A man with AB blood type who suffers from color blindness marries a girl with normal vision and blood type O

A man with AB blood type who suffers from color blindness marries a girl with normal vision and blood type O. The girl’s father is color blind and has blood type A. Two children were born from this marriage: a girl with normal vision and blood type A and a boy with normal vision and blood group B. Make a pedigree of this family, indicate the genotypes of all family members. What is the likelihood of these people being colorblind? Can children be born with parental blood types?

It is well known that the gene for color blindness is inherited in the X – chromosome and is recessive.

Let’s designate the gene that causes the development of color blindness in humans as d. The gene that determines well-being in this vision pathology will be designated as D.

The chromosome containing the abnormal gene will be written as X d. The chromosome with the normal vision gene will be labeled X D, respectively.

The father of a woman with color blindness has one X – chromosome, therefore, having the genotype X d Y IA I0, he transfers to his daughter with I blood group (genotype I0 I0) a chromosome with a pathological gene and a recessive allele of blood group – X d I0.

Thus, a healthy woman has the genotype X D X d I0I0. It produces two types of oocytes – X D I0, X d I0.

The man with whom she marries has the genotype X d Y IA IB and produces sperm cells X d IA, X d IB, Y IA, Y IB.

The offspring of this married couple are represented by the following options:

healthy girls with blood of group II (X D X d IAI0) – 12.5%;

healthy girls with blood of the III group (X D X d IBI0) – 12.5%;

healthy boys with blood of group II (X D Y IAI0) – 12.5%;

healthy boys with blood of the III group (X D Y IBI0) – 12.5%;

girls with color blindness and blood of group II (X d X d IAI0) – 12.5%;

girls with color blindness and blood of the III group (X d X d IBI0) – 12.5%;

boys with color blindness and blood of group II (X d Y IAI0) – 12.5%;

boys with color blindness and blood of the III group (X d Y IBI0) – 12.5%.

Answer: the probability of having children with color blindness is 50%; children with parental blood groups (I and IV) cannot be born in this family.