Human Genetic Variation
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Activity 3 - Molecular Medicine Comes of Age

Question 1 What is the biological problem facing Firm A with respect to Drug X?

There is an inconsistent response to Drug X among asthma patients, that is, the drug does not work the same way on all patients.

Question 2 Describe asthma in your own words (refer to the Team Coordinator and Physiologist handouts).

Asthma is a fairly common condition that involves breathing difficulties. The bronchioles contract abnormally. It often is associated with an allergic reaction to foreign substances.

Question 3 What is Drug X designed to do for asthma sufferers (refer to the Team Coordinator and Physiologist handouts)?

The drug opens up the bronchioles so that the asthma patient can breathe more easily.

Question 4 Look at the preliminary test results (refer to the Biostatistician handout). Can you predict which group will be helped most or least by Drug X? For example, does the sex of the individual make a difference? Does having pets make a difference? Explain your answers.

No. There is no way to make a prediction, because there is no pattern in the response to the drug. Neither the sex of the individual nor the presence of pet dander makes a difference in the response.

Question 5 What does the example of ApoE (refer to the Molecular Biologist handout) suggest might be happening with Drug X? Based on this example, what might Firm A investigate?

The data indicate that response to the Alzheimer drug might be based on variations in the ApoE gene. Perhaps Firm A should explore genetic differences with respect to response to Drug X.

Question 6 Firm A's vice president for research (your teacher) will provide you with some new data. What do the new data reveal about Drug X?

There is a difference in response to the drug on the basis of the genetic variations in the patient population.

Question 7 What would be an appropriate way to prescribe Drug X?

It would be appropriate to test each asthma patient for his or her genotype to determine whether Drug X will be effective with that individual.

Question 8 Has your team solved the biological problem facing the company with respect to Drug X? What new problems has it raised?

The team's work has answered the basic biological question about response to Drug X. It has raised new questions about the ability to test all asthma sufferers. For example, how expensive is it to do that? Will physicians order the test? Will it be covered by health insurance? Who will have access to the information that results from the genetic test? How will Firm A educate physicians and other health care professionals so they understand the test and the results and so they can explain this information to their patients?

9. Repeat the same process with the teams from Firm B, but use a transparency made from Master 3.12 to guide the discussion.

Again, to keep all students involved in the discussion, invite students from the other firm to contribute to the discussion by asking questions and even offering suggestions, as appropriate.

Question 1 What is the problem facing Firm B with respect to Drug Y (refer to the Team Coordinator handout)?

Drug Y is a successful treatment for cystic fibrosis (CF) and is the firm's leading product. Firm B needs to keep looking ahead, however, and begin thinking about new treatments for CF that take advantage of what scientists have learned about the condition and, in the future, might be able to supplement or even replace income that the company is now receiving from Drug Y.

Question 2 Describe cystic fibrosis in your own words (refer to the Physiologist handout).

CF is a genetic disease that causes the body to produce an abnormally thick, sticky mucus. This mucus clogs the airways and other ducts and passages in the body and provides an ideal breeding ground for many microorganisms. CF patients have frequent airway infections and often show poor weight gain and slowed growth and development.

Question 3 What have we learned in the past few years about the cause of CF (refer to the Molecular Biologist handout)?

The most common CF mutation leads to one missing amino acid in the CFTR protein. The loss of this single amino acid causes the protein to be misshapen in such a way that most of it is destroyed instead of being inserted into the cell membrane. The absence of properly functioning CFTR protein in the cell membrane leads to abnormal movement of chloride ions and water in and out of the cell and production of thick, sticky mucus.

Question 4 What is Drug Y (and most other current treatments) designed to do for CF patients (refer to the Physician handout and discuss what goes in the last column of the table provided)?

Most existing treatments for CF focus on alleviating the symptoms of the disease, for example, removing airway mucus, reducing infection, and improving nutrition. Students should discover this by completing the last column in the table provided on the Physician handout.

Question 5 Firm B's vice president for research (your teacher) will provide you with some new information. What clue does this new information provide about how Firm B might approach developing new treatments for CF?

The important clue that students should gain from this new information is that understanding the biological basis of CF has allowed these researchers to propose a way to correct the problem in CF cells. This is a different approach to treatment from treating its consequences.

Question 6 What new approaches do you recommend Firm B consider as it attempts to design and develop one or more new treatments for CF?

Students will not be able to suggest detailed approaches to developing treatments, but they should be able to propose general approaches that address each of the items on the flow chart on the Molecular Biologist handout. For example, students might suggest developing treatments that would correct or replace the defective CF genes; replace the missing amino acid in the CFTR protein; cause the CFTR protein to fold properly despite the missing amino acid; prevent the defective CFTR protein from being destroyed before it reaches the cell membrane; introduce functional CFTR protein into the cell from another source; or create another mechanism in the cell that would regulate the movement of chloride ions.

Question 7 Has your team solved the problem facing the company with respect to Drug Y? What new problems has it raised?

No, the team has not "solved the problem" facing the company, but it has suggested several directions that the company may want to investigate as it develops new CF treatments. New problems that the team's work has raised include problems common to all development of new drugs: deciding on an approach to try, allocating funds to pay for development and clinical testing, and going through the process of gaining FDA approval for the new treatment.

assessmentYou may wish to ask the students who worked on Firm A’s problem to answer the questions related to Firm B’s problem, and vice versa.

10. Challenge the students to generalize what they have learned by answering the following questions:

. How is genetic variation related to the use of drugs?

Students should understand that genetic differences between people may cause them to respond differently to therapeutic drugs. As scientists begin to detect such genetic differences, physicians will become more sensitive to individual variation in response to drugs and may even begin to prescribe drugs based on differences in genotype.

. How will pharmaceutical companies likely use our increasing understanding of human genetic variation?

Pharmaceutical companies may begin to design drugs that are intended for people who have certain genotypes. They also may resurrect products that were not viable in the past because of their unpredictable, negative side effects on certain people.

. How can discovering the genes associated with genetic disorders help scientists develop new approaches to treatment?

puzzle pieceRefocusing students’ attention on the opening statement draws them back to the activity’s major concept.

As Figure 6 shows, mapping and cloning the genes associated with genetic disorders helps scientists discover their underlying biochemical mechanisms, and this can suggest new approaches to treatment.

Another way to raise these issues with students is to display a transparency made from Figure 6 and ask students to explain how the activity they just completed relates to the beginning and end points of the arrows on the diagram.

11. Display again the transparency you made from Molecular Medicine Comes of Age. Ask students to explain what it means and provide examples that illustrate or provide evidence for this point.

12. Close the activity by asking students what they think the transparency's title means.

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