Question

Vitamin D - resistant rickets is an X-linked dominant bone disorder. A man with this form of rickets marries a normal woman. What proportion of the couple's daughters is expected to have vitamin D - resistant rickets?a. 50%b. 100%c. 25%d. 0%

Answer 1

Answer:

b. 100%

Explanation:

Since, Vitamin D - resistant rickets is an X-linked dominant bone disorder, it is possible that the dominant bone disorder mask the expression of the other traits.

Given that,  A man with this form of rickets ; lets say X°X° marries a normal woman; (XX). The cross can be shown as:

         X°          X°

X       X°X       X°X

X       X°X       X°X

From the punnet square, it shows that all the offspring have an allele in each of their copy carrying a vitamin D - resistant rickets disorder.