Question

homework - complete dominance inheritance pattern
von willebrand disease is an autosomal dominant disorder in which blood does not clot properly. if a person with normal blood clotting (dd) and a person who is homozygous for the disease (dd) have children, what are the possible phenotypes for their children?
○ there is a 25% chance they will have normal blood clotting and a 75% chance they will have von willebrand disease.
○ there is a 50% chance they will have normal blood clotting and a 50% chance they will have von willebrand disease.
○ there is a 100% chance they will have von willebrand disease.
○ there is a 100% chance they will have normal blood clotting

Explanation:

Step1: Determine gametes

The person with normal blood clotting (dd) can only produce gametes with the allele \(d\). The person homozygous for the disease (DD) can only produce gametes with the allele \(D\).

Step2: Use Punnett square

When we cross \(dd\times DD\), all of the offspring will have the genotype \(Dd\). In autosomal - dominant inheritance, an individual with at least one dominant allele (in this case, \(D\)) will express the dominant trait (Von Willebrand disease).

Answer:

There is a 100% chance they will have Von Willebrand disease.