Taking your genes in hand

Personal genetic testing is advancing rapidly. But beware of overselling

GENETIC testing promises a lot. In particular, it promises to tell people things ranging from their risks of developing ailments as diverse as heart disease, cancer and autism to how much coffee they can safely drink. It also promises a lucrative market for those doing the testing. Single-gene tests, such as those for particular forms of genes that predispose people to breast cancer, have been available for a while. This year, however, has seen the arrival of commercial versions of techniques that can sample a person's entire genetic make-up, and do so in a way that will enable him to benefit from future discoveries as well as existing knowledge.

In many cases, knowing the risk will also allow (and might, indeed, encourage) someone to modify his behaviour to avoid a disease he is at risk of—or, failing that, to mitigate its consequences. Nevertheless, concerns are being raised about the accuracy of some tests now on the market, and also their usefulness when the results are supplied direct to consumers, rather...