Congenital red–green color blindness

Congenital red–green color blindness is an inherited condition that is the root cause of the majority of cases of color blindness. It has no significant symptoms aside from its minor to moderate effect on color vision. It is caused by variation in the functionality of the red and/or green opsin proteins, which are the photosensitive pigment in the cone cells of the retina, which mediate color vision. Males are more likely to inherit red–green color blindness than females, because the genes for the relevant opsins are on the X chromosome. Screening for congenital red–green color blindness is typically performed with the Ishihara or similar color vision test. There is no cure for color blindness. This form of colorblindness is sometimes referred to historically as daltonism after John Dalton, who had congenital red–green color blindness and was the first to scientifically study it. In other languages, daltonism is still used to describe red–green color blindness, but may also refer colloquially to color blindness in general. Color blindness The only significant symptom of congenital red–green color blindness is deficient color vision (color blindness or discromatopsia). Additionally, approximately __% of colorblindness is caused by congenital red–green colorblindness, so the condition and symptom are often difficult to untangle. A red–green color blind subject will have decreased (or no) color discrimination along the red–green axis. This commonly includes the following colors of confusion: Cyan and Grey Rose-Pink and Grey Blue and Purple Yellow and Neon Green Red, Green, Orange, Brown Black and Red (protans) Congenital red–green color blindness is classified into 1 of 4 groups: Protanopia Protanomaly Deuteranopia Deuteranomaly Each of these groups comprises a prefix and a suffix. The prefix indicates the cone (photopsin) that is affected, with lexemes from Greek, "first" (prot-) or "second" (deuter-) referring to the L- and M-opsins respectively.