‘DON’T BOTHER WITH AT-HOME DNA TESTS’

Doctors are calling for a crackdown on genetic testing kits online as the results are misleading. Dr C strongly agrees

Not all gene testing is bad. Drug sensitivity tests that show which medicines work best for people can be helpful, which is why the NHS is investing in them. At-home DNA tests, however – where you spit on a stick, send it off and get told which diseases you’re likely to get – are shockingly unreliable.

FALSE RESULTS HAPPEN

Women have booked elective mastectomies having been wrongly told they carry the faulty BRCA gene – which raises risk of breast and ovarian cancers. Women are regularly being incorrectly told they carry dangerous mutations linked to cancer, while others were wrongly given the allclear. Wondering why? One of the most popular tests only screens for three specific genetic variants, which are most common in people of Ashkenazi Jewish heritage. There are thousands of other genetic mutations they don’t test for, so nearly 90 per cent of people with the faulty BRCA gene would be missed. Also, the science is changing all the time, and the database they use to analyse the genes is out of date, plus people can download their results and pass it on to third-party companies who are getting it wrong. Research shows that about 40 per cent of the results from these tests are inaccurate – but if you’ve read scary results, the psychological damage is already done. You’ll never trust a test again.

LIFESTYLE IS KEY

Your lifestyle has a massive impact on your cancer risk. If you were genetically predisposed to skin cancer, but wore SPF50 every sunny day and always went in the shade between

11am and 3pm, the likelihood of you getting the disease would be tiny thanks to your choices. Your family history is also more reliable than a test – if your mum, sister, aunt and grandma had breast cancer under 50, that would make you far more likely to have it too. You don’t need an at-home test to tell you that, and a doctor can carry out an accurate test to check.

The NHS has specific people whose entire job is to explain genetics, what they mean, whether people need to test for certain things, and what the results mean – a genetic counsellor. That’s how complex genetics are, so the chances of you being able to interpret results from an online report are small. I fully support the NHS using genetic testing to develop better treatment, but at-home tests are, at best, unreliable and, at worst, downright dangerous.