A healthy man and a healthy woman have a son with Lesch-Nyhan syndrome,an X-linked recessive trait.What are the chances that a daughter of this couple will inherit Lesch-Nyhan syndrome?

Question

Quizplus · Accepted Answer

Lesch-Nyhan syndrome is an X-linked recessive disorder. Since the son has the syndrome, he must have inherited the affected X chromosome from his mother, who is a carrier. The father, being healthy, has a normal X chromosome. For a daughter to have the syndrome, she would need to inherit the affected X chromosome from both parents. However, the father can only pass on a normal X chromosome, so the daughter cannot inherit the syndrome.

A Healthy Man and a Healthy Woman Have a Son