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Scientists Take Major Step to Understanding Environment-Genetics Links - 2003-04-19


This month, scientists announced they had determined nearly the entire genetic blueprint for a human being. Cancer, heart disease, asthma, and other diseases are partly genetic, but the environment also plays a role. How genetics and environment interact is one of the most important questions, not only in science, but also in public policy. Researchers have taken a major step toward answering it.

Some people can smoke a pack of cigarettes a day and live to a ripe old age. Others develop lung cancer and die young. Scientists say the difference between these people is partly in their genes.

This week, the Human Genome Project released the most complete record yet of the human species' entire genetic code. But National Institute of Environmental Health Sciences (NIEHS) director Kenneth Olden says that record, or sequence, is just the beginning. "I think it's very clear what the next [step] is. And that is, the focus on gene-environment interaction. It's very clear that we have not solved the riddle of human diseases by elucidating the sequence of the human genome," he says.

Mr. Olden announced that researchers at the NIEHS are one step closer to solving that riddle.

The Environmental Genome Project at the NIEHS has catalogued tiny differences in more than 200 genes that influence how a person's body reacts to the environment.

Mr. Olden says when the institute talks about "environment," it means exposure to chemicals, but also much more. "Lifestyle issues, behavior, diet, nutrition, exposures to pharmaceuticals, all of these are part of the environment," he says.

All these parts of the environment affect different people in different ways. With their new list of gene variations in hand, scientists can now begin to look at what role genetics plays in those differences.

Genes are the blueprints for proteins that do the work in our bodies. Those proteins interact in complex ways, so it is often hard to tell what the effects will be of those little differences in genes, called polymorphisms. NIEHS researcher Les Reinlieb says there are some polymorphisms that by themselves do not seem to mean very much. "In fact, one of them seemed to be something that would improve people's health," he says. "But putting together a bunch of different polymorphisms from a variety of genes, in combination, these sets of polymorphisms actually predisposed individuals to a greater risk of heart failure."

Risk of heart failure, cancer, asthma, and adverse drug reactions are just a few of the areas where genetic variations play a role. Now scientists can start looking at exactly why the same environment affects different people differently.

NIEHS Director Olden says this information will help not just scientists and doctors, but also lawmakers. "I think the kind of data that we're going to generate in the next decade will provide the kind of information that is needed to make rational and sound environmental public policy decisions," he says.

Laws, regulations, and health recommendations usually set a single standard. University of Washington researcher Mary-Claire King says those standards may not be right for everyone. "One size clearly does not fit all. And the difficulty is none of us know yet what size we are," she says.

Sizing up the human population is the Environmental Genome Project's next step.

The project has a long way to go. It currently has a list of more than 300 genes to catalog for variations. And scientists expect that list will grow. And they have plenty of work to do to figure out, for example, how some of these gene variations mean an early death from smoking.

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