single nucleotide polymorphism SNP
The company 23andMe provides personal genetic testing from a convenient home saliva sample kit. Their home page indicates that their $99 genetic screening will provide reports on 240+ health conditions in addition to giving you information on your genetic lineage. The benefits, they claim, are that you will learn about your carrier status and therefore the risk of passing on genetic diseases to your children. The information will also inform you about health risks so that you can change your behavior to manage them. Finally the genetic information will tell you about how you might respond to different drugs so that you can “arm your doctor with information.”

The home page also contains a link to testimonials about how their DNA testing has changed people’s lives.

This all sounds great – the promise of genomics that we have been hearing about now for about two decades. Isn’t this exactly what we were led to expect once we mapped the human genome?

Why, then, has the FDA recently sent a warning letter to 23andMe instructing them to discontinue marketing their Personal Genome Service (PGS)?

The primary reason appears to be a lack of documentation for the validity and reliability of the tests, but I have concerns that go even deeper.

The FDA is concerned mostly with whether or not the genetic testing offered by 23andMe works as advertised. False positive and false negative testing could have significant medical consequences. The company is marketing its PGS specifically to aid in medical management, including drug management. Despite the fact that the website says “arm your doctor,” the FDA fears people will use the information to self-manage, for instance by adjusting their own dose of critical medication.

The FDA is also particularly concerned about genetic tests such as those for BRCA, which conveys risk for breast and ovarian cancer.

In other words, there are serious medical consequences to the genetic information being provided by 23andMe and they have not performed the due diligence required to make sure their tests are valid and reliable. The FDA letter documents their attempts over the last five years to work with the company to help them come into compliance, but to no avail.

I can only speculate that the company is not complying with the FDA because they cannot – they do not have the scientific information the FDA requires and they are dragging their heels on producing it. They may simply be trying to avoid the cost of such research, and hoping the FDA will eventually back off (perhaps they were hoping to hold out for an administration change). The FDA, however, is being tenacious.

I certainly like to see the FDA aggressively doing its job of protecting the public from unsubstantiated health claims and from products and services that are not adequately backed by scientific studies and proper quality control. The public expects that this is the case.

However, I also always marvel at the irony such cases highlight. Articles discussing this and similar cases often include quotes such as the following:

“Our society regulates medical products to protect public health. Without strong public oversight, we’re back to the era of snake oil,” said executive director Marcy Darnovsky. (of the Center for Genetics and Society)

I completely agree. Now let’s talk about the entire homeopathy industry, the lack of even basic quality control in the supplement industry, and the pathologically false health claims routinely made within the world of CAM (complementary and alternative medicine).

While I agree with the FDA going after 23andMe for noncompliance, I have to wonder why it has picked this company out of all the possible targets out there. I know that much of it has to do with their regulatory scope. They cannot take on homeopathy, for example, without Congress changing the law. But I can think of many other suitable targets that seem to be getting a free pass. Perhaps it simply comes down to the fact that they are not adequately funded to do their job given their regulatory limitations.

As I alluded to above, I have issues with personalized genetic testing that go beyond the stated concerns of the FDA. Even if the company provided data showing that its genetic tests were accurate, valid, and reliable, that does not mean that they are necessarily a good idea. The deeper question is – is the information itself useful, or will it perhaps have negative unintended consequences?

We have discussed the pitfalls of screening tests on SBM before. Superficially, screening tests seem like a good idea with no downside. More information is always better, right? That is certainly the approach that 23andMe is taking (of course, their business model involves providing that information).

However, there are potential issues with any screening test. Some do relate to sensitivity and specificity – how reliable are the tests. No test is 100% sensitive or specific, which means that even very good tests will have occasional false positives and false negatives. If the entity you are screening for is rare enough, then even a very accurate test may still provide more false positives, for example, than true positives.

This issue aside, meaning even if we had a 100% accurate test, we have to ask the further question – what is the net effect of providing this information? Potential negative consequences of accurate screening information include the unnecessary worry of learning that you have a predisposition or risk of developing a disease in the future. This may seem like a small thing, but it can have a significant impact on quality of life, even to the point of people being crippled by their fear of impending disease.

Further we have to consider what, exactly, will be done with the information. The implication is that drug treatment can be modified, and risk factors for disease can be addressed. But – is genetic testing (with our current knowledge base) the best way to approach such treatment? Will the genetic information cause people to change their behavior in a way that will have a net negative effect on their health?

Such behavioral changes may also include a false sense of security in those with negative screening for certain risk factors. If someone finds that they are in a low-risk group for heart disease, will they then feel free to engage in an unhealthy diet that will still be a risk factor for them?

Screening indicating a high risk may also motivate people to seek out unnecessary health care, which may lead to unnecessary tests that have their own false positive and negative rates.

There are downstream consequences to providing health information to large numbers of people. The 23andMe website is providing only handpicked testimonials with smiling faces about how their lives were improved. We have to wonder about cases of negative effects from the information provided. The only way to know net health effects is to properly study not just the accuracy of the test, but its effect on the people who receive the results. The FDA seems concerned only about the former, and not the latter (which may be appropriate given its scope).

What we have to consider as a society is how to regulate private companies directly marketing health services to the public, bypassing medical professionals. This is part of a larger issue with the public having increased access to information in general, including their own medical information. In general I am in favor of increased information access, but we can’t do this blindly. We need to consider consequences and how to put into place systems that can help put such information into proper context and use.

For example – electronic medical records systems mean that my patients can often now directly access their test results. This is convenient, and they certainly deserve to have access to their own information. But what often happens is that the test results contain misleading noise – numbers that are just outside of the normal range, or MRI findings that sound scary but are actually insignificant. I have seen this cause unnecessary anxiety on the part of patients, and take up more staff and physician time than if the results were filtered through the physician in the first place.


The FDA’s current problem with the PGS of 23andMe is concerning, as it indicates that the company has not provided proper documentation that the services they provide are valid and accurate. There are problems with the service, however, that go deeper than simply accuracy.

Our society has increasing information and public access to information. While it is difficult for me to think that this isn’t a good thing overall, we have to thoughtfully consider the possible unintended negative consequences. This case is part of a larger pattern of sacrificing quality-control filters for the sake of open access. This increasingly puts the burden on the public to make sense of sometimes complex and technical information.
Everyone, now, can be their own geneticist.


Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.