Colorblindness describes mild to severe difficulties with identifying various colors and shades of colors. Individuals who suffer colorblindness may tend to confuse some colors, and a rare few may not see colors at all. Color blindness can be acquired as a genetic defect or result from a chronic illness (e.g., Alzheimer's disease, diabetes, glaucoma, leukemia, liver diseases, chronic alcoholism, macular degeneration, multiple sclerosis, Parkinson's disease, sickle cell anemia, and retinitis pigmentosa), or trauma (i.e., accidents or strokes that damage the eye). Most cases of color blindness are inherited, affecting males almost exclusively.

Color blindness is found as a X-linked recessive trait. Linked to the X chromosome, such traits can pass passed from grandfather through in intermediate female carrier. Because females have two X chromosomes (XX genotype), the disease is rare in females. Males, having only one X chromosome (part of the XY set of sex chromosomes...