Question

Please HELP////2. A couple are both phenotypically normal, but their son suffers from hemophilia, a sex-linked recessive disorder. What fraction of their children are likely to suffer from hemophilia? What fraction are likely to be carriers (Heterozygous)?

Answer 1

Answer:

1/4 suffer from hemophilia

1/4 are heterozygous

Explanation:

So since they are normal but their son isn't it is assumed that the mom is the carrier since the dad has to be X^HY

X^HY x  X^HX^h

Set up a pedigree

X^HX^H X^HX^h

X^HY     X^hY

1/4 suffer from hemophilia (X^h)

1/4 are heterozygous (X^HX^h)