A couple have a son who has haemophilia A. They are concerned about any future children they might have. What is the likelihood that they would have a daughter who also has haemophilia A?

Question

Quizplus · Accepted Answer

Haemophilia A is an X-linked recessive disorder. For a daughter to have haemophilia A, she must inherit the affected X chromosome from both parents. Since the father cannot pass an affected X chromosome to his daughter (he passes his Y chromosome instead), it is impossible for them to have a daughter with haemophilia A under normal circumstances.

A Couple Have a Son Who Has Haemophilia A