The CDC is wrong about DNA testing

Nov 17th, 2011 | By | Category: Social & Ethics

(this is a post I started 2 months ago, but is still pertinent)

Perhaps the Centers for Disease Control is not wrong. It’s an individual, Muin J. Khoury, on the CDC blog that understated the utility of DNA testing and overstated the “harm” of DNA testing and the utility of family trees. An misses a real issue with DTC genetic testing.

If though you take those points in aggregate though, the post’s thesis is wrong. If you consider that Muin J. Khoury is the director of Public Health Genomics of the CDC, the perhaps that’s about as close as you can get to the CDC being wrong. So, in short, the CDC is wrong.

Dr. Khoury’s first link is a link about privacy, a link from the  Canadian Office of Privacy Commissioner to be exact (not exactly apropos to US policy making). He doesn’t go into the issues of privacy at all though, which is the one aspect  that I think someone considering DNA testing truly must ‘think about before spitting.’ It is the one facet of this that has the most powerful ramifications that would call for careful consideration. Unfortunately, there is nothing in that post about those issues, nothing about GINA, or it’s holes. There is nothing about how different states have different laws concerning genetic privacy, nor anything about how companies are, or are not, safeguarding your privacy. Instead, Dr. Khoury brings up issues that, frankly, are overstated at best.

Harmful? Daniel McArthur already discusses this in “Willful ignorance is not an effective arguement against personal genomics” and Dan Vorhaus discussed the FDA hearings touching on this. My point concerning the latter is that it is not smart to lump the ‘snake oil’ personal genomics companies with the legitimate ones like 23andme and Navigenics as an argument that ‘personal genomics’ is harmful. Though Dr. Khoury does not say this explicitly, it is implicit in the argument.

He answers the first question “…how well can these tests detect or predict particular health conditions?” with some poorly reasoned arguments.

Most common diseases, such as diabetes, cancers, and heart disease, are caused by multiple genes and interactions with environment and behavior.  Therefore, a risk estimate based only on genes is bound to be uncertain and can rapidly change based on new information.

True, but this ignores the fact that some disease risks have a strong genetic components that are predictive (prostate cancer, etc).

Second question ” If the test indicates increased or decreased risk for a disease, what can be done about it? Will the test tell us more than what we know to do already?

Many interventions for reducing one’s risk for common diseases–such as smoking cessation, weight loss, increased physical activity, and blood pressure control–are beneficial regardless of a person’s genetic background.

True, I’ve argued this. But, this ignores again that many diseases have a strong component of environment/disease interaction (caffeine) that are very different from person to person. 1 in 100 rule. If out of 100 genes, 1 helps me to greater health.. lactose, caffien, etc.

A very informative and inexpensive “genomic test” is available right now: family health historyExternal Web Site Icon.. An accurate, updated family health history can help healthcare providers assess the presence of many genetic conditions and whether patients and their relatives may have an increased risk for specific diseases. Family history also captures shared genetic, environmental and cultural disease risk factors.

This is overstated, if not completely incorrect, as I’ve argued before.  Families of adoption have no such history to look at, Most families have poor family history records and poor environmental/cultural information across generations. Additionally, though a family history can indeed help find genetic propensities, finding them all is a difficult task to say the least. And sometimes family history fails.

This is not an argument against family health histories, but the ‘genomic test’ of a family health history is a poor  argument against actual genomic testing. In fact, in conjunction, the two would be excellent tools complementing strengths and minimizing weaknesses of both.

The short of it is that Dr. Khoury’s (and thus the CDC?) arguments against DTC personal genomics are weak at best.


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