Understanding genome tests: Which genes cause disease?

Genome-wide tests, which attempt to deliver a snapshot of a person’s DNA, have been in the news a lot in the last week or so -- from this report that the Pentagon might want to map the DNA of military personnel to recent research that indicates that genetic tests that are already on the market don’t seem to influence consumer behavior a whole lot.

Underlying any controversy about the wisdom or folly of delving into our genes to learn more about ourselves is a fundamental question: Are common genes the ones that dictate predisposition to disease? Or do more rare, but more powerful, genetic variations hold the key?

About a year ago, the journal PLoS Biology published a study that argued that rare variants had a larger impact on disease risk than scientists had previously thought. This suggested that studies looking at common genetic variants, which seem to present only modest increases in disease risk, might not really tell researchers much. By extension, testing kits that give consumers and others a peek at the common genetic variants in their own genomes might not tell people much, either.

Might all the effort being put into charting people’s genomes to find common markers be for naught?

This week, PLoS Biology followed up the 2010 study -- which, editors said, “generated a huge amount of controversy” -- with four new papers delving into the debate.

Two groups of scientists offered critiques -- here and here -- of the original study. That paper’s author, David Goldstein, wrote a rebuttal. And finally, PLoS Biology editor Robert Shields offered an overview of the entire controversy.

The discussions are technical. But the conclusions seem to point in one direction: Scientists need a lot more data to figure out how genes cause disease.

Stay tuned for updates over the next decade or so.

Related: More in the Los Angeles Times about direct-to-consumer genetic tests.