Answered: What can your personal genome tell you…

Science

Biology

What can your personal genome tell you about your genetic risk factors?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter16: Reproductive Technology, Genetic Testing, And Gene Therapy

Section: Chapter Questions

Problem 16QP: A couple has had a child born with neurofibromatosis. They come to your genetic counseling office...

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Should he go ahead and enroll on the chance that he would receive the DNA vaccine and that it would be more effective than chemotherapy? Bruce and his parents moved to a semi-tropical region of the United States when he was about 3 years old. He loved to be outside year-round and swim, surf, snorkel, and play baseball. Bruce was fair-skinned, and in his childhood years, was sunburned quite often. In his teen years, he began using sunscreens, and although he never tanned very much, he did not have the painful sunburns of his younger years. After graduation from the local community college, Bruce wanted an outdoor job and was hired at a dive shop. He took people out to one of the local reefs to snorkel and scuba dive. He didnt give a second thought to sun exposure because he used sunscreen. His employer did not provide health insurance, so Bruce did not go for annual checkups, and tried to stay in good health. In his late 20s, Bruce was injured trying to keep a tourist from getting caught between the dive boat and the dock. He went to an internist, who treated his injury and told Bruce he was going to give him a complete physical exam. During the exam, the internist noticed a discolored patch of skin on Bruces back. She told him that she suspected Bruce had skin cancer and referred him to a dermatologist, who biopsied the patch. At a follow-up visit, Bruce was told that he had melanoma, a deadly form of skin cancer. Further testing revealed that the melanoma had spread to his liver and his lungs. The dermatologist explained that treatment options at this stage are limited. The drugs available for chemotherapy have only temporary effects, and surgery is not effective for melanoma at this stage. The dermatologist recommended that Bruce consider entering a clinical trial that was testing a DNA vaccine for melanoma treatment. These vaccines deliver DNA encoding a gene expressed by the cancer cells to the immune system. This primes the immune system to respond by producing large quantities of antibodies that destroy melanoma cells wherever they occur in the body. A clinical trial using one such DNA vaccine was being conducted at a nearby medical center, and Bruce decided to participate. At the study clinic, Bruce learned that he would be in a Phase Ill trial, comparing the DNA vaccine against the standard treatment, which is chemotherapy, and that he would be randomly assigned to receive either the DNA vaccine or the chemotherapy. He was disappointed to learn this. He thought he would be receiving the DNA vaccine.
James sees an online ad for an at-home genetic test that promises to deliver personalized nutritional advice based on an individuals genetic profile. The company can test for genetic variations, the advertisement states, that predispose individuals to developing health conditions such as heart disease and bone loss or that affect how they metabolize certain foods. If such variations are detected, the company can provide specific nutritional advice that will help counteract their effects. Always keen to take any steps available to ensure the best possible health for their family, James and his wife (Sally) decide that they both should be tested, as should their 11-year-old daughter (Patty). They order three kits. Once the kits arrive, the family members use cotton swabs to take cell samples from their cheeks and place the swabs in individually labeled envelopes. They mail the envelopes back to the company, along with completed questionnaires regarding their diets. Four weeks later, they receive three individual reports detailing the test results and providing extensive guidelines about what foods they should eat. Among the results is the finding that James has a particular allele in a gene that may make him vulnerable to the presence of free radicals in his cells. The report suggests that he increase his intake of antioxidants, such as vitamins C and E, and highlights a number of foods that are rich in those vitamins. The tests also show that Sally has several genetic variations that indicate that she may be at risk for elevated bone loss. The report recommends that she try to minimize this possibility by increasing her intake of calcium and vitamin D and lists a number of foods she could emphasize in her diet. Finally, the report shows that Patty has a genetic variation that may mean that she has a lowered ability to metabolize saturated fats, putting her at risk for developing heart disease. The report points to ways in which she can lower her intake of saturated fats and lists various types of foods that would be beneficial for her. A number of companies now offer genetic-testing services, promising to deliver personalized nutritional or other advice based on peoples genetic profiles. Generally, these tests fall into two different categories, with individual companies offering unique combinations of the two. The first type of test detects alleles of known genes that encode proteins that play an established role in, for example, counteracting free radicals in cells or in building up bone. In such cases, it is easy to see why individuals carrying alleles that may encode proteins with lower levels of activity may be more vulnerable to free radicals or more susceptible to bone loss. A second type of test examines genetic variations that may have no clear biological significance (i.e., they may not occur within a gene or may not have a detectable effect on gene activity) but have been shown to have a statistically significant correlation with a disease or a particular physiological condition. For example, a variation may frequently be detected in individuals with heart disease even though the reason for the correlation between the variation and the disease may be entirely mysterious. Do James and Sally have any guarantees that the tests and recommendations are scientifically valid?
James sees an online ad for an at-home genetic test that promises to deliver personalized nutritional advice based on an individuals genetic profile. The company can test for genetic variations, the advertisement states, that predispose individuals to developing health conditions such as heart disease and bone loss or that affect how they metabolize certain foods. If such variations are detected, the company can provide specific nutritional advice that will help counteract their effects. Always keen to take any steps available to ensure the best possible health for their family, James and his wife (Sally) decide that they both should be tested, as should their 11-year-old daughter (Patty). They order three kits. Once the kits arrive, the family members use cotton swabs to take cell samples from their cheeks and place the swabs in individually labeled envelopes. They mail the envelopes back to the company, along with completed questionnaires regarding their diets. Four weeks later, they receive three individual reports detailing the test results and providing extensive guidelines about what foods they should eat. Among the results is the finding that James has a particular allele in a gene that may make him vulnerable to the presence of free radicals in his cells. The report suggests that he increase his intake of antioxidants, such as vitamins C and E, and highlights a number of foods that are rich in those vitamins. The tests also show that Sally has several genetic variations that indicate that she may be at risk for elevated bone loss. The report recommends that she try to minimize this possibility by increasing her intake of calcium and vitamin D and lists a number of foods she could emphasize in her diet. Finally, the report shows that Patty has a genetic variation that may mean that she has a lowered ability to metabolize saturated fats, putting her at risk for developing heart disease. The report points to ways in which she can lower her intake of saturated fats and lists various types of foods that would be beneficial for her. A number of companies now offer genetic-testing services, promising to deliver personalized nutritional or other advice based on peoples genetic profiles. Generally, these tests fall into two different categories, with individual companies offering unique combinations of the two. The first type of test detects alleles of known genes that encode proteins that play an established role in, for example, counteracting free radicals in cells or in building up bone. In such cases, it is easy to see why individuals carrying alleles that may encode proteins with lower levels of activity may be more vulnerable to free radicals or more susceptible to bone loss. A second type of test examines genetic variations that may have no clear biological significance (i.e., they may not occur within a gene or may not have a detectable effect on gene activity) but have been shown to have a statistically significant correlation with a disease or a particular physiological condition. For example, a variation may frequently be detected in individuals with heart disease even though the reason for the correlation between the variation and the disease may be entirely mysterious. Do you think that companies should be allowed to market such tests directly to the public, or do you believe that only a physician should be able to order them?
James sees an online ad for an at-home genetic test that promises to deliver personalized nutritional advice based on an individuals genetic profile. The company can test for genetic variations, the advertisement states, that predispose individuals to developing health conditions such as heart disease and bone loss or that affect how they metabolize certain foods. If such variations are detected, the company can provide specific nutritional advice that will help counteract their effects. Always keen to take any steps available to ensure the best possible health for their family, James and his wife (Sally) decide that they both should be tested, as should their 11-year-old daughter (Patty). They order three kits. Once the kits arrive, the family members use cotton swabs to take cell samples from their cheeks and place the swabs in individually labeled envelopes. They mail the envelopes back to the company, along with completed questionnaires regarding their diets. Four weeks later, they receive three individual reports detailing the test results and providing extensive guidelines about what foods they should eat. Among the results is the finding that James has a particular allele in a gene that may make him vulnerable to the presence of free radicals in his cells. The report suggests that he increase his intake of antioxidants, such as vitamins C and E, and highlights a number of foods that are rich in those vitamins. The tests also show that Sally has several genetic variations that indicate that she may be at risk for elevated bone loss. The report recommends that she try to minimize this possibility by increasing her intake of calcium and vitamin D and lists a number of foods she could emphasize in her diet. Finally, the report shows that Patty has a genetic variation that may mean that she has a lowered ability to metabolize saturated fats, putting her at risk for developing heart disease. The report points to ways in which she can lower her intake of saturated fats and lists various types of foods that would be beneficial for her. A number of companies now offer genetic-testing services, promising to deliver personalized nutritional or other advice based on peoples genetic profiles. Generally, these tests fall into two different categories, with individual companies offering unique combinations of the two. The first type of test detects alleles of known genes that encode proteins that play an established role in, for example, counteracting free radicals in cells or in building up bone. In such cases, it is easy to see why individuals carrying alleles that may encode proteins with lower levels of activity may be more vulnerable to free radicals or more susceptible to bone loss. A second type of test examines genetic variations that may have no clear biological significance (i.e., they may not occur within a gene or may not have a detectable effect on gene activity) but have been shown to have a statistically significant correlation with a disease or a particular physiological condition. For example, a variation may frequently be detected in individuals with heart disease even though the reason for the correlation between the variation and the disease may be entirely mysterious. What kinds of regulations, if any, should be in place to ensure that the results of these tests are not abused?
James sees an online ad for an at-home genetic test that promises to deliver personalized nutritional advice based on an individuals genetic profile. The company can test for genetic variations, the advertisement states, that predispose individuals to developing health conditions such as heart disease and bone loss or that affect how they metabolize certain foods. If such variations are detected, the company can provide specific nutritional advice that will help counteract their effects. Always keen to take any steps available to ensure the best possible health for their family, James and his wife (Sally) decide that they both should be tested, as should their 11-year-old daughter (Patty). They order three kits. Once the kits arrive, the family members use cotton swabs to take cell samples from their cheeks and place the swabs in individually labeled envelopes. They mail the envelopes back to the company, along with completed questionnaires regarding their diets. Four weeks later, they receive three individual reports detailing the test results and providing extensive guidelines about what foods they should eat. Among the results is the finding that James has a particular allele in a gene that may make him vulnerable to the presence of free radicals in his cells. The report suggests that he increase his intake of antioxidants, such as vitamins C and E, and highlights a number of foods that are rich in those vitamins. The tests also show that Sally has several genetic variations that indicate that she may be at risk for elevated bone loss. The report recommends that she try to minimize this possibility by increasing her intake of calcium and vitamin D and lists a number of foods she could emphasize in her diet. Finally, the report shows that Patty has a genetic variation that may mean that she has a lowered ability to metabolize saturated fats, putting her at risk for developing heart disease. The report points to ways in which she can lower her intake of saturated fats and lists various types of foods that would be beneficial for her. A number of companies now offer genetic-testing services, promising to deliver personalized nutritional or other advice based on peoples genetic profiles. Generally, these tests fall into two different categories, with individual companies offering unique combinations of the two. The first type of test detects alleles of known genes that encode proteins that play an established role in, for example, counteracting free radicals in cells or in building up bone. In such cases, it is easy to see why individuals carrying alleles that may encode proteins with lower levels of activity may be more vulnerable to free radicals or more susceptible to bone loss. A second type of test examines genetic variations that may have no clear biological significance (i.e., they may not occur within a gene or may not have a detectable effect on gene activity) but have been shown to have a statistically significant correlation with a disease or a particular physiological condition. For example, a variation may frequently be detected in individuals with heart disease even though the reason for the correlation between the variation and the disease may be entirely mysterious. Do you think parents should be able to order such a test for their children? What if the test indicates that a child is at risk for a disease for which there is no known cure?
If your father were diagnosed with an inherited disease that develops around the age of 50, would you want to be tested to find out whether you would develop this disease? If so, when would you want to be tested? As a teenager or sometime in your 40s? If not, would you have children?
Mary and Marcie. identical twins, go to the same internist who is also a faculty member at a major medical center. At their last visit, they each received a brochure describing a genetics research program recently launched by the hospital and its affiliated university. Researchers were asking for volunteers to fill out a questionnaire and a consent form, donate a blood sample, and have their medical records encoded and transferred to a database. The goal was to enroll 100,000 participants, and the brochure noted that over 10,000 people had already agreed to participate. The blood sample would be used to extract DNA. which would be encoded with the same number as the medical records. This DNA would be used to search for genes associated with conditions such as arthritis, diabetes, and Alzheimer disease. The idea is that researchers interested in studying arthritis would use the medical records to identify which participants have the condition and then use DNA from those individuals to find genetic similarities that are not present in participants who do not have arthritis. The genetic similarities help identify regions of the genome that contain genes associated with arthritis. These regions can then be studied in detail to identify and isolate genes that may be associated with arthritis and other inflammatory disorders. In exchange for enrolling, participants would be informed about any genetic conditions or predispositions to genetic disease they carry and would receive free access to testing. After discussing the brochure. Mary decided to enroll, but Marcie decided she did not want to do so. She said she did not want to know what diseases she may develop or which disease genes she may carry. At their next annual visit. Marys internist told her that because her questionnaire indicated that some relatives had Alzheimer disease, her DNA was used in a study to identify risk genes. He said she had been identified as a carrier of a gene that greatly increased the likelihood that she would develop Alzheimer disease. The physician told her that age was the greatest risk factor, and while it was not 100% certain she would become a victim of Alzheimer disease, the gene she carries is a factor in 2025% of all cases. Mary asked if there was anything she could do about these findings. The internist told her that exercise, controlling blood pressure and cholesterol levels, as well as participating in mentally challenging activities such as reading or playing a musical instrument may all help reduce her chances of developing this disease. Mary then asked if Marcie was going to be told about Marys genetic risk, and the internist said that he would not tell her. For the next few days. Mary was conflicted about the situation. Marcie was an Identical twin, and If Mary carried a gene predisposing her to Alzheimer disease. Marcie must carry the same gene. Marcie did not exercise with Mary, had high blood pressure, and little interest in reading or social activities. Mary did not know whether she should tell Marcie. If you were advising Mary, what would you say? Should she tell Marcie about the risk? Should she not tell her, but instead try to get Marcie to exercise and be more social? Should Mary ask their internist to talk with Marcie about this?
You may have heard about the diet that is based on a persons blood type and claims to restore the bodys natural genetic rhythms and improve health. Research may one day reveal exactly which foods might best turn on and off specific genes to defend against specific chronic diseases. No doubt marketers will rush to fill grocery shelves with foods manufactured to match genetic profiles. Why do you think these genetic approaches to diet and health might be more or less appealing than eating patterns that include a variety of fruits, vegetables, whole grains, milk products, and meats?
The following family has a history of inherited breast cancer. Betty (grandmother) does not carry the gene. Don, her husband, does. Dons mother and sister had breast cancer. One of Betty and Dons daughters (Sarah) has breast cancer; the other (Karen) does not. Sarahs daughters are in their 30s. Dawn, 33, has breast cancer; Debbie, 31, does not. Debbie is wondering if she will get the disease because she looks like her mother. Dawn is wondering if her 2-year-old daughter (Nicole) will get the disease. a. Draw a pedigree indicating affected individuals and identify all individuals. b. What is the most likely mode of inheritance of this trait? c. What are Dons genotype and phenotype? d. What is the genotype of the unaffected women (Betty and Karen)? e. A genetic marker has been found that maps very close to the gene. Given the following marker data for chromosomes 4 and 17, which chromosome does this gene map to? f. Using the same genetic marker, Debbie and Nicole were tested. The results are shown in the following figure. Based on their genotypes, is either of them at increased risk for breast cancer?
If a test were available that could tell you whether you were likely to develop a disorder such as schizophrenia later in life, would you take the test? Why or why not? Rachel asked to see a genetic counselor because she was concerned about developing schizophrenia. Her mother and maternal grandmother both had schizophrenia and were institutionalized for most of their adult lives. Rachels three maternal aunts are all in their 60s and have not shown any signs of this disease. Rachels father is alive and healthy, and his family history does not suggest any behavioral or genetic conditions. The genetic counselor discussed the multifactorial nature of schizophrenia and explained that many candidate genes have been identified that may be mutated in individuals with the condition. However, a genetic test is not available for presymptomatic testing. The counselor explained that based on Rachels family history and her relatedness to individuals who have schizophrenia, her risk of developing it is approximately 13%. If an altered gene is in the family and her mother carries the gene, Rachel has a 50% chance of inheriting it.
Identify a possible advantage and a possible disadvantage of a genetic test that would identify genes in individuals that increase their probability of having Alzheimer’s disease later in life.
Zoe has cystic fibrosis. Which of the following is the most likely explanation? Zoe probably inherited one faulty allele from her father, who is a earner, and one normal allele from her mother. Zoe probably inherited one faulty allele from her mother, who must also have cystic fibrosis, and one normal allele from her father. Zoe must have inherited faulty alleles from both parents, both of whom must also have cystic fibrosis, Zoe must have inherited faulty alleles from both parents, both of whom are earners.