You may have read an article over the weekend in the Guardian on senior doctors calling for a crackdown on home-testing genetic kits, after women were incorrectly informed that they had faulty BRCA genes, which convey a high risk of breast and ovarian cancers. Science Correspondent Hannah Devlin says that “One patient was scheduled for preventive breast-removal surgery after a consumer genetic test suggested she had a BRCA mutation. The surgery was called off at the last moment when an NHS laboratory revealed the result to be a false positive.”
The ‘red herring’
A few months ago, HDR UK Rutherford Fellow, Dr Mwenza Blell, wrote a review article on a similar topic: Direct-to-consumer genetic testing’s red herring: “Genetic ancestry” and personalized medicine. She and her co-author, M. A. Hunter, explored how far direct-to-consumer genetic ancestry testing can be used in healthcare. There are over 200 direct-to consumer genetic testing services for determining ancestry – including 23andMe, Ancestry.com etc. Many of us will know someone who has used their services. But are the methods they use robust? Are the results accurate? Is there a standard definition of ‘ancestry’? Can ‘genetic ancestry’ contribute to personalised medicine to tailor healthcare?
Some tests already output ethnically-specific disease risk estimates for consumers based on their own ancestry test results, and in the US the FDA has already approved one direct-to-consumer genetic test as a medical device. Despite this, Blell and Hunter found evidence to argue against the integration of commercial genetic ancestry test results into healthcare because of the risks to patients – risks that stem from the invocation of poorly operationalised concepts that misrepresent the accuracy and validity of these tests.
The missing diversity in human genetics
This is not to say that no genetic traits which vary between different ethnic groups are relevant to health. Scientists are increasingly recognising the importance of people from diverse backgrounds participating in health research, as our Director, Andrew Morris, blogged a few months ago: The missing diversity in human genetics: a telling lesson for health data research. However the level of scientific rigour underpinning direct-to-consumer ancestry tests is arguably not currently sufficient for the results to be used to direct healthcare. In fact Blell and Hunter argue that health regulators the world over should think carefully about approving commercial genetic tests as medical devices. They recommend that the professional bodies of clinical practitioners (e.g. American Medical Association, the Royal College of Physicians in the UK) and agencies evaluating medical devices (e.g. FDA, European Medicines Agency) examine the evidence discussed in their paper and consider issuing specific guidance or warnings about use of genetic ancestry test results in healthcare since these are not suitable for diagnostic purposes and pose risks to individuals and society.
The link to HDR UK Science Priority: Understanding Causes of Disease
Understanding Causes of Disease is one of Health Data Research UK’s six Science Priorities, and is led by Professor John Danesh, of the University of Cambridge. It will use health data in its multiple forms to understand the causes of disease and discover new targeted treatments rather than just addressing symptoms. Blell and Hunter’s paper demonstrates that using direct-to-consumer ‘genetic ancestry’ testing has a long way to go before it can reliably inform personalised medicine, if at all.
This blog is based on the publication, Blell M and Hunter M. A. (2019) Frontiers in Medicine, 6:4.
Dr Blell is a HDR UK Rutherford Fellow based at Newcastle University and works on socially-relevant issues in participation with communities and relevant healthcare stakeholders to enable co-production of health-data infrastructures which are socially responsive and responsible.