A man with color blindness – color blind (a sign of sex-linked) – marries a woman – a carrier of color blindness.

A man with color blindness – color blind (a sign of sex-linked) – marries a woman – a carrier of color blindness. Can a normal son be expected in this marriage? A daughter with color blindness?

As you know, the gene of the pathology under consideration is inherited in the structure of the X chromosome.

Let’s designate the gene that causes the development of color blindness in humans as d. The gene that determines the development of the ability to adequately identify different colors is denoted as D.

The chromosome with the gene for color blindness will be X d, and the chromosome with the gene for normal color detection will be X D.

A male with color blindness will have the X d Y genotype. His body will produce two types of sperm – X d and Y.

A woman who is a healthy carrier of the gene for color blindness has the XD X d genotype and is capable of producing two types of eggs – X D and X d.

The offspring possible for a given married couple include the following options:

girls with color blindness (X d X d) – 25%;

heterozygous girls with color discrimination rate (X D X d) – 25%;

boys with color discrimination rate (X D Y) – 25%;

boys with color blindness (X d Y) – 25%.

Answer: in the marriage of these persons, one can expect the birth of a healthy son with a probability of 25%, a daughter with color blindness – with a probability of 25%.