England's Health Secretary, Matt Hancock, has been criticised by doctors for over-reacting to a DNA test he said may have saved his life by revealing a "higher risk of prostate cancer".
Some senior medics said the test had shown his risk was normal and he would be wasting NHS resources acting on it.
And GPs warned genetic test results could be "of dubious value" and leave people "unnecessarily distressed".
Others welcomed his focus on using genetic testing more widely in the NHS.
'Surprised and concerned'
In a speech to the Royal Society, Mr Hancock set out his vision for genetic testing to be made available to everyone on the NHS in order to prevent disease and save lives.
He also revealed his own genetic test results, saying he had been "surprised and concerned" to discover he had a 15% risk of developing prostate cancer by the age of 75.
Having then booked an appointment with his GP to discuss "the correct course of action", he said, he would now make sure he didn't "miss any screening appointments in the future".
Mr Hancock said: "I would never have found this out if it hadn't been for the genomic test.
"Tragically, so many men don't find out they have it [the risk], until it's too late.
"The truth is, this test may have saved my life."
But the average lifetime risk of developing prostate cancer for men born after 1960 in the UK is 18%, according to Cancer Research UK data.
Prof Anneke Lucassen, professor of clinical genetics at the University of Southampton, said Mr Hancock's claim his life had been saved by the test was "somewhat over-egging the pudding".
Leading geneticist Prof David Curtis, from University College London, went further, saying his claim was "frankly ridiculous" because far more people developed prostate cancer than actually died of it.
And Prof Diana Eccles, dean of medicine and professor of cancer genetics at the University of Southampton, called his risk "pretty modest".
"Prostate cancer is not one disease - many are indolent - and early detection means knowing about it for longer when it may never impact on life expectancy," she added.
There are also many other risk factors for prostate cancer - other than genetic ones - and there is currently no UK screening programme for the condition because the prostate-specific antigen (PSA) test is unreliable and could result in many men receiving treatment unnecessarily.
Prostate Cancer UK said there was "no clear guidance on what men should do if a genetic risk is identified - particularly in the absence of tests suitable for a prostate cancer screening programme".
"That is why we do not currently recommend investing privately in DNA tests as a first step for men concerned about their risk of prostate cancer," chief executive Angela Culhane said.
Sophia Lowes, from Cancer Research UK, said: "We'd always encourage anyone who's experiencing symptoms or something that isn't normal for them to visit their GP.
"In most cases, it won't be cancer - but it's better to get it checked out."
What are the symptoms of prostate cancer?
Prostate cancer does not usually cause any symptoms until the cancer has grown large enough to put pressure on the tube that carries urine from the bladder out of the penis (urethra).
They can include:
- needing to urinate more frequently, often during the night
- needing to rush to the toilet
- difficulty in starting to urinate (hesitancy)
- straining or taking a long time while urinating
- weak flow of urine
- feeling the bladder has not emptied fully
- blood in urine or in semen
But many men's prostates grow as they age because of a non-cancerous condition called prostate enlargement.
Signs the cancer may have spread include:
- bone and back pain
- a loss of appetite, pain in the testicles
- unexplained weight loss
Source: Prostate cancer - NHS
'Confused and distressed'
Although there is widespread agreement that genetic testing will have an important role to play in the future, Prof Helen Stokes-Lampard, who chairs the Royal College of GPs, said it had to be properly evaluated first.
"Many things that will be picked up by genetic testing will be unimportant or of dubious value and these could leave people unnecessarily confused and distressed," she said.
"This will undoubtedly lead to an increased number of worried people wanting to visit their GP to discuss their borderline results, at a time when general practice is already struggling to cope with intense demand and millions of patients are already waiting too long for an appointment."
Medical research charities said genomics offered the potential to better understand a wide range of diseases and develop new treatments.
However, Prof Ewan Birney, from the European Bioinformatics Institute, said there was more work to do first.
"The rollout of responsible use of genetic risk scores requires careful integration from genetic research to healthcare practice," he said.
A Whitehall source said: "There's never any progress that hasn't been opposed by someone, somewhere.
"Genomics has the potential to transform our lives for the better - so it is vital we embrace the potential of this new technology for the benefit of all."