These common variants at 10 locations across the genome represent perhaps dozens of yet-to-be-identified genes that affect this trait, Chakravarti adds. Of the 10, one that had been previously identified Nos1ap was confirmed. Several others were suspected culprits, the effects of which hadn't been demonstrated in preliminary screens.
"However, almost half were surprising new genes that no one would have guessed as being involved in cardiac biology," says Dan Arking, Ph.D., an assistant professor in the McKusick-Nathans Institute of Genetic Medicine. "So it really does open up a new world of investigation because these are genes that would have never come up if we had only focused on a list of known candidate genes."
A separate study, led by Christopher Newton-Cheh, M.D., M.P.H., of the Massachusetts General Hospital Center for Human Genetic Research and Cardiovascular Research Center , found similar results from more than 13,000 individuals. "We were very reassured to see such strong replication in two independent studies," says Newton-Cheh.
While any single genetic variation in any one individual does not necessarily imply a significant alteration to QT interval, much less increased risk of sudden cardiac death, there is meaning that resides in the collective.
The power of this genetic analysis is a result of screening many thousands of samples, says Chakravarti: "We're not very good at predicting what happens to any one, single sample. It's sort of like, I could examine in great detail how important my vote was in the last election, but it's trivial compared to the collective vote. An individual's genome is important as part of the study's whole, but individually, it's of little consequence."
Likewise, if scientists analyze the effect on
|Contact: Maryalice Yakutchik|
Johns Hopkins Medical Institutions