1. A couple with two children is referred for genetic counseling because their younger son, a 12-year-old boy, has a movement disorder for which testing for juvenile Huntington disease (Case 24) is being considered. What are the ethical considerations for the family in testing?

2. A research project screened more than 40,000 consecutive, unselected births for the number of X chromosomes and the presence of a Y chromosome and correlated the sex chromosome karyotype with the sex assigned by visual inspection in the newborn nursery. The purpose of the project was to observe infants with sex chromosome abnormalities (see Chapter 6) prospectively for developmental difficulties. What are the ethical considerations in carrying out this project?

3. In the case described in the Box in the section on duty to warn, consider what might be your course of action if you were the genetic counselor and the disease in question were the following: hereditary breast and ovarian cancer due to BRCA1 mutations (see Chapter 15) (Case 7); malignant hyperthermia due to RYR1 (ryanodine receptor) mutations (see Chapter 18); early-onset, familial Alzheimer disease due to a PSEN1 (presenilin 1) mutation (see Chapter 12) (Case 4); neurofibromatosis due to NF1 mutations (see Chapter 7) (Case 34); or type 2 diabetes mellitus (Case 35).

4. Draw up a list of a dozen genes and disorders that you believe should be analyzed as secondary findings during a whole-exome or whole-genome sequence for undiagnosed diseases. Explain how and why you chose each of these dozen genes and conditions.