23 February 2015
The British Society for Genetic MedicineAppeared in BioNews 791
The 23andMe test and other similar direct-to-consumer (DTC) genetic tests are likely here to stay. Those in favour see them as a way of engaging the public with science and making it fun, but there are problematic aspects, too. The issue of interpretation of the results is perhaps of greatest concern.
In BioNews 788, Professor Joyce Harper highlights some of the issues that the general public need to be aware of should they undertake such testing.
One would expect a professor of human genetics to come quickly to an in-depth understanding of the test and results and be able to deploy her ability to interpret findings and contextualise them. But what Professor Harper highlights is that even with an elite level of genetics knowledge she was left with unanswered, potentially anxiety-causing, questions and no professional support to rely on post-test.
And while Professor Harper understood the limitations of the mutation testing, it is unlikely that the majority of 23andMe's customers would do so with no access to advice regarding interpretation of results or what they should do after the test. As a result some may be falsely reassured by the absence of a specific mutation or overly anxious about a genetic trait which may be insignificant.
In addition, Professor Harper understood the potential impact of accessing the 'locked' results for Alzheimer's and Parkinson's disease risk and for BRCA1 and 2 mutations. Alzheimer's and Parkinson's are both serious, late-onset conditions with no preventative treatment. Such knowledge in the hands of those unprepared for a high-risk result may have a significant practical (insurance/ employment), emotional and social impact.
Some may argue that DTC tests are no different to buying a blood pressure monitor, for example. There is similar potential to discover an unexpected reading and action may be required as a result. However a blood pressure monitor gives read-outs that are easier to interpret with clear parameters for normal/ abnormal outcome. Associated follow-up is straightforward, logically progressing to a GP appointment and possible onward referral to cardiology.
Such clarity, known parameters and follow-up are not true for 23andMe results. Firstly, there is a temptation to think a genetic code read-out is clear-cut but this is a misconception (for now at least). Also we do not know when the predicted ill-health might show itself, if it shows itself at all. Secondly, Professor Harper had an increased risk of deep vein thrombosis (DVT) yet received no direction as to how much higher than average the risk would have to be before taking different action from normal. Thirdly, there is no clear route for consumers to know what to do with the information.
Professor Harper sets out the scope of the 23andMe test and its limitations and says that Next Generation Sequencing would be the preferred test for picking out a mutation linked to a genetic disorder. This is true in a proper clinical setting, but we need to remember why people will take the 23andMe test. The majority are likely to be healthy individuals who see this as interesting and engaging and may want answers to their ancestry rather than their risk for future disease. There is confusion between a 'fun' read-out (how Neanderthal am I?) and health result (the chance of developing DVT). Those who are hunting for the genetic basis of a family disorder will be in a minority, but are perhaps of greatest concern.
People in the UK who have concerns about a family history of disease or potential risk of genetic disorder can freely access advice and support from their GP, from where they may be referred on to their local NHS clinical genetics service.
There they will be fully assessed and offered appropriate genetic testing, which will be interpreted by qualified professionals. Advice in relation to the limitations of testing, follow-on health care, and the implications of results for themselves and other family members will be given.
DTC tests may be here to stay, but as they gain a foothold, professionals should highlight the uncertainties, limitations of and alternatives to such testing to potential customers.