A man with hypophosphatemia an Xlinked dominant trait causin

A man with hypophosphatemia, an X-linked dominant trait causing low blood P, marries a normal woman. What proportion of their sons will have the condition?

Solution

Hypophosphatemia is a an X-linked dominant trait and is lethal in hemizygous males .since the man with the disease marries a woman who is normal the chances of the son having the disease is zero as he inherits X from his mother.