The Gene Factor:
Mary-Claire King
Prevention Pioneer

Dr. Mary-Claire King was born in a suburb of Chicago in 1946. As a young woman, she enjoyed reading mysteries and unraveling mathematical puzzles. In high school, she suffered a difficult experience that subtly set her on a path to investigate, and combat, cancer. Her childhood best friend since the age of seven developed a severe illness and was in terrible pain. She died when King was 15 years old. King then learned her friend had been a victim of cancer. "It wasn't a conscious decision," Dr. King remembers, "but I said to myself, 'Something needs to be done.' It's the little pebbles that make a path." Years later, after adding many more pebbles to the path of her life, Dr. King made profound discoveries about the genetic basis of breast cancer.

After high school, she attended Carleton College in Minnesota. There she studied mathematics, graduating early at the age of just 19. From cold Minnesota, she then traveled to sunny California to pursue a PhD in genetics at the University of California, Berkeley. These were turbulent and creative days in Berkeley, at the height of the social movements of the 1960s and the political activism surrounding the Vietnam war. King found it impossible to conduct her scientific research in the tumult seeping across the campus, and she left her studies. She did not leave science, though. She worked for the famous consumer advocate Ralph Nader, conducting scientific studies of the effects of pesticides on farm workers. After a time, King was offered a job with Ralph Nader's organization in Washington, D.C. Considering the offer, she returned to the Berkeley campus to talk about her future prospects as a scientist with her former professor, Allan Wilson. She complained that she never could get her experiments to work in the laboratory and that she was unsure about her ability as a scientist. Wilson saw great potential in King and reminded her of an important lesson: "If everyone whose experiments failed stopped doing science, there wouldn't be any science."

King took Wilson's lesson to heart and returned to her PhD studies, working along side him. Indeed, more than three decades later, King echoes Wilson's advice in her lessons to students about the place of failure in the scientific enterprise: "To do science, you have to not be intimidated by failure, because you're always getting things wrong. Once in a blue moon, everything goes right. Blue moons are rare, but they're very important in science."

For her doctorate, King used the tools of biochemistry and genetics to address an important question in evolutionary theory: How do species evolve? In particular, her mentor Wilson theorized that humans had diverged from chimpanzees five million years ago—much more recently than other scientists thought, scientists who relied upon the fossil record. King and Wilson decided that she should investigate the genetic difference between humans and chimpanzees—that she should bring biochemistry and genetics to bear on this question. Her results were astounding. Genetically speaking, humans and chimpanzees are 99% identical. This genetic similarity gave weight to Wilson's theory of a more recent divergence of humans and chimpanzees than the fossil evidence alone had suggested.

Breast cancer awareness postage stamp.

With this thinking about the genetics that connect the members of a group to one another, and different population groups to each other, King set out to learn more about the epidemiology of cancer—the science of the occurrence of cancer among different groups. Early on, she set herself an ambitious goal. She would try to find genes responsible for breast cancer—a major killer of women. The reach of this goal is truly remarkable, given that most medical scientists of the day believed that breast cancer was caused by a number of different genes interacting with many different environmental factors. Moreover, no one else was then studying breast cancer at the level of DNA.

King took an interesting approach to attaining this goal of finding the breast cancer gene. She went back to her understanding of the genetics of groups to begin her investigation. She found that a distinct group of women, women of Ashkenazi (eastern European) Jewish ethnicity, had tragically high incidences of breast cancer. Clearly, it seemed, these women were inheriting their disposition to develop breast cancer. King undertook to study the genetics of over 1000 of these women to find the gene responsible for causing the breast cancer. In 1990, 15 years after she had begun her search, she had gathered evidence that established that there was a mutation on a single gene in the women she studied. This mutation was responsible for this inherited breast cancer, and the gene where it occured was named BRCA 1. A breakthrough in the understanding of breast cancer, her finding opened up new lines of research for many other scientists to pursue with her.

For Mary-Claire King, science and social action go hand in hand. With her research into the genetics of breast cancer, she also has become a powerful advocate for women's health issues. "I've never believed our way of thinking about science is separate from thinking about life," she says. "Whether we realize it or not, we are all political animals." King pursues the improvement of society through her science, from fighting breast cancer to her more recent efforts to unlock the genetic secrets of HIV-disease and human deafness.

As a young scientist, King spent time teaching and researching in the South American country of Chile. During her time there, Chile was thrown into chaos following a military coup and the assassination of Chilean President Salvador Allende. Some of Dr. King's students, colleagues, and associates were forced to flee the country. Some were killed. Having firsthand experience of the troubles experienced by South Americans in the 1970s, Dr. King took up important work in the 1980s. She has worked to re-unite families in Argentina using the tools of biochemistry and genetics. Families were torn apart in the civil war that gripped Argentina in the middle 1970s. In particular, the military kidnapped and killed many civilians. Among these victims of the military, were several hundred pregnant women. Their children were put into orphanages after they were born, and their mothers were killed. Starting in the middle 1980s, King worked to reunite these children with their grandparents, using genetics to identify them as members of the same family.

Mary-Claire King continues to be a powerful champion for women in the sciences, and for the many causes that she cares about. Among these causes is her passionate interest in the ways that the science of genetics and biochemistry can unlock new understandings of human evolution, and indeed human history. King has recently returned to the study of the genetics of different groups to address profound questions in human history: How are new cultures established and how are they isolated? Who moves across cultures? How do people adapt to new places? Again, Mary-Claire King shows just how strongly science is bound to the human story.

For more information, at other Web sites...

Genomic Views of Human History — see video of Mary-Claire King lecturing on genetics and human history, in multiple formats, from ResearchChannel OnDemand Video, a service of the University of Washington.

Mary-Claire King, Ph.D. — overview of her work, produced for the 16th Annual National MD/PhD Conference at the Given Institute, Aspen, Colorado, July 13-15, 2001.