Assume that the trait in question is autosomal dominant. What is the likelihood that two heterozygotes will ha

Question

Assume that the trait in question is autosomal dominant. What is the likelihood that two heterozygotes will have an offspring with the dominant phenotype?

a. 0%

b. 25%

c. 50%

d. 75%

e. 100%

Answer 1

For autosomal dominant genes, a single abnormal gene on one of the autosomal chromosomes (one of the first 22 "non-s*x" chromosomes) from either parent can cause the disease.

If each parent is heterozygote (Aa), then they would both should the autosomal dominant trait.  The AA homozyote would also show the trait.  Only the aa double recessive would not.

The answer is 25%.