I can easily see a layperson reading that, and thinking "warfarin sensitivity"? As in "food sensitivity", meaning "this is something that isn't good for me, and I should avoid it?" Wait, isn't that the stuff that gave my grandmother a stroke? Holy shit, they killed my grandmother by giving her too much of a medicine that she's sensitive to!"

All warfarin sensitivity actually means, though, as far as I understand it, is that you're likely to need a lower dose than the average patient. If your grandmother had a stroke, it's unlikely that she was overdosed, though - in fact, it's quite likely that she received too low a dose.

If someone has a stroke under warfarin treatment, there are two likely causes: Either their warfarin dose was too low, or they had an artery-to-artery embolic stroke instead of the cardioembolic stroke the warfarin was supposed to prevent. (There are of course other, more rare cases of stroke, but those are the two big ones.)

Do you see how there's a huge potential for misunderstandings here? I'm not saying you suffered this particular misunderstanding, or that laypeople should be stopped from getting this information. I'm just saying, if you're going to put something like that out there and claim it's a diagnostic tool, it needs to be accurate and it needs to be explained, and that's where the FDA needs to come in.

In fact, just last month, the New England Journal of Medicine published a landmark study around the pharmacogenomics of warfarin dosing, which found that this very genetic data does NOT affect/improve warfarin dosing (http://www.nih.gov/news/health/nov2013/nhlbi-19.htm, original paper: http://www.nejm.org/doi/full/10.1056/NEJMoa1310669). In light of this, this warfarin sensitivity information that you've obtained from 23andMe is almost certainly a false positive, and if you were on a prescribed warfarin treatment, 23andMe would've likely resulted in a change in your behavior that would be strictly detrimental to your health.

I don't think there is any valid basis for that claim. A rational person (and I only mean "somewhat rational", I'm not talking about an Econ101 "perfectly rational actor" here) would get their 23andMe results, go "hmmm, this is interesting" and line up a visit to their primary care physician to talk about the results, and what it might mean for their treatment... at which point additional tests might be indicated, or the doctor could more fully explain the various tradeoffs, implications, etc.

There's no particular reason to assume that people are going to randomly adjust their medications based on 23andMe results alone.

And, even if they do, so be it - the price of personal freedom is individual responsibility for the outcome of your actions.

This appears to be more a political issue than a scientific one.

They can't have it both ways. They can market and dump out your DNA data. Or they can meet regs, prove they are clinically accurate, then market it as a diagnosis product.

We'd not like random companies starting up and misleading people and claiming to diagnose but really just flip a coin. That's all the FDA is asking.

If they want to sell DNA dumps and call them DNA dumps, that'd be truthful advertising. But if they want to make diagnostic claims, they need to actually back them up.

That's the point. If they simply gave people raw results and told them to Google it, that'd be fine. They could even provide a report with hyperlinks to SNPedia. But that's not a very fun marketing message, is it? 23andme wants to sell itself as accurate diagnosis, without having to actually prove they're accurate. The FDA's letter said the FDA tried to contact them repeatedly about this issue, asked them to change language, and 23andme ignored them. What's the FDA supposed to do?

They should crawl back into their bureaucratic cave and carve some hieroglyphics into the walls with pieces of flint, or otherwise find some way to occupy themselves while the world goes on quite well without their unnecessary interventions.

I'm no expert, but it seems like the validity of these tests are being drawn into question. While it may help, it may also really hurt. Questioning these interpretations is exactly what medical science should be doing. You're not getting information about yourself, you're getting (to you) incomprehensible data and a guess as to what it means. Is that more valid than the family history that your doctor already has?

Humans tend to make emotional decisions when it comes to their own health. The goal of medical science is to get past the emotion (look at what this drug did to my grandma) and find provable facts instead.

Then you repeat the test. Your doctor may not have been considering that you may have a warfarin sensitivity, the doctor's family history may be incomplete, etc. etc. This is especially an issue with minority communities, whose medical issues are not as well dealt with by physicians, or medical science in general (minority = fundamentally less statistical strength). It's not a well-known fact, for example that asians tend to have statin sensitivity because of impaired clearance, a lower dose is equally effective in asians (although IIRC while effective in reducing cholesterol, endpoint efficacy of statins in preventing coronary disease is unknown in asians); to my horror I found my father was being prescribed the 'caucasian' dosage of statins, and then a year later, I took the 23andMe test and found that I'm homozygous to a codominant allele that is associated with dramatic increase the risk of myopathy when taking simvastatin. So here my dad is taking an inappropriate dosage of a drug that is likely making him sicker and maybe not even helping prevent coronary disease.

Now, the question you have to ask yourself, is, is it worth it to deny responsible people like myself the power to easily and cheaply obtain these sorts of decisions just to protect people who are going to get hysterical about information, even when there's a second layer of professional expertise that intervenes before any medical action is taken?

look at what this drug did to my grandma

But that is exactly, scientifically valid evidence. I think you are placing an unreasonable reverence on the 'validity' of medical 'facts' or the competence of medical authorities. After all, proper scientists aren't necessarily seeking provable facts but rather, disprovable assertions.

And this is exactly the sort of crazy nonsense that happens when you give medical information to laypeople without explaining it properly. Warfarin doesn't cause strokes, or if it does, it does so as a crazy and crazy unlikely side-effect in a vanishingly small number of patients. The common, dangerous, life-threatening side effect of Warfarin, the one you need to be worried about with a Warfarin sensitivity, is bleeding. Of course, Warfarin, when administed in a careful, low dosage to people with the sensitivity, may fail to prevent a stroke, but Warfarin almost certainly did not give the previous commenter's grandma a stroke, and it's driving me slightly crazy that this thread is causing people to think that it's some sort of common side effect.

What if the test is inherently flawed?

"look at what this drug did to my grandma"

Uh, that is purely anecdotal, n of 1 data, which is not scientifically valid evidence. This is what scientifically valid evidence begins to look like: http://www.nejm.org/doi/full/10.1056/NEJMoa1310669, which suggests the _opposite_ of what 23andMe says about warfarin sensitivity.

The point isn't that we shouldn't have tests for things such as warfarin sensitivity or statin sensitivity; it's simply that we need to have clinically VALIDATED tests for these medical conditions. Otherwise, without a clear understanding of the analytic and clinical validity of these tests, it's possible that many false positives or false negatives arise.

There's a reason why other genetic tests (e.g. Genomic Health's Oncotype DX or Myriad's BRCAnalysis) haven't been pulled by the FDA (in fact, they're not even regulated by the FDA!) - that's because they've gathered sufficient data to support the clinical outcomes and utility claims that they've made. Put more simply, these other molecular diagnostics have actually verified their science. 23andMe has not - that's why they're being regulated.

None of this DNA testing stuff is super-accurate.