A nurse has completed a family pedigree on a patient with a known ...

[burchfield96]

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?
 
  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.

Question 2

A nurse is counseling a couple whose child has been diagnosed with cystic fibrosis. They understand that this is an inherited disease, but don't know how the child got it, as neither of them is affected. What response by the nurse is best?
 
  A.
  Are you certain that you (points to man) are the biological father?
  B.
  Maybe each of you has a mild case that hasn't been diagnosed yet.
  C.
  Something in your environment must have altered one of the genes.
  D.
  This is a recessive disorder, meaning that each of you is just a carrier.

[jasonq]

Answer to Question 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.

Answer to Question 2

ANS: D
Cystic fibrosis is an example of an autosomal recessive inheritance problem. Both parents carry an altered gene for this condition (carriers), but both parents must pass this altered version on to their child in order for it to be expressed. Asking if the man is the father is accusatory and unhelpful. Each parent has the gene, but not the disease, so they don't have a mild form. An environmental factor can cause genetic mutations, but this is not the case in this type of inheritance.