Question

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

Answer 1

It's 0%

Step-by-step explanation:

It's 0%

Answer 2

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