WHEN an obese man with a family history of goes to see his doctor, he will undoubtedly be told to lose weight to minimise his chances of becoming diabetic. Too often, this sound but familiar advice falls on deaf ears.
Now show the same patient a printout revealing that his genes make him unusually susceptible to diabetes, and the picture changes. That information is novel, personal and somehow seems more 鈥渟cientific鈥� 鈥� and therefore authoritative. Suddenly the patient has a new motivation to eat less and exercise more.
If genome scans can motivate people to do what they ought to be doing anyway, that鈥檚 all to the good. But as 快猫短视频 has noted before, the risks associated with genetic tests are not always easy to understand (6 October 2007, p 8).
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In the case of type 2 diabetes, for example, the heritability of the disease is around , which means that environmental factors such as diet and exercise are more important than genes in . Moreover, the genes that have been discovered up to now account for only a fraction of that known heritability.
Understanding such wrinkles is important when trying to interpret a genetic scan, and to make matters worse our knowledge is changing all the time. An analysis carried out for 快猫短视频 illustrates how the risks predicted from an individual鈥檚 genetic profile can fluctuate as new discoveries emerge (see 鈥淕ene discoveries dramatically alter disease predictions鈥�). Such shifts create the danger that people will become cynical about the predictive value of genetic information.
鈥淭he risks predicted from people鈥檚 genetic profiles can fluctuate as new discoveries emerge鈥�
To prevent this happening, gene-screening companies and healthcare professionals who find patients turning up clutching their genome read-outs need to ensure that early adopters understand the present limitations of genetic scanning. They should also think about how best to help people focus on the parts of their read-outs that are most meaningful.
As a rule of thumb, medical geneticists reckon that it is worth paying serious attention only when your genetic profile suggests a relative risk for a common disease of around 1.8 or above (where 2 means double the average genetic risk) 鈥� and then only if there is something that can be done to mitigate that risk.
People buying genome scans need to understand that the results are a work in progress, and that they should concentrate on the largest risks that are unlikely to evaporate as new genetic discoveries come along. If that happens, personal genomics could become a useful tool to improve public health. It would be a great shame if that promise gets lost in a cycle of hype, confusion and cynicism.