Suppose that a man and woman have a son with a rare genetic disorder known to be X-linked. There is no occurrence of the disorder on the woman's side of the family, but the man's brother has it, as does her father. What is the probability that the son's defective allele came from the man?

Question

Quizplus · Accepted Answer

The disorder is X-linked, meaning it is carried on the X chromosome. Since the son is male, he inherits his X chromosome from his mother and his Y chromosome from his father. Therefore, the defective allele must have come from the mother, not the father.

Suppose That a Man and Woman Have a Son with a Rare