Question

Some types of muscular dystrophy are X-linked recessive disorders. A mother who is a carrier for muscular dystrophy has children with a father who doesn’t have muscular dystrophy.

A. What percentage of their sons will have the disease, and what percentage of their sons will be carriers?
B. What percentage of their daughters will have the disease, and what percentage of their daughters will be carriers?
Show your work with a Punnett Square, using XD to represent the allele not associated with muscular dystrophy and Xd to represent the allele associated with muscular dystrophy. You can copy/paste the blank table below or create a table in the submission box to complete the Punnett square.

I have seen so many answer and now I'm confused.

Answer 1

50% of the sons will have the disease while 50% will be carriers.

25% of the daughters will have the disease while 75% will be carriers.

What percentage would be carriers or have the disease?

Fifty percent of the sons will have the disease because the mother is a carrier, meaning she has one X chromosome with the mutated gene for muscular dystrophy and one X chromosome with the healthy gene. Since each son inherits one X chromosome from his mother. There is a 50% chance he will inherit the X chromosome with the mutated gene, causing the disease.

There is also a 50% chance that each son will inherit the healthy X chromosome from his mother, making him a carrier of the disease but not showing symptoms. 25% of the daughters will have the disease because the mother is a carrier and the father does not have the disease.