The recessive gene for color blindness is localized in the x-chromosome.

The recessive gene for color blindness is localized in the x-chromosome. A color-blind woman married a man with normal color vision, what is the likelihood of being color-blind.

Let’s designate the chromosome with which the gene responsible for the development of color blindness is linked as “Xd”, then the sex chromosome responsible for the development of normal color discrimination will look like “XD”.

A man who normally distinguishes colors will have a set of XDY chromosomes and produce sperm XD and Y. A woman is color blind – Xd Xd, produce eggs: Xd.

Possible options for the offspring of this pair:

healthy girls XDXd (50%);

boys are color blind XdY (50%).

Answer: The probability of having a child with color blindness in this couple is 50% (all boys).