When will the red-green color blindness cure be ready for humans?

While gene therapy has successfully allowed red-green color-blind monkeys to see new colors that they have never seen before, we still don’t know what their internal perceptions of those colors are like, or if any psychological side-effects might result from humans suddenly being able to see a new dimension of color. [Note: There have been no indications of psychological distress in the monkeys.] Gene therapy also involves risks associated with the viral vector and therapeutic transgene being injected, and with the surgical procedure itself (subretinal injection). Therefore, the first step in moving the treatment forward will be determining its safety for use in human patients.

Human experiments involving gene therapy must first be reviewed and approved by the National Institute of Health’s (NIH) Office of Recombinant DNA Activities (ORDA)/ Recombinant DNA Advisory Committee (RAC) and by the Food and Drug Administration (FDA). In addition to approval of an Investigational New Drug Application (IND) from the FDA, approval from an Institutional Review Board (IRB) where the study will take place must also be obtained.

We would also need to recruit subjects who would be willing to be pioneers in the cure for red-green color blindness; that is, willing to accept the risks involved knowing that it may not work.

The same gene therapy virus vector and injection procedures are currently being used in human gene therapy trials for a blinding disorder known as Leber’s congenital amaurosis, or LCA. Thus far, no serious adverse events have been reported, even after one year post-treatment. A key difference in our experiments for color blindness is the therapeutic gene that is carried by the virus vector. Because a human visual pigment gene was used to replace the missing visual pigment of the monkeys, and no adverse side effects have been observed, we are optimistic that this transgene will also be safe to use in humans. The most critical barrier in moving the treatment forward will be insuring its safety for human patients.

While red-green color blindness is generally not considered to be a debilitating visual disorder, many affected individuals would disagree. Normal color vision is required for employment as a police officer, fire fighter, commercial/public transit driver, or pilot. In other professions, the requirement for normal color vision is not as obvious, and some spend years training for careers as designers, geologists, chemists, or ophthalmologists before being excluded by their color vision deficiency. Everyday difficulties associated with red-green color blindness are presented in the slide show, “colorblind world.”