Color+Blindness

by Colin, Bryan, Noam



Nature of the Genetic Difficulty
Color blindness is a genetic disorder that makes it hard to tell the difference between certain colors. When you are color blind, it usually does not mean you see everything in black and white or shades of grey. That type of color blindness almost never occurs. Most color blind people have trouble with just 1 or 2 colors. The colors they have the most difficulty telling the difference between are red and green. You see in color because the retina (at the back of the eye) has special cells called cones. These detect color for the brain, but in color blind cases these cones do not work properly and colors are jumbled up. Color blindness is usually an inherited and lifelong condition. It is most commonly passed from mother to son. A woman can be a “carrier” of the gene, but will usually not be color blind herself. If a man has the color blindness gene then he is color blind. The gene for color blindness is located on the X chromosome. The X chromosome is sex chromosome. It is a recessive trait, so for women to get it the have to be homozygous recessive. But men have only one X chromosome so if their mother is a carrier then they might receive the trait. For that reason, men are more commonly color blind than women.



Basis Facts of Disease
People can't see colors. It actually relatively simple. Usually nothing needs to be done. Your child may find that some tasks are frustrating such as: • coloring with markers or crayons • matching clothes • reading color-coded maps or weather charts • knowing if fruits are ripe or if meat is rare or well-done In some cases, a color blind person may need to avoid careers that require excellent color vision. 

Prognosis
Prevalence of color blindness Men Women Total References Overall — — — Overall (United States) — — — Red-green (Overall) 7 to 10% — — [24][25] Red-green (Caucasians) 8% — — [26] Red-green (Asians) 5% — — [26] Red-green (Africans) 4% — — [26] Monochromacy — — — Rod monochromacy (dysfunctional, abnormally shaped or no cones) 0.00001% 0.00001% — [27] Dichromacy 2.4% 0.03% 1.30% [24][27] Protanopia (red deficient: L-cone absent) 1% to 1.3% 0.02% — [24][27] Deuteranopia (green deficient: M-cone absent) 1% to 1.2% 0.01% — [24][27] Tritanopia (blue deficient: S-cone absent) 0.001% 0.03% — [27] Anomalous Trichromacy 6.3% 0.37% — [27] Protanomaly (red deficient: L-cone defect) 1.3% 0.02% — [27] Deuteranomaly (green deficient: M-cone defect) 5.0% 0.35% — [27] Tritanomaly (blue deficient: S-cone defect) 0.01% 0.01% — So based upon the graph above, color blindness ails predominantly white males. How is it diagnosed? An eye doctor can do a very simple test for color blindness. Your child can look at a special test book that has a pattern of small colored circles. Some of the circles on the page are a different color and form a number. A color blind child will not be able to see the number because it will appear as the same color as the other circles on the page. The test book has about a dozen of these patterns in it to make sure of the diagnosis and to judge the severity of the color blindness. 

Sources Cited
[|James, Andrew. “Color Blindness”] [|Davenport, Paula. “Weight on their Minds”.]