A nurse has completed a family pedigree on a patient with a known autosomal dominant inheritance disorder. No one else in the family has been affected by this disorder. How does the nurse explain this finding to the patient?

Question

A.
Genetic variation occurred via a mutation.
B.
Information about the family is incorrect.
C.
The patient is not biologically related to the family.
D.
The patient's diagnosis must be incorrect.

Answer 1

ANS: A
Most autosomal dominant inheritance disorders are seen in families in which multiple members in different generations have been affected by the disorder. However, the variant allele may arise from a mutation, in which case the affected person will be the first known person in the family to be affected. The other options are incorrect.