A hemophilic man married a healthy woman whose father had hemophilia.

A hemophilic man married a healthy woman whose father had hemophilia. what percentage of these parents’ children may have hemophilia?

The hemophilia gene is linked to the X chromosome.

The woman is healthy, but her father suffered from hemophilia (had the XhY genotype). The female genotype always contains two X chromosomes, one of which, associated with a recessive trait, she inherited from a sick father, and the second, with a dominant trait, from a healthy mother. The woman’s genotype looks like XHXh, that is, the woman is heterozygous for hemophilia. This woman’s husband has hemophilia. He, like the woman’s father, has the XhY genotype.

The woman forms gametes of two types: XH and Xh

A man forms gametes of two types: Y and Xh

Variants of offspring genotypes: XHXh, XhY, XHY

Since the probability of having boys and girls is 50% to 50%, the following conclusions can be drawn:

all girls born to this couple will be healthy (and this is 50% of the offspring).

The probability of having a boy with a recessive hemophilia gene is also 50% to 50%, which means that the probability of having a healthy boy is 25%,

and, finally, the sought-for probability of having a boy with hemophilia is 25%.