Beware Genetic Snake Oil

How many of the 1,500 disease tests have actually been approved by the FDA?
About a dozen.

What are the implications of that?
Because most of the existing tests are for rare diseases, the public health implications are not very widespread. But as we start to test for complex diseases and have tests that are going to dictate treatment choices, those are going to have larger public health consequences. So looking to the future, it's going to be increasingly critical that we have a regulatory system in place, both to reassure investors that the regulatory climate is stable and to give doctors and patients the confidence and information they need to make really wise health-care decisions.

Unlike rare diseases, complex diseases are not one-gene disorders, right?
These are places in the genome where you tend to find a higher incidence of fill-in-the-blank disease. These "association" studies are really, really important because they are helping to identify all of the molecular actors that have a role in the play of, say, diabetes. Right now that's the big challenge for the research enterprise. To figure out which genetic molecular players are involved in the development of complex diseases.

Right now, though, scientists don't know all the genes involved in these complex diseases. So you might get tested and get falsely reassured, correct?
False reassurance is a bad thing. Let's say there's a lot of diabetes in my family. I get this test and I find out I don't have an increased risk over the general population. I'm going to be less worried, even if the test did not screen for all relevant mutations or take into account my diet and lifestyle.

You could also test positive for a complex disease and worry about a risk that's really pretty low.
If you've got an odds ratio of 1.3 and the actual risk of one person is something like one in 24,000, then your risk is insignificant. It's an insignificant finding. So what are people going to do with that? Say people get tested and they find they have a modest increased risk of developing type 2 diabetes. Let's say they fall into the same personality trait that I have, which is I worry a lot. They go dashing off to the doctor, saying, "I had my genome done and I'm at increased risk for diabetes." The doctor isn't going to know what they're talking about. And second, the doctor is going to feel he needs to do a whole lot of screening tests he wouldn't normally do. We're going to be sucking resources out of the health-care system for wealthy, worried, well people.

Are any of these tests making a positive impact on treatment yet?
It used to be you could get a test, you'd know you're at risk, and there wasn't a thing you could do about it except get depressed or go on a cruise. Now, increasingly, there are things you can do to reduce your risk. For a long time there was no good evidence to say there was anything you could do to lower your risk if you tested positive for the BRCA 1 or 2 mutation. Now it's clear that surgical removal of breasts and ovaries reduces risk. The Alzheimer's clinical trials for the drug Avandia are incredibly exciting. In an ideal world the drug will prevent Alzheimer's progression and also restore function. If you can test for Alzheimer's and know you're at increased risk and you're starting to develop symptoms, maybe one day you can take this drug.