Thursday, April 16, 2009

Genomic research update - we've got a ways to go.

The New England Journal of Medicine published several articles this week about the current state of research on the human genome. The articles were especially focused on whether greater understanding of the genome will lead to greater understanding of how humans develop certain diseases.

(If you, like me, need to run to the dictionary every time you hear the word "genome" to find out why it is different from "gene" or "chromosome" - here's a good link. In short - the genome is the complete set of genes in a particular organism).

Kraft and Hunter, in an article they title "Genetic Risk Prediction: Are we there yet?", state pessimistically:
We are still too early in the cycle of discovery for most tests that are based on newly discovered associations to provide stable estimates of genetic risk for many diseases. Although the major findings are highly unlikely to be false positives, the identified variants do not contribute more than a small fraction of the inherited predisposition. ...Estimates are poor predictors of risk, both in absolute terms and in relation to risk estimators that will be available when more of the remaining locus associations are discovered.
In other words, to answer their title question - no, we're not there yet. The New York Times has a great review today about the NEJM series of articles that explains this far better than I can. But, basically - researchers and drug companies thought that if we could examine the genomes of people with illnesses and compare them with genomes of people who are well, one or two genes in the genome would essentially "light up" as the key genes causing these diseases. Drugs could then be made that would alter these genetic sequences, thus curing those diseases.

Turns out we're more complicated than that - much more complicated. When one or a few genes are implicated in a disease, usually these genes can only predict the disease some of the time, for some people. There seems to be a lot more going on in our bodies besides genes in the development of a disease. AND, often, there are hundreds, instead of tens, of genes involved in a disease, which makes the development of a targeted drug really difficult.

It's very smart for these scientists to be taking a step back to think about whether or not the genomic research they are doing is going to pay off in the short run (or long run). If you look at the NEJM articles, you can see some differing of opinions - some folks sound more optimistic than others... some are wisely watching their wallets, and some are ambitiously still looking into the future.

I fear we have a long way to go.

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