Chapter 15, Problem 2CS

James sees an online ad for an at-home genetic test that promises to deliver personalized nutritional advice based on an individual’s 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 people’s 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?