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

Answer:

It's 0%

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