Question

question 26
two healthy individuals have a child who has huntington disease, an autosomal dominant disease. how did this happen?
a the mother had two recessive alleles.
b the mother had one recessive allele and one normal allele, and the father had two normal alleles.
c the mother had two normal alleles, and the father had one recessive and one normal allele.
d each parent had one normal and one recessive allele.
e the condition could not have been inherited from these two parents.
question 27
1 point
a phenotypically normal woman marries a man with wilson disease, a autosomal recessive disorder. they have a son who has wilson disease. if you need two copies of the recessive allele to be affected and the mother doesnt have the disease, how did the son get it?
a the woman had two recessive alleles.
b the woman must have been a carrier of one recessive allele and one normal allele.
c the woman had two dominant alleles.
d the man had two dominant alleles.
e the man had one dominant and one recessive allele.

Explanation:

Question 26

Huntington disease is an autosomal dominant disease. For a child to have an autosomal dominant disease, at least one parent should carry the dominant allele. But the parents are healthy. This indicates that it is not an inherited case from these two parents as they don't have the dominant allele (assuming normal Mendelian inheritance).

Wilson disease is an autosomal recessive disorder. The son has the disease, so he must have two recessive alleles (one from each parent). The father has Wilson disease, so he has two recessive alleles. The mother is phenotypically normal. For her to pass a recessive allele to the son (as the son needs two recessive alleles), she must be a carrier (one recessive and one normal allele).

Answer:

E. The condition could not have been inherited from these two parents.

Question 27