4 ms·

Offtopic, but why is there such a disparity in the percentage of colour blind people between the male and the female population?

by adtac 8y ago

hayksaakian 8y ago
"It is sex-linked: genetic red-green color blindness affects males much more often than females, because the genes for the red and green color receptors are located on the X chromosome, of which males have only one and females have two. Females (XX) are red-green color blind only if both their X chromosomes are defective with a similar deficiency, whereas males (XY) are color blind if their single X chromosome is defective.[12]" via https://en.wikipedia.org/wiki/Color_blindness#Red-green_color_blindness https://en.wikipedia.org/wiki/Color_blindness#Red-green_colo...
- acomjean 8y ago
  Interesting. Because one of the X-chromosomes is inactivated in female cells (which have XX). Otherwise it would lead to over expression of X-chromosome Genes (well most anyway).[1] [1]https://ghr.nlm.nih.gov/chromosome/X https://ghr.nlm.nih.gov/chromosome/X (There are some genetic disorders where an organism have 3 of one chromosome. Trisomy its called.) Which X is inactive is somewhat random however so it seems that it reduces the instance of color blindness.
e98cuenc 8y ago
Color blindness is due to a defective gen that express one of the three kind of cones in the eye. Usually the cones more sensitive to middle length photons (M ~green) become closer to the cones more sensitive to long length photos (L ~red) and thus they can only discriminate colors in between thanks to the other short length cone (S ~blue), but the S cones are almost blind to these colors. The thing is, these genes are in XY chromosome in males, and thus we only have a single copy for each of these genes. Women have two copies of each gene, so even if one goes wrong, the remaining one can express the cones. Funny thing is woman with a defective gen usually just goes unnoticed, but the defective gen in some cases can express a fourth kind of cone with a peak sensitivity between M and L cones, allowing them to perceive colors that usual humans can't perceive.

Offtopic, but why is there such a disparity in the percentage of colour blind people between the male and the female population?

by adtac 8y ago

Offtopic, but why is there such a disparity in the percentage of colour blind people between the male and the female population?

hayksaakian 8y ago

"It is sex-linked: genetic red-green color blindness affects males much more often than females, because the genes for the red and green color receptors are located on the X chromosome, of which males have only one and females have two. Females (XX) are red-green color blind only if both their X chromosomes are defective with a similar deficiency, whereas males (XY) are color blind if their single X chromosome is defective.[12]" via https://en.wikipedia.org/wiki/Color_blindness#Red-green_color_blindness https://en.wikipedia.org/wiki/Color_blindness#Red-green_colo...

acomjean 8y ago
Interesting. Because one of the X-chromosomes is inactivated in female cells (which have XX). Otherwise it would lead to over expression of X-chromosome Genes (well most anyway).[1] [1]https://ghr.nlm.nih.gov/chromosome/X https://ghr.nlm.nih.gov/chromosome/X (There are some genetic disorders where an organism have 3 of one chromosome. Trisomy its called.) Which X is inactive is somewhat random however so it seems that it reduces the instance of color blindness.

e98cuenc 8y ago

Color blindness is due to a defective gen that express one of the three kind of cones in the eye. Usually the cones more sensitive to middle length photons (M ~green) become closer to the cones more sensitive to long length photos (L ~red) and thus they can only discriminate colors in between thanks to the other short length cone (S ~blue), but the S cones are almost blind to these colors. The thing is, these genes are in XY chromosome in males, and thus we only have a single copy for each of these genes. Women have two copies of each gene, so even if one goes wrong, the remaining one can express the cones. Funny thing is woman with a defective gen usually just goes unnoticed, but the defective gen in some cases can express a fourth kind of cone with a peak sensitivity between M and L cones, allowing them to perceive colors that usual humans can't perceive.