Commercial genetic tests, often advertised as capable of predicting an individual's susceptibility to life-threatening diseases, are a 'waste of money' and their results may cause excessive anxiety or falsely assure consumers about whether they are likely to suffer certain medical conditions, warn UK genetics experts.
The availability of personalised DNA analysis for common diseases over the Internet for more than £500, typically for heart disease, Alzheimer's disease and cancer, has dramatically increased in the past year. However, experts caution against many of the tests, because they are not regulated for scientific or clinical validity and often don't provide additional information above that revealed by taking a patient's family history. Other tests, according to Professor Shirley Hodgson, an expert in cancer genetics at St George's University of London, merely provide generically good advice to eat healthily, not smoke and exercise.
Next week, the UK's Human Genetics Commission (HGC) will issue a report requesting tighter regulation of predictive genetic tests, including independent evaluation to substantiate claims before marketing. This follows the HGC's earlier report recommending that tests should only be available via doctors and, like prescription medicines, should not be advertised directly to the public.
Scientific understanding of the genetic causes of common diseases continues to rapidly advance, but commercial tests often test for only one or two gene variants when actually multiple, interacting genetic variations are thought responsible for many diseases, said the experts. Also, the crucial impact of lifestyle and environmental factors remains largely unknown. Dr Paul Pharoah, senior clinical research fellow at Cambridge University Cancer Centre explains, '...we only know about a handful of genes. But the likelihood is there's hundreds of genes for every disease'. He views counselling individuals on how to modify their lifestyles according to these test results as 'effectively ludicrous' and 'bad science'.
Stuart Hogarth, from the Institute of Science and Society at University of Nottingham explained that genetic tests are considered 'low risk' so the governing EU directive does not require them to be reviewed before marketed. Thus, there is no obligation for companies to prove their claims or provide appropriate genetic counselling. Many sites inaccurately imply approval from professional societies. 'We have no way for consumers to separate good tests from bad tests and there is a severe danger of losing public confidence in what is a very promising...area of science...' Consumers should be 'sceptical', said Hogarth. The HGC supports re-classifying genetic tests as 'higher risk' to attract greater controls.
Sources and References
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Genetic risk tests 'waste of money'
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Can a gene test predict the future?
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Genetic testing for diseases 'a waste of money'
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