The type of colour blindness are blue, green and red, which is caused by a defect in cone cells. The most usual form is red-green colour blindness (also known as Deuteranopia) affecting 7-10% of males. Red-green colour blindness is an X-linked recessive disorder in which both men and women can get the disease, although it is much more common in males. In order for this disease to occur it requires an affected male and either a homozygous recessive or heterozygous mother. Affected males have normal sons but carrier daughters (or affected daughters depending on the mothers genotype) proving that the disorder is inherited by the X chromosome. Affected heterozygous mothers will pass condition to 50% of daughters and sons. Son's are more likely to inherit the disease as the recessive allele cannot be masked.
- ↑ Reference: Alberts et al (2008) The Molceular Biology of The Cell, 5th Edition. New York: Garland Science.