A couple comes into the family counseling center and wants information on genetic counseling. They are thinking of starting a family but the wife has a family history of Tay Sachs disease. Kieran is a genetic counselor who will explain the services available at the center. Kieran’s discussion will include genetic mutation, tests that may be done during pregnancy, and advances being made in genetic therapy. What information can Kieran give the couple regarding the services of the genetic counseling center?

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?

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.

As a physician, you deliver a baby with protruding heels and clenched fists with the second and fifth fingers over-lapping the third and fourth fingers. a. What genetic disorder do you suspect the baby has? b. How do you confirm your suspicion?

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?

You are in charge of a new gene therapy clinic. Two cases have been referred to you for review and possible therapy. Case 1. A mutation in the promoter of a proto-oncogene causes the gene to make too much of its normal product, a receptor protein that promotes cell division. The uncontrolled cell division has caused cancer. Case 2. A mutation in an exon of a tumor-suppressor gene makes this gene nonfunctional. The product of this gene normally suppresses cell division. The mutant gene cannot suppress cell division, and this has led to cancer. What treatment options can you suggest for each case?

Genetics in Practice case studies are critical-thinking exercises that allow you to apply your new knowledge of human genetics to real-life problems. Case study Michelle was a 42-year-old woman who had declined counselling and amniocentesis at 16 weeks of pregnancy but was referred for genetic counseling after an abnormal ultrasound at 20 weeks of gestation. After the ultrasound, a number of findings suggested a possible chromosome abnormality in the fetus. The ultrasound showed swelling under the skin at the back of the fetuss neck; shortness of the femur, humerus, and ear length; and underdevelopment of the middle section of the fifth finger. Michelles physician performed an amniocentesis and referred her to the genetics program. Michelle and her husband did not want genetic counseling before receiving the results of the cytogenetic analysis. This was Michelles third pregnancy; she and her husband, Mike, had a 6-year-old daughter and a 3-year-old son. At their next session, the counselor informed the couple that the results revealed trisomy 21, explored their understanding of Down syndrome, and elicited their experiences with people with disabilities. She also reviewed the clinical concerns revealed by the ultrasound and associated anomalies (mild to severe intellectual disability, cardiac defects, and kidney problems). The options available to the couple were outlined. They were provided with a booklet written for parents making choices after the prenatal diagnosis of Down syndrome. After a week of careful deliberation with their family, friends, and clergy, they elected to terminate the pregnancy. Should physicians discourage a 42-year-old woman from having children because of an increased chance of a chromosomal abnormality?