Study Says DNA’s Power to Predict Illness Is Limited

[bemildred]

If every aspect of a person’s DNA is known, would it be possible to predict the diseases in that person’s future? And could that knowledge be used to forestall the otherwise inevitable?

The answer, according to a new study of twins, is, for the most part, “no.”

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So, the new study concludes, it is not going to be possible to say that, for example, Type 2 diabetes will occur with absolute certainty unless a person keeps a normal weight, or that colon cancer is a foregone conclusion without frequent screening and removal of polyps. Conversely, it will not be possible to tell some people that they can ignore all the advice about, for example, preventing a heart attack because they will never get one.

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“The general point is absolutely correct,” said Dr. David Altshuler, professor of genetics and medicine at Harvard Medical School, who was not involved with the research. “Even if you know everything about genetics, prediction will remain probabilistic and not deterministic.”

http://www.nytimes.com/2012/04/03/health/research/dnas-power-to-predict-is-limited-study-finds.html?_r=1&ref=dnadeoxyribonucleicacid

Edit: seen a couple of these now. The piece I just read in science news suggests that statistical probabilities are actually slightly better as a predictor of disease than DNA analysis, i.e. DNA analysis may mislead a bit.

[xchrom]

1. What I think will happen near term is a period

Where researchers start watching people day to day - compiling data and keeping that next to the DNA info.

This is an interesting time in biomedicine.

[bemildred]

2. Yes, I think detailed (and expensive) long-term "longitudinal" studies are going to be necessary.

To sort the wheat from the chaff, so to speak.

The problem is (fundamentally) that biological systems are far too large and complicated to be predictable in any mechanistic way over the long haul. Furthermore, they are not designed with some particular structure, but grown in a most complex interaction with the environment they find themselves in. Think chaos theory, biological systems are chaotic in the mathematical sense, as is much of the rest of the natural world. Predicability in the Newtonian way is exceptional, not the norm. For most things, most of the time, certainty is not to be had, and this is particularly true in biology, which is why we are so interesting.

This does not mean that there is not much to learn and do, it means you can't just sit down with some equations and a calculator and figure things out, you have to observe, and observation must guide theory, not the other way around.

But we do love our theories.