Question

A woman with an x-linked dominant disorder mates with a phenotypically normal male. on average, what percentage of this couple's daughters will be affected with the disorder?
a. 100%
b. 75%
c. 50%
d. 25%
e. 0%

Answer 1

E. 0%

X-linked dominant disorders are not very common in females because it has to be on BOTH of their alleles in order to occur phenotypically.

Because you get one chromosome from your mom and another one from your dad, it would be impossible for the daughter to get the disorder because the dad doesn’t have it on his X chromosome to pass on to her.

In the case of the daughter, the focus is whether or not the dad has the disorder, the mom isn’t as relevant. However, if you were talking about a son, it would be a different story.

Hope this helps :)