In humans, hemophilia is caused by a recessive gene linked to the x chromosome. A healthy woman whose father

In humans, hemophilia is caused by a recessive gene linked to the x chromosome. A healthy woman whose father was hemofelic married a healthy man whose father suffered from hemophilia What is the probability of having healthy children and children suffering from hemophilia?

Let’s designate the chromosome that carries the gene that causes the development of hemophilia as Xh, then the chromosome that leads to the development of a normal human blood coagulation system will be designated as XH.

The father of the woman getting married was hemophilic – XhY, he produced sperm cells Xh and Y. He passed on the chromosome responsible for the development of the female to his daughter. It contained a pathological gene. Since the woman is healthy, therefore, she is heterozygous – XH Xh. It produces germ cells, both containing the hemophilia gene and those containing the normal coagulation gene – XH and Xh.

The man’s father, like the woman’s father, is XhY, but he only transfers Y to his son, therefore, if the man is healthy, he is written as XH Y, and produces sperm cells that do not carry pathological genes – XH and Y.

The probable offspring of this family are represented by the following options:

male children with normal blood clotting (XH Y) – 25%;

male children with hemophilia (XhY) – 25%;

female children – a carrier of a pathological gene, with normal blood clotting (XHXh) – 25%;

female children with normal blood clotting (XHXH) – 25%.

Answer: the probability of giving birth to children with hemophilia in this couple is 25%, the probability of having healthy children is 75%.