Southampton expert says home genetic testing kits "shouldn't be used for healthcare decisions"
Professor Anneke Lucassen, a consultant in clinical genetics at University Hospital Southampton, said the NHS was often left to "pick up the pieces" of flawed results.
Known as direct-to-consumer (DTC) genetic tests, some promise insights into ancestry or disease risks, while others claim to provide information on personality, athletic ability and child talent.
"Genetic tests sold online and in shops should absolutely not be used to inform health decisions without further scrutiny," explained Prof Lucassen, who is a professor of clinical genetics at the University of Southampton and president of the British Society for Genetic Medicine.
"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 cancers.
"I do understand that people might be drawn to DTC genetic testing in the hope that it will provide clear cut information about their future health," said Prof Lucassen, who addresses the issue in a paper published today by The BMJ.
"However, the interpretation of genetic data is complex and context dependent and DTC genetic tests might report false positive and false negative results which can mean the correct medical steps aren't taken."
A false positive result indicates that a person has a high genetic risk of a disease or condition when they actually don't and a false negative result indicates a person has a low genetic risk of a disease or condition when the person actually does have it.
There is also a concern around the use of third party interpretation services, which sees consumers download and send their raw genetic data to other companies to analyse.
"There is a particular issue with third party companies re-analysing ancestry data for health purposes – this can lead to a very high false positive rate for rare genetic variants,” she said.
“The rarer the variant the more predictive about health it is likely to be, so these are exactly the results we don't want to be falsely positive.
One study found that the variants found in the BRCA1 gene through this technique were more than 90% likely to be wrong.
"With this market becoming increasingly popular, it is very important we look at how we can ensure people are properly informed about the limitations of these tests and to push for more regulation to provide standards of care."
Prof Lucassen said there should be more focus on raising awareness of the problems associated with consumer testing and providing advice for GPs and other clinicians.
"When people receive a "bad news" result from a DTC genetic test, many will turn to their GP for advice, so it is vital they take this opportunity to put the results in context for their patients," she said.
"This means discussing possible sources of error and, if appropriate, shifting the conversation from genetic risk to lifestyle changes that could help to reduce future disease risk."
She added: "However, for patients with a personal or family history suggestive of a genetic condition, GPs should refer to a hospital-based clinical genetics service even if they have a reassuring DTC genetic test result."
