It’s a situation that would leave many physicians at a loss. A 55-year-old man with a family history of dementia asks his doctor about genetic testing for Alzheimer’s disease. Is there a test? Which test should be used? Is testing even appropriate? This week the Journal of the American Medical Association
published the final installment in a three-part series of user’s guides that aims to help doctors who face these kinds of situations. Given the dizzying pace at which genetic association studies are being published and the increased availability of genetic tests, both through physicians and direct-to-consumer providers, these guides could not have come at a better time.
In the introduction to the series, the authors say that although genetic association studies may one day produce numerous benefits for both science and medicine, the most likely short-term use of this type of information for clinicians is in identifying the most at-risk people in a population and providing patients with information on the likely courses their diseases will take. Although the user’s guides are intended for physicians, they are written in such a clear and concise manner that anyone interested in understanding more about genetics and how it applies to their health will find them helpful. (Unfortunately these guides are not freely available. They may be available at a local city, county or university library. They are also available for download for $15 per article.)
Summary of the three user’s guides: A. Background Concepts
The first article summarizes the key genetic concepts that clinicians must be familiar with to understand genetic association studies. There is a glossary of commonly used terms, a review of the components and structure of DNA, an explanation of human variation and a summary of the different forms that genetic association studies can take. B. Are the Results of the Study Valid?
The second article takes the reader through the major issues that need to be addressed in judging whether a genetic association study is valid, presenting a series of questions physicians should ask themselves while reading an association study. Topics addressed include determining whether the participants used in a study were chosen correctly, how to tell if the technology being used to genotype study participants worked correctly, several statistical considerations that need to be addressed (including multiple testing
) and whether the results have been replicated and are consistent with those of other studies. C. What are the Results and Will They Help Me in Caring for My Patients?
The concluding article of the series offers guidance on evaluating the magnitude and precision of a study’s findings and determining what to do with these results, based on both the study and the patient’s family history and personal characteristics.