Question

Some humans exhibit piebald spotting: patches of skin that lack pigmentation. The condition results from the inability of pigment-producing cells to migrate properly during development. Two adults with piebald spotting have one child who has this characteristic and a second child with normal skin pigmentation.

Required:
a. Is the piebald spotting trait dominant or recessive? What information led you to this answer?
b. What are the genotypes of the parents?

Answer 1

A. The piebald spotting trait is dominant. If 3/4 people present with it, it’s likely the dominant trait.

B. Since the parents had a child who does not present with piebald spotting, the genotypes are heterozygous. (Pp)