California and New York regulators have been in the news lately (such as here and here), with their attempts to crack down on the nascent direct-to-consumer genetic testing industry. These states argue that companies like 23andMe, Navigenics, and several others, are offering unproven and unlicensed clinical tests directly to consumers. Are the services offered by these companies clinical tests, subject to the normal regulations of other clinical tests? Should the government be able to stop you from getting your DNA sequenced?

The answer to the second question is a flat-out no. The government has no legitimate reason to prevent you from getting genotyped. The technology used by these personal genetics companies is very good - in the future, this technology will be cheaper and cover more variants in your genome, but what is available right now is very good. And there are reasonable non-clinical reasons to get yourself sequenced, out of sheer curiosity, or for genealogy purposes, for example. More importantly, this sequence data is a permanent resource for you. Although we may not have very good clinical tests for complex genetic diseases right now, we'll have them in the future, and any DNA sequencing you get done now will be suitable for these future analyses. Once you have your raw DNA data in hand, it's there if you need it in the future.

So, as things stand now, the genotyping serviced offered by 23andMe, DecodeMe, and Navigenics have enough non-clinical use to justify themselves, and these services should not be blocked by state regulators. But simply offering people DNA sequencing is one thing - making disease risk predictions is another. When these companies market disease risk prediction along with DNA sequencing, that sounds a lot like a clinical test, one which should meet the validation standards expected by State and Federal health officials.

Take the company Navigenics for example - their home page features a picture of a father looking at his son and thinking:

I'm in this for the long run. I want to be part of all the big moments in my son's life, so I'm doing everything I can to stay healthy.

The not-so-subtle implication, reinforced by the slogan "Your genes offer a road map to optimal health", is that if you get your DNA tested by Navigenics, you will learn something about your risk for certain diseases, and be able to take action to improve your chances of good health.

This is an extremely premature claim, to say the least.

Health officials are justified in their concern over an expensive service with annual subscription fees that supposedly will "[help] you understand what your genes have to say about the future of your health, and [give] you action steps to take control of your health today - so you can have a healthier tomorrow." More traditional genetic tests (and in fact any diagnostic test), such as those for cystic fibrosis, have to meet certain legally mandated standards of validity. These standards are justified - should consumers and physicians really have to research for themselves which breast cancer tests, home pregnancy tests, or insulin measuring devices really work, and which ones are frauds? No way, which is why companies that want to sell such tests have to show that they work.

That's where the problem lies with these genetic testing companies. Let me be clear, I'm not saying that they're fraudulent, purposefully selling snake oil. They are on the bleeding edge of one field of human medical genetics that, as of yet, does not have enough predictive value to be very useful in affecting your health.

A little perspective might be helpful: when you get a genetic test for something like cystic fibrosis, or Tay-Sachs, the results will tell you, in no uncertain terms, what the risk is that your children will get the disease. If a child gets two bad copies of a gene associated with cystic fibrosis, that child is essentially guaranteed to get the disease.

By contrast, the odds ratio associated with most genetic variants turned up in genome-wide association studies is between 1.2 and 1.5. That's quite small. In fact, for many of these genetic variants associated with diabetes, Crohn's disease, or what have you, there are more healthy people walking around with that particular genetic variant than sick people. Patients with Crohn's disease may be very likely to have genetic variant X, but people with Crohn's disease make up only a small proportion of the population, and there may be many, many more people with genetic variant X who are completely healthy. So testing for X is not that useful by itself.

I'm not arguing that we will never have predictive genetic tests for these complex diseases - for many we probably will, and for others we will not. But each particular genetic variant in and of itself has only a small effect. To improve our predictions, we'll have to look for more rare genetic variants with stronger effects, or discover combinations of variants that together give you some predictive value. The science will get there, but we're still some way off.

So government regulators should let these companies sell us DNA sequencing services without restriction. But when it comes to genetic testing and counseling, Navigenics and the others need to meet the same standards that other clinical tests meet. This is an innovative, nascent industry that needs to be nurtured, but we don't do that by giving the industry a free ride on clinical testing standards.