The NHS is having to ‘pick up the pieces’ of growing use of cheap genetic tests, doctors warned last night.
Popular DNA tests – which are widely available in pharmacists and online – can easily be misinterpreted, experts said.
A panel of experts from Southampton University, Exeter University and Southampton Hospital said ‘direct-to-consumer’ genetic tests are unreliable and leave people confused and uncertain.
Writing in the British Medical Journal, they said genetic information is complex and even if people are shown to be at risk they need carefully walking through the results by a doctor – not left to panic at home.
The writers, who include Professor Anneke Lucassen, president of the British Society for Genetic Medicine, said these tests should ‘absolutely not be used to inform health decisions without further scrutiny’.
Popular DNA tests such as those made by ’23andMe’ can easily be misinterpreted, experts said
Consumer DNA tests arrived in Britain in 2014. The first test to arrive – a £79 spit test made by 23andMe – offered users the chance to discover where in the world their ancestors came from, and how their DNA influences their facial features, taste, smell and other traits.
For £149 it also offered a ‘health predispositions’ service, telling people how their genetics could raise their risk of type two diabetes, cancer, Alzheimer’s and Parkinson’s.
Other similar tests have followed, made by companies such as Orig3n, Vitagene and Lets Get Checked.
But Professor Lucassen, professor of clinical genetics at the University of Southampton, said this data is very hard to interpret.
False positives – where results indicate a person has a high genetic risk of a disease or condition when they do not – are common, she said, while false negatives may ‘reassure’ at-risk people that they have little to worry about.
‘Genetic tests sold online and in shops should absolutely not be used to inform health decisions without further scrutiny,’ Professor Lucassen said.
‘Finding a “health risk” via these tests often does not mean a person will go on to develop the health problem in question, while “reassuring” results might be unreliable.’
Among the problems she has seen in recent months include people wrongly informed by these results that they have faulty genes which suggest a high risk of certain cancer, she said.
‘I do understand that people might be drawn to direct-to-consumer genetic testing in the hope that it will provide clear cut information about their future health.
‘However, the interpretation of genetic data is complex and context dependent and genetic tests might report false positive and false negative results which can mean the correct medical steps aren’t taken.’
She said NHS doctors are often left to ‘pick up the pieces’ of flawed results.
Professor Helen Stokes-Lampard, chair of the Royal College of GPs, said genomic sequencing data has ‘huge potential’ but that healthcare professionals and the public should exercise caution.
‘The college has already voiced concerns about the increasing availability of commercial genetic tests – firstly, because the results could cause undue worry or inappropriate reassurance for patients, and secondly because of the workload implications in general practice,’ she said.
‘Genetic testing shouldn’t simply be done to satisfy a patient’s curiosity about their health as the results could have very real implications.
‘But as it stands, we don’t have the expertise to interpret them in a sophisticated enough way to be of great benefit for our patients.
‘Our members have reported patients coming to see them with the results of commercial genetic tests, asking for them to be interpreted – and some commercial companies actually advise this instead of providing the necessary advice and feedback themselves.
‘But GPs and our teams are already working under intense resource and workforce pressures – with patients waiting too long for a routine appointment as a result – so this is not a good use of our time or NHS resources, and should be the direct responsibility of the companies that are being paid to perform the tests.’
A 23andMe spokesman said: ‘Our testing process is extremely accurate – in fact we’ve proven our test to be over 99% accurate as compared to Sanger sequencing, the industry gold standard, and over 99% repeatable and reproducible, per the FDA review process. We are very clear with customers that we test only for certain genetic variants, for example, in the case of our BRCA1 and BRCA2 (Selected Variants) report these are some of the most well-studied variants, associated with extremely high risk, and we strongly recommend customers should not forgo any recommended testing based on 23andMe results.
‘The benefit of a screening tool like 23andMe is identifying risks for people who may not qualify for clinical testing. For example, published research shows as many as 50% of BRCA1 and BRCA2 carriers, which conveys high risk for breast and ovarian cancer, would not qualify for clinical testing. Our own research shows a large number of BRCA carriers in the 23andMe database who may not qualify – either based on their ancestry or family medical history – for clinical screening. These individuals likely would not be clinically tested and would otherwise not know of a highly increased risk for cancer were it not for 23andMe.
‘Furthermore, as part of the FDA review process, we proved consumers could accurately understand our health reports – including what a ‘0 variant’ result meant. A demographically diverse population study demonstrated a 90% or greater user comprehension.
’23andMe is not a diagnostic test, which is stated quite clearly throughout our reports. 23andMe is a screening tool for certain genetic health conditions, if an individual has a family history of a medical condition or other indications for clinical testing we always recommend consulting a health care provider first. 23andMe results can and do facilitate valuable conversations with health care providers. In fact we’ve had many cases where customers have taken a 23andMe result to their doctors, been prescribed confirmatory testing and have had preventative treatment as a result.
‘Lastly, we do not recommend seeking third party interpretation of 23andMe data as we cannot guarantee the accuracy of third party analysis.’