Hemophilia is an X-linked recessive disorder (Xh) that is passed through generations and can be traced by using a pedigree. What is the probability that a female child of Charles and Marie would suffer from hemophilia?

a. 0 percent

b. 25 percent

c. 50 percent

d. 100 percent

Since hemophilia is an X-linked recessive disorder, the probability depends on the X alleles.

So, if father has dominant allele (H), the probability that a female child would suffer from hemophilia (genotype: hh) is 0%, no matter of mother's genotype:

Father Mother

Parents: H x Hh

Daughter: HH or Hh

Father Mother

Parents: H x HH

Daughter: HH

Father Mother

Parents: H x hh

Daughter: Hh or Hh

But, if the father has recessive allele, the probability that a female child would suffer from hemophilia (genotype: hh) will depend on mother's genotype.

If mother is dominant homozygous, there will be 0% of possibility:

Father Mother

Parents: h x HH

Daughter: Hh

If mother is recessive homozygous, the possibility is 100%:

Father Mother

Parents: h x hh

Daughter: hh

If mother is heterozygous, the possibility is 50%:

Father Mother

Parents: h x Hh

Daughter: Hh or hh