3 August 2009
Appeared in BioNews 519People who have had their genome scanned to find the relative risks of them developing common genetic disorders may find themselves more or less at risk now than when they had the test done, even if thier lifestyle hasn't changed. This is due to more discoveries being made in the genetics field, and since it is often not understood by the individual, has resulted in calls for tighter regulations for the testing.
Personal genomics firms calculate the health risks of individuals based on their genetics by scanning their genome for up to one million SNPs, which are associated with genetic diseases. One such company is deCODE Genetics of Reykjavik, Iceland, which offers a personal genomics service called ‘deCODEme'. As more studies are done that find links between SNPs and diseases, the original information given to the individual may change or skew, without the person doing a thing.
In a study for the New Scientist led by Cecile Janssens, an epidemiologist at Erasmus University Medical Centre in Rotterdam, the Netherlands, information was gathered about gene predictions for type 2 diabetes in Europeans from deCODE. Since the company began its deCODEme scan in November 2007, updated research means that the number of SNPs upon which an individual's risk of developing diabetes is based has risen twice, from eight to 15 SNPs.
Using this information, Janssens and colleagues calculated how the predictions given to 1000 simulated populations of people with different SNPs would have changed after the updates of SNPs. After the first update, over 11 per cent of people went from being told they were at an above-average risk to a below-average risk, or vice versa. After the second update, over ten per cent were also reclassified.
The impact of these shifts could be that people become cynical about the value of the predictive tests, and Janssens thinks that they might lose motivation to change their lifestyle: ‘they will say: if it may change over time without me doing anything, then why should I bother?'. Michael Christman, president of the Coriell Institute for Medical Research in Camden, New Jersey, is running a study to test the clinical value of genome scans, and agrees that ‘people are likely to be confused'.
In the UK, to avoid this confusion two suggestions have been raised in the House of Lords report on genomic medicine. Firstly, there should be tighter regulation on which SNPs are included in the tests, to make them more reliable for the subject. Secondly, healthcare professionals and gene-screening companies should be better equipped to help people interpret their results, understand the limitations of the screens and focus on the most meaningful parts of their read-outs. In the UK, this might mean a change in the way NHS staff are trained.
In the US, the American College of Clinical Pharmacology (ACCP) has called for similar tighter regulation of direct-to-consumer advertising of genomic testing. They have concerns over the future of pharmacogenetic testing due to the potential public distrust of the tests, which may develop as a result of bad experiences. It is suggested that the Food and Drug Administration should have oversight in controlling advertising of the tests, as they do with prescription drugs.