Color blindness transmitted through

(A) X-linked recessive # COLOR BLINDNESS> Gross cases occur in 3%--4% of males, but are rare in females (0.4%); milder cases are more common in males.> Colour blindness is an inherited condition, being transmitted as X-linked recessive through the female who is usually unaffected, and is probably due to the absence of one of the photo-pigments normally found in the foveal cones.> In most cases reds and greens are confused, so that the defect is a source of danger in certain occupations, such as in engine- drivers and sailors. The red-green cases fail into two chief groups, protanopes and deuteranopes.