Draw the pedigree for this family. What could explain why Darren is unaffected but two of his children are affected?

Module 5

A. Donna and Darren have three children [2 male/1 female]. Darren’s father has hypercholesterolemia, which is transmitted in an autosomal dominant pattern. Darren gets his cholesterol levels checked frequently, and they have remained within normal limits; however, two of Donna and Darren’s three children have high plasma levels of total and LDL cholesterol. Darren doesn’t understand why his children are affected when it is clear that he is healthy [1 male affected/1 male unaffected; 1 female affected].

1. Draw the pedigree for this family.

2. What could explain why Darren is unaffected but two of his children are affected?

3. Darren returns from meeting with the genetic counsellor but still doesn’t understand what she told him. How could you help Darren understand what is going on in his family?