Activity 5: Genetic Counseling
Objective
Students will role play to explore some of the dilemmas associated with
genetic testing for late-onset disorders.
Background Information
Some diseases, such as Huntington disease and familial Alzheimer disease,
may become apparent primarily in middle age or later. Both Huntington and
familial Alzheimer are caused by dominant genes, so that only one dominant
gene is needed to produce the disorder. Therefore, an individual with an
affected parent has a fifty-fifty chance of inheriting the disorder.
Unfortunately, because both Huntington disease and familial Alzheimer
are late-onset disorders, an affected individual may already have had children
before developing any symptoms. Presymptomatic, or predictive, tests can
clarify an individual's risk for these diseases. Some of these tests involve
indirect DNA testing, which involves looking at DNA sequences physically
near -- but not part of -- the gene. This line of testing requires testing
both an affected family member and other relatives in order to diagnose
the disease in a person at risk. Other tests use direct DNA testing, which
involves a direct examination of the relevant gene in a search for mutations
in that gene. Only individuals at risk are tested by this method. However,
these diseases are currently untreatable, and individuals at risk may decide
that they would rather not know if they or other family members are destined
to suffer through the mental and physical deterioration these diseases cause.
In addition, people with these types of degenerative diseases may be denied
insurance, have difficulties obtaining employment, and are ineligible to
adopt children.
 Comparison
of the inheritance pattern of recessive and dominant disorders in a family.
Materials
For each group:
Preparation
Duplicate Genetic Testing Worksheet and distribute to students.
Instructions
- Divide the class into groups of four to six. Explain that each student
should choose one of the roles listed at the top of the case study handout.
If needed, explain the responsibilities of a genetic counselor, which include
being a sensitive, knowledgeable, and supportive listener; explaining the
nature of the genetic condition, including its background, inheritance
patterns, and possible treatments; and helping people understand the options
available to them.
- Ask the students to read carefully through the scenarios on the handout.
Have them answer the question beneath each scenario based on how they think
that person would respond.
- If time permits, have students choose another role and discuss the
consequences of the scenarios from the new viewpoint.
Discussion Questions
- What can genetic testing for a late-onset disease tell you? What can
it not tell you?
- What are the potential advantages of knowing that you carry or are
at risk for a genetic disorder? What are some of the disadvantages?
- Would you want to be tested for a late-onset disorder? Why or why not?
- If your knew that your employer would have access to the information,
would you decide to test for a late-onset disease? Why or why not? Who
do you think should have access to this information?
Extensions
- Have students contact local hospitals and public health facilities
to create a list of local genetic counseling resources. Have students interview
a genetic counselor to find out how the counselor helps people make decisions
and what ethical dilemmas the job presents. Before the interview, students
should brainstorm a list of questions to ask during the interview.
- Ask each student to write a letter as though he or she were someone
seeking advice about some aspect of genetic testing. For example, students
might pretend they are individuals who are being pressured into testing
by close relatives; individuals who are trying to decide whether or not
to test their fetus; or individuals who are trying to determine the risks
and benefits of a particular test.
After students have written their letters, ask them to exchange letters
with someone else in the class. Have them write a response to the letter
they are given. Discuss the letters and the responses with the class.
- Draw the pedigrees shown on the left on a blackboard or piece of paper.
Ask students to examine the pedigrees and note any patterns they see. Ask
them to imagine that they have been given a pedigree showing the affected
and non-affected individuals in a family. Have them discuss how they might
determine whether the trait was dominant or recessive.
Links
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Resource Book Index: Promises and Perils
