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Gene injection gives color-blind monkeys normal color vision
by Camilla Abad - September 17, 2009 - comments
Sam and Dalton, two color-blind squirrel monkeys, can now see the colors red and green after gene therapy
September 17, Seattle: Color blind individuals may now have a chance to achieve normal vision after an experiment involving gene therapy cured two color-blind monkeys.
The study, which was published in the journal “Nature” on Wednesday, showed how gene therapy was able to give squirrel monkeys the ability to distinguish the colors red and green. Squirrel monkeys could not see the colors red and green due to a lack of a pigment gene in their eyes, a characteristic similar to color-blind humans.
Gray to blue, yellow, red and green
Jay Neitz, an ophthalmologist from the University of Washington in Seattle, together with his colleagues trained two squirrel monkeys whom they named Sam and Dalton. The monkeys were given vision tests by placing them in front of a screen filled with gray dots that changed color. At the sound of a tone, they touched blue and yellow dots, which earned them a grape juice as a reward.
Sam and Dalton did well on distinguishing the blue and yellow dots but showed frustration when presented with red and green dots.
Virus injection
The initial round of tests was followed by an injection of a virus into the monkeys’ eyes. This virus carries the L-opsin gene, a gene biologically lacking in male squirrel monkeys, which is responsible for color detection.
The same color vision tests were given to the Sam and Dalton after the injection and five months after, researchers noted that the monkeys were then able to pick out the colors red and green repeatedly. Researchers also reported that the monkeys continue to manifest this ability for more than two years.
Implications on humans
The experiment could prove very helpful in treating color-blindness in humans but as Neitz said, “there’s a lot of steps before we actually cure a real blindness in people”.
Bevil Conway, a neuroscientist from the Wellesley College in Massachusetts also explained, "We have no idea if this would work in humans or that it would be a delightful experience for the people post-surgery."
Color-blindness is one of the most common genetic disorders found in humans, especially in males. In the United States, there are an estimated 3.5 million people with this disorder and an estimated 13 million and 16 million in China and India, respectively.