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The ever increasing tide of genetic tests aimed directly at consumers is causing increasing concern amongst scientific and medical experts, who believe that the clinical validity and clinical utility of many of the tests have not been properly evaluated.

 

This increase is at least partly due to the publication of more and more genome-wide association studies, which are steadily uncovering genetic markers for numerous complex diseases [Baker, M. (2008) Nature 451: 516-518]. At least 27 web-based companies now offer genetic tests directly to consumers, offering around 1,400 different tests [Schmidt, C. (2008) Nature Biotechnology 26: 145-146] ranging from single diagnostic tests for rare, inherited monogenic disorders to multiple susceptibility tests for dozens of complex diseases. It is this last set of predictive tests from genome-wide scans that has caused both the most excitement and the most concern; some of the associations are considered by many to be statistically unsound, and the clinical validity entirely unproven. In addition, the utility of the tests, in terms of how the results can be used to improve health, has not been established and in many cases is entirely uncertain. Many people are asking what is the use of having a test to establish a relative risk of developing a disease such as Alzheimer’s, if we can neither predict whether an individual will actually develop it, nor can we prevent, delay or cure the disease? [Couzin, J. Science (2008) 319: 1022-1023] The psychological effects of ordering a whole genome scan over the internet – and subsequently receiving rather variable levels of information regarding your relative risk of developing various devastating diseases – remain unclear, but are certainly providing interesting fodder for journalists across the globe (see The Times, 1st Mar 2008).

 

Currently, there is no formal evaluation framework or coherent regulation for genetic tests that are sold directly to the consumer and do not claim to make a diagnosis. Although the analytical validity of the test must be adequate, there is no requirement for manufacturers to prove clinical validity or utility of the tests. Experts are worried that not only the public, but also many medical professionals, do not know how to interpret these predictive tests. As the dangers associated with invalid tests are being realised, efforts are ongoing around the world to change the regulatory situation. In the US, the Food and Drugs Agency (FDA) is likely to play an increasing role in genetic test oversight, though the exact details are still being worked out. “There is a major gap in the oversight of genetic tests when it comes to evaluation of clinical validity” said Dr Reed Tuckson, chair of a US Department of Health and Human Services advisory panel tasked with drafting a better model for genetic test oversight, adding “we find that unacceptable and it has to be fixed” (see Medical Devices Today, 25th Feb 2008).

 

Comment: Earlier this year, the PHG Foundation co-hosted an expert Diagnostics Summit with the Royal College of Pathologists, to address some of these issues and discuss how laboratory diagnostic tests for complex biomarkers should be evaluated. The report and key recommendations from this meeting will be published on Tuesday 11th March 2008, and will be available to download from our website.