Scanning a person's genes for mutations linked to a particular disease already has saved some lives and dramatically improved others. Some gene tests can alert patients and physicians to an inherited tendency toward a disorder and lead to increased surveillance or other preventive treatments. For example in familial adenomatous polyposis (FAP), a rare form of inherited colon cancer, lives have been saved through testing for the mutated gene linked to FAP and aggressive monitoring for early removal of colon growths or even the entire colon.

Interpreting the meaning of a negative test for the FAP mutation, however, is not straightforward. The possibility of developing the disorder is not ruled out because different mutations may be responsible for the disease in different individuals. However, some physicians who order tests and interpret them for patients are unaware of these subtleties. An article published in the New England Journal of Medicine reported that one-third of physicians in a study group misinterpreted negative results in the FAP mutation test. If the researchers monitoring the study had not intervened, those doctors would have advised their patients to discontinue aggressive surveillance (colonoscopies), advice that could have had disastrous consequences. Comprehensive education of medical professionals is considered critical to the effective introduction of the new genetics into clinical practice.