Answer to Question #155204 in Genetics for Ashwani Kumar Gupta

Question

Classic hemophilia is transmitted as a recessive trait linked to the X chromosome.

a) A man with hemophilia married a woman who does not have this disease. They give birth to children without anomalies - a daughter and a son, who remarry with non-hemophiliacs. Will grandchildren find hemophilia and what is the likelihood of sickness in the family of a daughter and son?

b) A man with hemophilia marries a normal woman whose father suffered from hemophilia.

Determine the probability of the birth of healthy children in this family

Answer 1

(a) All the daughters of this man will receive the defective gene carried on his X chromosome. The sons will not suffer from haemophillia since he will give them his Y chromosome.

If the daughter marries a normal man, the man has a normal X, which he will give to his daughters, so no chance of the disease there. The carrier mother (daughter of the hemophiliac man) has one normal gene and one defective gene. This means that 50% of her daughters will be carriers but none of them will be a hemophiliac but 50% of her sons will be hemophiliac.

(b) 2/4 which is 50%