Gene Therapy for Colour Blindness
NatureNews has this story about how two monkeys had their colour vision restored with gene therapy. Here is a brief excerpt:
Neitz and his colleagues introduced the human form of the red-detecting opsin gene into a viral vector, and injected the virus behind the retina of two male squirrel monkeys — one named Dalton in honour of the British chemist, John Dalton, who was the first to describe his own colour blindness in 1794, and the other named Sam....
After 20 weeks, the monkeys' colour skills improved dramatically, indicating that Dalton and Sam had acquired the ability to see in three shades (see video). Both monkeys have retained this skill for more than two years with no apparent side effects, the researchers report in Nature1.
Adding the missing gene was sufficient to restore full colour vision without further rewiring of the brain even though the monkeys had been colour blind since birth. "There is this plasticity still in the brain and it is possible to treat cone defects with gene therapy," says Alexander Smith, a molecular biologist and vision researcher at University College London, who did not contribute to the study.
"It doesn't seem like new neural connections have to be formed," says Komáromy. "You can add an additional cone opsin pigment and the neural circuitry and visual pathways can deal with it."