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Transcript: Medscape video from Muin J. Khoury M.D., Ph.D.
Director, Office of Public Health Genomics


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Hello everyone, I am Dr. Muin Khoury, director of the Office of Public Health Genomics at the Centers for Disease Control and Prevention. I am speaking to you as part of the CDC Expert Series on Medscape.

Today I would like to talk to you about personal genomic tests that consumers can buy on the Internet to measure their genetic risk for multiple diseases. You may have heard about different tests. You may even have had patients ask you about these tests or share the results with you.

In a recent survey of 1880 healthcare providers,[1] we found that 42% of providers were aware of personal genomic tests. Moreover, 42% of the aware providers had one or more patients in the past year ask him or her about having a personal genomic test, and 15% had brought their test results to the [provider] for discussion.

Most of these healthcare providers said the test results changed some aspect of the patient's care, such as screening tests offered, and medications or dosages prescribed. CDC is concerned about such premature use of personal genomic tests by consumers because these tests are not "ready for primetime."

Despite the many exciting advances in genomic discoveries for common diseases, there is quite a bit we don't know about how to use this information to improve health and prevent disease.

So why aren't personal genomic tests ready for primetime?

There are 3 key factors that must be considered in the development and evaluation of genetic tests in clinical practice. First, there is the test's analytic validity, which is the test's ability to accurately and reliably measure the thousands of genetic variants on these tests.

In many cases, personal genomic tests do meet quality standards for laboratories. Generally speaking, the analytic performance is expected to be good, although this is not routinely monitored and evaluated systematically by independent or oversight groups.

The second thing we have to look at is the clinical validity of these tests, which is the ability of the test to detect or predict particular diseases and health conditions. This is the area for which the data are in so much flux right now.

For most diseases, we are still at the early stages of identifying the full list of genes that are associated with a particular disease. Most common diseases, as a matter of fact, like diabetes, cancers, and heart disease, are caused by multiple genes and interactions with environment and behavior. More research is needed to identify the full list of variants and how they influence disease susceptibility.

So far, a simple knowledge of family history for disease seems to be a more important risk factor for most common diseases. Genetic variants associated with diseases that have been identified so far typically account for only a small fraction of the measured impact of family history. Therefore, there is a lot of uncertainty about the risk estimates given by these tests; the estimates could rapidly change and [estimates] also vary by patient characteristics such as age, race and ethnicity, and environmental and lifestyle factors.

Finally, there is the most critical issue of the test's clinical utility, which addresses the question of: if a patient is found to be at increased or decreased risk for a disease, what can be done about it? In this area, there is virtually no information available that looks at the health implications of communicating genomic information and the balance of benefits and harms for using these types of tests.

Furthermore, many of the common interventions, such as smoking cessation, weight loss, increased physical activity, and blood pressure control, are beneficial for preventing and controlling many diseases, regardless of a person's genetics background.

So what advice should providers offer patients?

First, discuss with patients the limitations of personal genomic tests. These tests are not ready for routine use in clinical practice because of their limited clinical validity and clinical utility. Second, encourage patients to collect and keep an updated family health history. Family health history is a very informative and inexpensive "genomic test" that can be used right now. It reflects genes, behaviors, lifestyles, and environmental factors that are shared among relatives..

Family health history can help healthcare providers assess the presence of many genetic conditions and whether patients and their relatives may have an increased risk for specific diseases

And lastly, use the discussion of personal genomic tests and family history as a teachable moment to encourage patients to improve their health. We can reinforce the value of simple health promotion and disease prevention messages about increased physical activity, avoidance of cigarette smoking, improved diet, as well as adoption of medical screenings to help lower risk for specific common diseases regardless of genes.

The promise of genomics in the practice of medicine is great and exciting, but today the use of personal genomic tests is still not ready for prime time.

Thank you for your attention.


 

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