinding.”
This finding is very likely to intrigue the millions of people who face this disability around this world. This includes about 3.5 million people in the United States, more than 13 million in India, and more than 16 million in China. This problem mostly effects men, which leaves about 8% of Caucasian men in the United States incapable of discerning red a green hues that are very important in our everyday life; for instance recognizing traffic light colors. A professor of ophthalmology at the University of Washington said “If we could find a way to do this with complete safety in the human eye, 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.”
This study had been going on for about 10 year; this first started after Neitz and his wife Maureen Neitz, a professor at the University of Washington and also senior author of the study began training two squirrel monkeys named Dalton and Sam. Along with teaching the animals, the Neitz research group also worked with markers of standard vision-testing technique called The Cambridge Colour test to perfect a way that the monkeys could “tell” them which colors that they were seeing. This test is a lot like the tests that school officials are required to give elementary school students at the beginning of each school year; this test allows the children to identify a specific pattern of colored dots among a field of dots that vary in size, color and intensity. To use this test on the monkey, researchers decided to devise a computer touch screen that the monkeys could use to trace the color patterns. When the animals had chosen correctly they were awarded with grape juice.
Researches wanted to produce a substance called long-wavelength opsin in the retinas of the monkeys. The form of the opsin that is found in the retina is a colorless protein that works to make pigments that are sensitive to red and green coloring. While the researches were testing this treatment they used human DNA’s so that they did not have to switch to human genes when they moved toward the clinical treatment said Hauswirth. Hauswirth is also in a clinical trial with human patients to test gene therapy for the treatment of Leber congenital amaurosis, which is a form of colorblindness that often affects children. About five weeks after the monkeys had received this treatment they began to acquire color vision, almost as if it happened overnight.
“Nothing happened during the first 20 weeks”, Neitz said. “But we knew right away when it began to work. It was as if they woke up and saw these new colors. The treated animals unquestionably responded to the colors that had been invisible to them.” It took over a year and a half to test the monkey’s ability to discern 16 hues, which is one of the main properties of color. The two monkeys that are being used for this experiment and research are named Dalton and Sam; these are not just random names given to the monkeys, there is an actual reason as to why they were given these names. Dalton is named after an English chemist named John Dalton who realized he was colorblind and published the first paper about the condition in 1798.
It has now been two years since both of these monkeys have been able to see in color. Continuing to let the monkeys play with the computer and also have their vision checked is part of their enrichment. With this discovery, researches are able to a vision disorder in primates in which all photoreceptors are intact and healthy, and also providing a hint of gene therapy’s full potential to restore vision. 1 in 30,000 Americans have a heredity form of blindness called acromatopsia which causes nearly complete colorblindness and extremely poor central vision. These will be the patients that will be targeted for almost the exact same treatment as the primates. There are still many questions being asked about safety in gene therapy treatment, but it has been done successfully on the primates and it will only be a matter of time until it will be successfully done on human beings.
Sources:
1. NewsRx Health and Science. "University of Florida; Scientists cure color blindness in monkeys." (2009): 198-98. Print.
2. Dell'Amore, Christine. "Color-Blindness cured by gene injection in monkeys." National Geographic. National Geographic News, 16 Sept. 2009. Web.
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