And if future studies confirm what Kaati and his fellow researchers suspect? “It might be dangerous to overeat during the slow growth period,” he says. “That’s what is happening now, with kids becoming fatter and fatter.” The resulting harm might conceivably persist for generations to come.

But because these studies are preliminary, researchers are cautious. “There’s almost a wish that epigenetic phenomena affect our lives—that when we change our diet, for example, it might change the way our genes are expressed,” says Adrian Bird, a molecular geneticist at the University of Edinburgh who specializes in methylation. “But we have a way to go before we can be sure.”

Several initiatives may boost this research. The National Institutes of Health names epigenetics one of four “grand challenges in biomedical health/research” that “can be uniquely addressed by NIH as a whole.” Therapies that could turn on important genes, especially for the treatment of cancer, are being developed, and some drugs are believed to modify the epigenome for such diseases as epilepsy and bipolar disorder.

There’s also some concern that industrial chemicals may need to undergo testing to make sure they don’t alter the epigenome in a way that could lead to disease. “In the future, we’ll need to test compounds for their ability not only to mutate our DNA but also to alter the epigenome,” says Duke’s Jirtle.

The field of epigenetics may just be dawning, but it could someday change the way doctors approach medicine. “If you think of the genome as a computer’s hardware, then the epigenome is the software that tells the computer how to work,” says Jirtle. “I think we’ll discover that many diseases aren’t the result of hardware problems—mutations—at all. They’ll turn out to be due to software—epigenetic—problems.”

Dossier

1. “Environmental Epigenomics and Disease Susceptibility,” by Randy L. Jirtle and Michael K. Skinner, Nature Reviews: Genetics, April 2007. A thorough review of the environment’s effects on the epigenome, it uses vivid diagrams and photos to illustrate key points.

2. “Transgenerational Response to Nutrition, Early Life Circumstances and Longevity,” by Gunnar Kaati et al., European Journal of Human Genetics, April 2007. The latest in Kaati’s series of fascinating studies on health in an isolated Swedish village shows that food supply during childhood can alter disease risk generations later.

3. Epigenetics? [http://epigenome.eu] This European site tackles the tough field of epigenetics for the general public with in-depth feature stories, frequent updates from the laboratory and the latest news.

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