why is colour blindness more common in males than females?

Answer 1

The gene that causes color blindness is located on the same gene that determines a person gender. A female will have to genes that are X shaped. A male will have one X shaped and one Y shaped - it is missing one of the section of the X chromosone.

The gene that causes color blindness is located on the section of the X that is missing from the Y chromosone. So a male who get the color blindness gene has no second X chromosone that may have a non-color blindness gene to block the first one. So the male will be color blind. With a female, if one of the X's is pro-color blindness, she has a 50/50 chance that the other X will block it. So only half as many females will be color blind.

Answer 2

red-green colour blindess is sex-linked i.e. the gene that carries it is on the X-chromosome. Males have only 1 copy of the X-chromosome, inherited from their mothers, so any genetic fault will be expressed.

Females have two X-chromosomes and if either one of them carries the functional copy of the gene then this will 'override' the faulty copy on the other chromosome. Females will only suffer the condition if both chromosomes carry the non-functional gene.

If the frequency of the red-green colourblind allele is 0.1 then this is the likelihood that a male will be colourblind, however the chance for a female is only 0.01 (0.1 x 0.1) so you can see that there can be big differences in the numbers of male and female sufferers.

Answer 3

Color blindness, or color vision deficiency, in humans is the inability to perceive differences between some or all colors that other people can distinguish.
There are many types of color blindness. The most common are hereditary (genetic) photoreceptor disorders, but it is also possible to acquire color blindness through damage to the retina, optic nerve, or higher brain areas, or due to exposure to certain chemicals.

Color vision deficiencies can be classified as acquired or inherited/congenital. There are three types of inherited or congenital color vision deficiencies: monochromacy, dichromacy, and anomalous trichromacy.

Dichromacy is a moderately severe color vision defect in which one of the three basic color mechanisms is absent or not functioning. It is hereditary and sex-linked, as it is a recessive disease linked to the X-chromosome, and affects predominantly males (12 percent of men and about 0.2 percent of women).

It is also called Daltonism, because was first described by John Dalton, a British chemist and physicist, in the 19th century.

Interesting tests at this site:

http://home.wanadoo.nl/paulschils/05.03.html

Answer 4

Colour blindness is carried by our X chromosomes. So men have only one X chromosomes where as women have 2 X chromosomes. Colour blindness is recessive towards noncolour blindness. Men have only 1 X chromosome so when they have a colour blindness chromosome he will be colour blind. Where as women have 2 X chromosomes so they need to have 2 colour blindness chromosomes to be colour blind.

Answer 5

Color blindness is a sex linked trait meaning and the alleles for this trait are on the X chromosome. Normal Women have 2 X chromosomes and Normal Men have an X chromosome and Y chromosome. Females are red-green color blind only if both their X chromosomes have alleles for the defect, whereas Men are color blind if their "only" X chromosome has alleles that represent the trait.

Answer 6

it is so because the gene for colour blindness is in recessive state hence cannot show its expression in presence of other X chromosome but in case of male X character are dominant over those in Y hence it expresses itself. it is visible in female only in homozygous condition

Answer 7

Evolution. Because it's just not necessary for men to know all those shades of lipstick and all those girly colours like mauve and taupe and beige so over time Mother Nature has taken that part of a man's brain and used for really useful stuff like changing spark plugs and making the towels filthy when they have, allegedly, 'washed their hands' afterwards.

Answer 8

not sure why more males have it than females but both my sons have colour deficiency and the optician said it was unusual for 2 siblings to have it

Answer 9

This is a sex linked recessive disease carried on the x chromosome. A woman would only have it if both parents gave her a defective x and she xx defective.

Answer 10

just a theory - is one of the genes responsible on the X chromosome?? cause men only have one so their X faults will be expressed (same reasoning as why there are only male haemophiliacs)