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AUDIE CORNISH, HOST:

From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish.

ROBERT SIEGEL, HOST:

I'm Robert Siegel. And in this part of the program a discovery that changed how we understand cancer. Today it's possible for women to take a simple test to determine if they carry a gene that may increase their risk for breast and ovarian cancer. That was not always the case.

CORNISH: Back in the '70s, when geneticist Mary-Claire King led a small research group at the University of California, Berkeley, she sought to answer this question: Is there an inherited form of breast cancer? Well, 20 years ago this year, King's work lead to the cloning and sequencing of BRCA-1. That's the gene that, when working, suppresses tumors, but mutations in this gene can lead to certain breast and ovarian cancers.

King told me earlier today she was able to identify BRCA-1 because she did not accept the prevailing hypothesis that cancer was caused solely by viruses.

MARIE-CLAIRE KING: The way that I thought about the problem was completely different, not in conflict, but simply complimentary to that idea. That is, that there could be some particular families in which predisposition to cancer could be inherited. What my little group and I were trying to do was to determine whether, for a very common cancer, for breast cancer, there was a subset of the illness that could be explained by this inherited predisposition.

CORNISH: So this idea that there are potentially genetic markers that could be identified, where you could track cancer through a family, what triggered your idea that there would be this genetic link?

KING: For breast cancer we had, time and time again, very good demonstration at the level of statistics and at the level of epidemiology that some families were at high risk of the disease, but without an explanation why that could be true. And in the absence of any other explanation, I was driven to turn to genetics.

CORNISH: What was it like when you landed on an answer, when you had started to kind of pinpoint the location on the chromosome where this gene might be?

KING: So our strategy was to use the idea of mapping a gene, which was, of course, an idea current in genetics at the time. And so the epistomological tool - that is, that we felt we could prove the existence of the gene by showing where it was, and that's what we succeeded in doing. It took 17 years. It took from 1974 until 1990, but by 1990 we had really incontrovertible proof that there was a gene that lived on chromosome 17 in a particular physical locale.

CORNISH: Now, this was all before the Human Genome Project, right? I mean, now we sort of take it for granted that there's this kind of easy mapping technology. If you want to find a gene in a chromosome, just go look it up, spend a couple thousand dollars.

KING: Oh, you could look it up for free. Every listener can, at this moment, look up their favorite gene on the UCSC Genome Browser and it costs nothing and it takes 10 seconds. The Human Genome Project, you're absolutely right, the Human Genome Project had not yet begun when we were working on this project. And the Human Genome Project and our effort to identify BRCA-1 were essentially born at the same time.

CORNISH: Now, in the decades since your work led to this mapping of BRCA-1, there have been many other gene mutations that have been mapped, gene mutations linked to breast cancer. But even though the genetic diagnosis is getting better and easier, has all this data kind of out-paced our understanding of it?

KING: Well, my group actually mapped BRCA-1. The race between 1990 and 1994 was to clone the gene - that is, to actually physically pull it out of the chromosome and understand exactly what it does. The gene was cloned in 1994 and the anniversary this year is of the cloning of the gene. And I think it's adorable that the world is celebrating the anniversary of a gene. I think that's great.

CORNISH: It seems like we're at a point now where we can do all kinds of mapping, you can find out about all these different genes, but that doesn't necessarily make the decision any easier in terms of understanding what kind of treatment you should do or what kind of risk prevention you should take. I mean basically, like, the science has outpaced the treatment.

KING: Well, a challenge that we face as scientists, a challenge that our physician colleagues face is how to understand this very rapidly growing amount of information in a way that we can best empower our patients. What our goal is, is to be able to inform women of genetic information that will lead them to be able to make the best choices for them. And we need to be able to give them data that's complete and that's accurate.

And we need to be able to do that inexpensively and effectively.

CORNISH: Over time, though, do you see that there has been too much emphasis on genes and genetic links and has that been to the detriment of research that could focus on other causes of cancer, like environmental factors?

KING: We now are in a position to understand both what genetic factors are that influence disease and what the limitations of those factors are, so that with information we have power. With information we're now in a position to say genetics only goes this far. Beyond this we need to think about environmental causes. And in fact now, the understanding of environmental causes of disease and the understanding of genetic causes of disease are moving hand in hand rather than in conflict.

CORNISH: I wanted to ask you one thing personally. You've said in the past that as a woman doing this work there was a certain freedom in your research when you were starting out in the '70s, freedom in being ignored. In what way?

KING: As a young scientist, it can be liberating to not have expectations placed on you. If you can work quietly, if you can obtain funds for your work - and I could obtain modest funds for my work and I could work in a way that allowed me the time and the space to develop evidence until I was convinced of it, and that's, of course, the highest bar, is to convince yourself that your evidence is good.

Then once you are convinced of your evidence and then you present it, then of course you're no longer being ignored. Then you're being attacked from all sides and you need to be able to defend your evidence. But if you've had 17 years to do it, to build it, you're in a much better position to be able to defend it well.

CORNISH: But it was interesting because I remember you saying that you were a child of affirmative action, and at that time did it really feel like - not just that people were ignoring you, but that they were dismissive of your work?

KING: When one is a child of affirmative action, one needs to anticipate that people, particularly those who have not benefitted from affirmative action, will not take you seriously for a while. But there's a wonderful phrase from Simone de Beauvoir and she says for a woman to be taken as seriously as a man, she must be three times as effective. Happily, this is not difficult.

CORNISH: Marie-Claire King, she's a geneticist and professor of genome sciences and of medicine at the University of Washington in Seattle. Thanks so much for your time.

KING: My pleasure, Thank you.

CORNISH: Marie-Claire King writes about the race to clone BRCA-1 in this month's Science magazine.

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