Get ready for the risks of genetic testing

Editor's note: Arthur Caplan is the Drs. William F. and Virginia Connolly Mitty professor and director of the Division of Bioethics at New York University Langone Medical Center.

(CNN) -- Would you want to know your future if science could tell it to you?

Some forms of commercial genetic testing promise something like this kind of future-telling. But you need to think long and hard about peeking into your own genes to see what they hold in store for your health. It may not be so easy to cope with the bad news that could result. And it is likely that other people could know your genetic future even if you do not consent to tell them.

Let's say you send your spit (yes, spit is the source of DNA for this kind of testing) off to one of the many companies advertising direct-to-consumer genetic testing and the results showed you had a huge risk of a fatal disease.

Would that freak you out? Would you want to get this news in a letter sent by overnight mail? Wouldn't you prefer to have someone available to counsel you about what negative findings mean and what to do about them?

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There are people who say they don't need help dealing with whatever the genetic tests reveal. And a new study sponsored by one of the genetic testing companies, 23andMe, backs them up -- sort of. The study suggests most people can get bad news about their risk of getting or transmitting breast cancer to a new generation without going all to pieces emotionally.

I think the study is weak. It involved only a few hundred people who already likely knew they were in a high risk group for breast cancer. It is likely that such people who seek testing will take bad news with greater calm than would you or I if we had no expectations.

At most, the study suggests that people in high risk groups who know they are likely to get a genetic disease can handle negative health information. But it doesn't tell us much about how the average person will cope in such a situation.

Remember that genetic testing is still in its infancy.

While some commercial companies promise to tell you what is the optimal diet for you to eat or whether your kid will be a star athlete, the reality is that genetic testing is nowhere near capable of doing any such thing. The accuracy of testing depends on the disease.

Some genes when present mean 100% certainty that you will get a disease, but some raise your risk only 5%. And test predictions are based on studies of small, mainly white, American populations. Testing quality depends on the lab and that is all over the place right now. So much genetic testing is not exceedingly reliable and not always trustworthy in terms of what it means for you.

Nonetheless, finding out about health risks hidden in your genes still seems to me the kind of news that at least requires you make available a trained genetic counselor to help you deal with it.

Remember genetic testing is about risk and probabilities -- and the future is shaped by your genes and your lifestyle -- facts that counselors can help make clear. It is cheaper for companies not to have to offer counseling. But cheaper is not necessarily better if the test comes up snake eyes for high risk for Alzheimer's, Huntington's, diabetes, cancer, depression or blindness for you or your children.

Even if you think you have what it takes to absorb unexpectedly distressing results about your health without the help of a counselor or doctor, there is another reason to be wary of sending off your spit to a company touting affordable genetic testing on the Internet.

In January, a team of American and Israeli scientists showed they could reconstruct the identity of people from supposedly anonymous genetic samples using readily available databases on the Internet. Genetic hackers who get a sample of your DNA could use public databases to figure out whose genetic sample they have and then they would know all about the future written in your genes too.

Maybe people are more resilient than worrywarts like me when it comes to facing potentially upsetting revelation about their genes. Still, it does not take a lot of people actually breaking down and crying to think that competent personal counseling always ought to be an option before finding out about your genetic destiny. And given the problems inherent in guaranteeing personal privacy when it comes to cracking your genetic code, you need to be very careful where and to whom you send your DNA.

Genetic testing is a very useful new tool for helping us stay healthy. But doctors, counselors and even legislators need to get involved so that genetic knowledge can be properly understood and kept private.

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The opinions expressed in this commentary are solely those of Arthur Caplan.