Mary-Claire King: Fearless Geneticist

A lot of great scientists work steadily in small niches of research for most of their careers. Not geneticist Mary-Claire King; her work spans an impressively wide area of interests: from human evolution, to health, to human rights.

“I can’t resist doing interesting things… basically, you only live once,” King said in an interview with PLoS Genetics. “Otherwise you’ll forever feel terrible that you didn’t go for the ring, for a way of making a major impact on a major area.”

King, currently a professor at the University of Washington, credits her mentor Allan Wilson, the University of California at Berkeley molecular biologist, with her propensity for thinking outside the usual boundaries of scientific disciplines.

“The Wilson laboratory is perhaps best explained as the result of Allan’s loyalty—to his students, to scientific evidence, and to the often maniacal but always rigorous whimsy that comes from shared freedom of thought,” King wrote in a 1991 tribute to Wilson in the American Journal of Human Genetics.

While King was completing her doctorate at the Wilson lab in the 1970s, her work in protein analysis proved that the genomes of humans and chimpanzees are 99 percent identical. This also lent significant credence to her mentor’s theory that humans split off from chimpanzees a mere five million years ago (five million years later than previously thought). In a 1975 paper in Science, King and Wilson hypothesized that genetic regulation—subtle differences in how genes are turned off and on, and how a given gene’s products are made to increase or decrease—is largely responsible for all the differences between humans and our closest primate cousins.

Starting in the mid-1980s, King began using her genetics know-how in the service of human rights work, starting with a campaign in Argentina to reunite children of political dissidents abducted during the “Dirty War” with their surviving family members. The grandmothers of the children, organized as the Abuelas de Plaza de Mayo, had long protested the illegal adoption of hundreds of children by military families. To provide the necessary proof of kinship required for the grandmothers to obtain custody of the children, King devised a new kind of genetic test involving mitochondrial DNA (passed down through the maternal line) and a collection of immune system genes known as human leukocyte antigens. Her methods are still in use today to identify victims of massacres the world over.

But King’s most famous accomplishment is the discovery of the breast cancer gene BRCA-1. Not all scientists were convinced that breast cancer could be heritable in some cases, but King doggedly combed through DNA histories of families for 17 years, rejecting more than 180 possible candidate genetic markers before they zeroed in on a telltale gene on chromosome 17. After BRCA-1 was identified, it also turned out to play a role in other inherited cancers of the breast and ovaries. Now women have the opportunity to see if they carry the BRCA-1 mutation that indicates an elevated risk for these cancers.

King’s achievements are all the more remarkable given that she was working in a climate especially hostile to female scientists.

After King was hired as an assistant professor in Berkeley’s epidemiology department, “the division head said to me, ‘I just want you to know that you are only here because of all these new regulations, and we are really scraping the bottom of the barrel in hiring you,’” she told PLoS Genetics. “And I said, ‘We’ll see how long you feel that way!’”