NEW YORK (GenomeWeb News) – A new paper is cautioning against an overzealous, premature adoption of new genetic tests.
University of Exeter medical professor David Melzer and his colleagues wrote a critical analysis, published online in the British Medical Journal today, calling for more research to determine the clinical relevance of genetic tests, as well as better education about — and regulation of — the tests themselves.
“Much more work is needed … to define the clinical relevance and value to patients of testing for these new genetic markers,” the authors wrote. “It is worrying that in the absence of this knowledge, commercial genetic testing services are being marketed directly to the public.”
The paper follows an opinion article published by US researchers in the New England Journal of Medicine in January, which similarly argued that physicians and the public will not be ready to deal with the implications of consumer genomics until more clinical studies are performed.
Although the authors of the BMJ article praise the robustness of the latest genome-wide association studies, which are “robustly designed” and “thoroughly replicated,” they suggest that more research is necessary to get to the bottom of most diseases. They point out that many of the variants identified are moderate or low risk — not to mention difficult to tweak apart for most complex, polygenic diseases. In addition, they noted that most recent, SNP-centered research neglects more complicated genetic variations such as deletions, insertions, or copy number variants.
“Although major scientific progress has been made, clinical applications are still mostly unclear,” Melzer and colleagues wrote.
They suggest that, at this point, the key value of genetic markers may be in providing clues about disease mechanisms. On the other hand, they argue that few of the current markers will be useful diagnostically, particularly those associated with moderately increased risk and/or with conditions for which no preventative interventions are available.
For instance, they point to a genetic variant — identified 15 years ago — that increases Alzheimer’s risk by about 14 times. “As preventative interventions do not exist,” they wrote, “debate has focused on diagnostic uses, but even this marker is generally seen as too weak for use in diagnosis.”
Finally, they warn that for some conditions in particular either false positive or false negative tests can have devastating consequences for patients.
“Onlookers may view most of this activity as genetic astrology, producing entertaining horoscopes. Unfortunately, in areas such as pharmacogenetics misleading results could trigger erroneous treatment and involve major hazards,” they wrote.
Among their other concerns, the authors highlighted the need for strong regulatory oversight of genetic tests, tests based on empirical evidence, and public and physician education based on sound and transparent information.
In an editorial in the same issue of BMJ, Tom Walley, the director of the UK's National Institute for Health Research's health technologies assessment programs, suggested genetic and other diagnostic tests should be evaluated within a basic framework that assesses both analytical and clinical validity as well as clinical usefulness and ethical concerns.
“Clinical usefulness should be the most important factor when deciding whether or not to adopt a test. But this is the least likely domain to be evaluated,” Walley wrote. “Such rigorous evaluation is not possible or necessary for all tests, but only for those that might lead to major changes in a care pathway and possibly substantial gain for patients.”
Still, both Melzer’s group and Walley suggest that the advent of genetic testing presents an opportunity to improve clinical testing in general. “Genetic tests create particular concerns, but they may provide the stimulus to develop a better framework for evaluating and regulating all laboratory diagnostic testing in the public and the private sector,” Walley wrote.