A type of muscular dystrophy shows sex- linked recessive inheritance. Affected persons usually die by the age of 20. Suppose that a boy with the disease lives long enough to marry a woman heterozygous for the trait. If they have a son, what is the probability that he will have the disease?

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Quizplus · Accepted Answer

The disease is sex-linked recessive, meaning it is carried on the X chromosome. The affected father (X^dY) will pass his Y chromosome to his son, and the heterozygous mother (X^DX^d) has a 50% chance of passing the X^d chromosome. Thus, the probability the son will have the disease is 50%.

A Type of Muscular Dystrophy Shows Sex- Linked Recessive Inheritance