A man with hemophilia married a woman whose father had hemophilia.

A man with hemophilia married a woman whose father had hemophilia. What is the genotype of the parents? What generation will be born from such a marriage?

It is generally known that the hemophilia gene (let us designate it as “g”) is a recessive gene and is inherited as part of the X chromosome.

If we designate the chromosome containing the hemophilia gene as Xg, then the chromosome with the gene that is responsible for the well-being in relation to this disease will be designated as XG.

The woman’s father, who, according to the condition, suffered from hemophilia, will be written as Xg Y. He produced two types of sperm – Xg and Y. He passed on a chromosome with a pathological gene – Xg to his daughter.

However, the woman herself does not suffer from the disease in question, therefore, she is heterozygous – XGXg. Her body produces two types of eggs – XG and Xg.

The man with hemophilia who marries her is Xg Y. He, like the woman’s father, produces sperm cells Xg and Y.

The offspring that should be expected from a given married couple are represented by the following options:

healthy heterozygous girls who are carriers of hemophilia (XGXg) – 25%;

healthy homozygous girls (XgXg) – 25%;

boys with hemophilia (Xg Y) – 25%;

healthy boys (XG Y) – 25%.

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