Gene tests from shops and internet 'waste of money'

· No evidence that they work, say scientists
· Family history 'better indicator' of disease risk

A range of genetic tests sold in health shops and over the internet have been been branded a waste of money by leading scientists, because there is no evidence they work.

Gene tests claiming to measure a person's risk of developing intractable diseases such as cancer and Alzheimer's are being rushed to market even though studies to prove they benefit patients have not been done, researchers told a meeting on genomics and public health held by the Royal College of Physicians in London.

The tests differ from those available on the NHS, which generally look for single gene mutations known to cause disease, such as cystic fibrosis. The new tests are being developed to look for sets of genes scientists have linked, often tenuously, to a person's susceptibility to disease.



Dr Khoury's group recently assessed two genetic kits available in the US that claim to measure cancer risk. "Both look for more than a dozen genes, but only two genes appear in both tests," he said. "The problem is companies are taking early scientific discoveries and bundling them up into tests too quickly."

The tests have emerged because regulations only require them to be safe and measure the genes they claim to. As yet, there is no requirement for companies to prove that finding genes has any bearing on the person's future health.

The issue is highlighted by a recent announcement from Iceland that scientists had discovered a gene linked to type two diabetes and hope to develop a test. Even if such a test is made available, the advice to those testing positive will be the same as that given to all - eat sensibly and take more exercise, said Dr Khoury. "If that's the case, why buy a test?" Last year, the lobby group Genewatch complained to trading standards officers about a genetic test marketed in the UK to help smokers quit. It was developed by scientists at an Oxford University spin-out company, G-Nostics, which has since scaled back its claims for the NicoTest's benefits.

Helen Wallace of Genewatch said the number of genetic tests was likely to expand as the food industry develops them in the hope of making money from personalised diets. A report due soon from the lobby group highlights 11 genetic tests either on the market or available soon which claim to help a person tailor their diet. "What line should society take?" asked Dr Zimmern. "Should it say that if it doesn't harm you, you can allow the snakeoil salesmen? Or does society have an obligation to make sure the consumer is only buying tests that work? I think industry has to get together with government to set up studies to test whether these tests make any difference to people's health."

FAQ Genetic testing

How do genetic tests work?

Typically these are carried out on a blood sample or cells from the inside of the mouth and involve looking for mutations in the DNA that are known to cause disease.

What are the consequences of getting the wrong information?

Interpreting results can be difficult. An incorrect result can have serious consequences. A patient at low risk of a disease, but whose test result suggests they are at high risk, may adopt a fatalistic attitude, taking up high risk activities such as smoking in the belief they have nothing to lose. Alternatively, a patient who thinks they are at low risk of cancer may ignore early symptoms.

What is the alternative?

There is a lot of genetic information tied up in your family's history of disease. But many people are not aware of it or interpret it incorrectly, according to Darren Shickle, an expert in public health at the University of Sheffield.

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