Question

Duchenne muscular dystrophy is an X-linked recessive disorder. If a man with this disease has children with a woman who is homozygous dominant for this allele, what percentage of their offspring would be expected to have the disease phenotype?

Answer 1

None of their daughters will have the disease, but they will all be carriers. There is a 50% chance that each of their sons will have the disease phenotype.

Step-by-step explanation:

In this case, Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder. Since the man has the disease, he will pass the DMD allele to all of his daughters. However, since the woman is homozygous dominant for this allele, she will not have the disease, and she will not pass the disease allele to any of her children.

Therefore, none of their daughters will have the disease, but they will all be carriers of the disease. On the other hand, there is a 50% chance that each of their sons will inherit the disease allele and have the disease phenotype.