The mutation stops the development of the color-sensitive cells in the human retina, and people with the latent gene cannot distinguish particular colors. It is called color blindness. John Dalton described human color blindness. It is called Daltonism. 95% of color blind people are red-green color blind. There is no cure for color blindness or people who are color blind are never cured. The best test for color blindness is the Ishihara color test.