This is an edited version of a classroom lesson initially developed by:
Sheila Matus, Oyster Bay High School, Oyster Bay, Long Island, NY
Courses for Which the Lesson is Intended:
This lesson is intended for use in any biology course - introductory
or advanced - that includes a unit on genetics or reproduction.
Types of Teaching/Learning Activities Employed in this Lesson:
Students read a story about a girl who grows up in a family affected
by the heritable, disabling and fatal medical condition called Huntington's
Disease. They then meet in cooperative learning groups to define the meaning
of several relevant terms and to answer questions about ethical issues
related to the available genetic test for Huntington's Disease. A classroom
discussion is then held to explore the differences among the group's responses
to the questions
Category that Best Describes this Lesson:
Ethics/Values Issues Raised by this Lesson:
General ethical issues related to modern biotechnology; specific ethical
issues related to testing for genetic diseases; the ethical consequences
of the disclosure of genetic information.
1. In preparation for the lesson the students are given a homework assignment requiring the written definition and explanation of a series of terms related to the lesson.
2. At the beginning of the class, students are given ten minutes to read the brief introductory story, "My Friend Linda."
3. The class is divided into cooperative learning groups of three or four students each.
4. Working among themselves each group:
a) discusses and attempts to formulate a set of definitions and descriptions for the terms in the homework assignment.5. The teacher asks for volunteers among the reporters for the learning groups to present definitions of the assigned terms. With the help of other students the definitions are discussed and, if necessary modified, with the goal of producing a set of definitions that the teacher and class find acceptable.
b) discusses and attempts to reach a consensus in response to the discussion questions
6. The teacher then leads a class discussion based on the questions,
which is designed to expose the students to the many unavoidable ethical
issues that our society faces as a result of the development of biotechnology
and its application to genetic testing.
Student Homework Assignment:
Define and explain each of the following terms:
2. autosomal dominant inheritance
4. ethical issue
5. genetic testing
When I was ten years old, my best friend Linda's father died. We knew he had been very sick, but Linda told us nothing else about his illness. When you are ten, the death of someone close to you is usually too frightening to talk about. Linda's friends would never have dreamed of asking, "What did your daddy die of?"
Although she moved to another city when we were both 13, I kept in touch with Linda. When she was twenty she told me that her brother Peter was ill. Peter was 31, married, and had a two-year-old daughter. Over the next three years I learned from Linda that his condition had gotten much worse and he had been confined to a hospital. A year later Linda wrote to tell me that he had died and that her unmarried sister Hope, then 33, was showing early signs of the same disease that had taken the lives of her father and brother.
Linda disclosed in that letter that her father, Peter, and now Hope were victims of Huntington's Disease. She explained that it is a genetic disease caused by an autosomal dominant gene. Anyone who inherits the gene will suffer physical and mental deterioration, usually beginning about age forty. Symptoms from the most lethal form of the gene can sometimes begin several years earlier. The disease begins by causing a variety of physical symptoms. The victim loses muscular control, soon becoming unable to walk normally or do tasks requiring any coordinated motion. Speech becomes difficult and then impossible. Within a few years serious mental disturbance occurs followed inevitably by death. There is no cure, nor effective treatment for the disease.
One purpose of Linda's letter was to seek my advice. She faces a very
difficult decision. Genetic research has identified the form of the gene
that causes Huntington's disease. A test has been developed in which the
gene is cloned and DNA analysis can be done to determine if a person is
carrying the lethal allele. Linda is now 24 and she has fallen in love.
She knows there is a 50% chance that she inherited the lethal gene from
her father. The question she has asked me to help her with is should she
have the test done to find out whether or not she is doomed to suffer the
same fate as her father, brother and sister?
1. Why might Linda not wish to be tested for the Huntington's Disease gene?
2. Do you think that Linda should be tested? Why?
3. If Linda is tested and plans to be married, should she tell her boyfriend about the results?
4. If she decides not to be tested, should she explain to her boyfriend that she has a 50% chance of having the lethal gene, and that if she has it, any children she has will also have a 50% chance of inheriting it from her?
5. Should Linda's test results be available to health insurance companies; to a potential employer; to the government? Should anyone else be informed of the test results without Linda's permission?
6. Suppose Linda had an identical twin sister. Should that sister have the right to know Linda's test results? Suppose that sister does not want to be tested, and since it would be difficult for Linda to hide either negative or positive test results from her, should the sister have the right to prevent Linda from being tested?
7. Should being tested for the gene be a requirement for anyone with a family history of Huntington's Disease?
8. Suppose a cure, or effective treatment for Huntington's Disease was discovered. Would this affect your answers to any of the other questions?
9. As you have seen in responding to these questions, genetic testing
involves decisions of an ethical nature that have complicated possible
effects on the person being tested, family members and society. Since most
people will not be aware of all these issues, should genetic counseling
be required before an individual undergoes genetic testing? If so, who
should pay for it?
There is no doubt that biotechnology and the Human Genome Project will continue to result in new technologies that will become available to medical practitioners and to the public. It is important that in addition to learning about the tremendous potential benefits of this biotechnological revolution, students become aware of the complex social and ethical issues that will accompany this development.
In this lesson students learn that it is now possible for an individual with a family history of Huntington's Disease, a lethal inherited disease resulting from a genetic defect, to have a test to find out if he or she has inherited the defect. Since the disease is incurable and always fatal, the obvious question is whether or not an individual is better off knowing if the defect has indeed been inherited. Knowledge would be helpful in many ways. If the results are negative it means the individual can live a normal life without fearing an early, horrible death. If the results are positive it can help an individual prepare for the inevitable. An individual with the inherited gene may decide not to have children, each of whom would have a 50-50 chance of inheriting the lethal defect. On the other hand an individual may prefer to live with the uncertainty of not knowing rather than risk having to live with the certainty that she or he is doomed. Question 6 points out that the decision to have the test results in information that can affect relatives as well as the individual in question. Parents and children of an individual being tested, as well as the more unusual case of an identical twin, could learn that they are either definite or possible carriers of the defect from the results obtained by a person who chooses to be tested. This can clearly present thorny ethical problems for someone who is considering being tested.
It is important to emphasize that serious ethical issues are by no means confined to the case of genetic testing for a fatal incurable disease. Genetic testing of any sort is associated with serious potential consequences that most people are not aware of. In many cases an individual is advised to see a genetic counselor before making a decision about whether to be tested. It has been suggested by some of the people who have studied this issue that such counseling should be made mandatory. Before any action could be taken on such a suggestion it would be necessary to define what constitutes adequate counseling. At present, genetic testing and counseling are expensive and are not financially feasible for the majority of people. This raises a general ethical concern about how a democratic society can assure fair access to present and future expensive biomedical technological procedures.
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