Appeal of ‘genetic puzzles’ leads to National Medal of Science for UW’s Mary-Claire King
In a White House ceremony May 19, President Barack Obama presented the National Medal of Science to Mary-Claire King, University of Washington professor of genome sciences and medicine. The award, the nation’s highest recognition for scientific achievement, honors King’s more than 40 years dedicated to research in evolution and the genetics of human disease, as well as to teaching and outreach endeavors that have supported human rights efforts on six continents and reunited families.
“It’s fantastic,” said King before the ceremony. “It’s a wonderful way to celebrate science and show the next generation that this is a fascinating and worthwhile way to spend one’s life.”
King was among a total of nine recipients this year for the National Medal of Science, which was first awarded by President John F. Kennedy in 1962. Laureates, chosen by a committee from the National Science Foundation, include scientists in the physical, life and behavioral sciences.
A Chicago native, King earned her bachelor’s in mathematics from Carleton College in 1967 and enrolled in graduate school at the University of California, Berkeley. She intended to pursue a doctorate in statistics, but a genetics course prompted her to change fields. At the beginning of each lecture, the professor would write a “genetic puzzle” on the board, a problem that could be solved using the genetic tools and principles they were learning. By the end of class, King and her peers knew which experiments would solve the puzzle. She was hooked.
Switching to the genetics program, King and her doctoral advisor Allan Wilson tackled a new genetic puzzle involving human evolution. Paleontologists and geneticists could not agree on how closely related humans are to our nearest living relatives, the chimpanzees. Wilson and King believed that the solution was to quantify the number of mutations that had occurred in human and chimpanzee genes since they last shared a common ancestor. At the time, gene sequencing was not feasible. So, King undertook a massive project to compare the chemical properties of proteins from human and chimpanzee cells. Based on key differences, King predicted that humans and chimpanzees are an astounding 99 percent identical at the genetic level, and last shared a common ancestor about 5 million to 7 million years ago.
“That time frame and the 99 percent identity have held up over the years, and were finally confirmed by the human and chimpanzee genome sequences,” said King. “It really points to the critical role of regulatory mutations can play in evolution, by affecting when and where a gene is expressed.”
After earning her doctorate in 1972, King took advantage of an exchange program to teach at the University of Chile. She intended to stay in Chile for “quite some time,” but the 1973 coup d’état that toppled the government of Salvador Allende prompted her return to the United States.
Later, as a researcher at the University of California, San Francisco, King used her background in statistics and evolutionary genetics to tackle a new foe — breast cancer. She began to look at breast cancer from the perspective of human genetics.
“The perspective of human genes went against the dominant theory at the time, which was that viruses caused cancer,” said King. “Of course, now we know that viruses cause some cancers, like cervical cancer and liver cancer, and that inherited mutations cause other cancers, like the subset of breast cancer we were studying.”
Even without the ability to sequence genes, King demonstrated evidence that inherited mutations may play a significant role in cancer susceptibility. In conversations with surgeons, she also learned of young patients with aggressive cases of breast cancer that also struck close female relatives.
As she examined the pieces of this puzzle, King suspected that mutations in still-unknown genes may predispose younger women to breast cancer. As a professor at Berkeley, she worked with the National Cancer Institute on a study of breast cancer in more than 4,000 women. She showed mathematically that breast and ovarian cancer in some families followed a specific pattern, most likely caused by mutation of a single gene in each family.
“We predicted that inherited mutations explained between 4 and 10 percent of breast cancer,” said King, “and that women carrying these mutations had a lifetime risk of 80 percent risk of developing breast cancer.”
In 1990, still without modern sequencing technologies, King and her group found the region on human chromosome 17 that harbored the critical gene, which they named BRCA1. Quickly, other colleagues confirmed the location of BRCA1. The painstaking task to identify the sequence of BRCA1 began, and was completed by another group in 1994.
King moved to the UW in 1995 to better collaborate with colleagues in medicine on translating genetics research into clinical use. Today, with affordable and accurate gene sequencing technologies, testing for BRCA1 and BRCA2 mutations is far cheaper.
“A couple of years ago, it cost a woman $4,000 to have only BRCA1 and BRCA2 sequenced,” said King. “Now all 20 known breast cancer genes can be sequenced for this woman for $250.”
King also took on challenges in South America, with global consequences. Beginning in 1984, she developed a new method of genetic testing to reunite grandparents in Argentina with their grandchildren, who were kidnapped as infants in the 1970s by the military regime. King’s efforts and collaborative style in Argentina helped launch the United Nations forensic anthropology team, which continues to use these genetic tests to identify victims of human rights abuses worldwide.
“It’s been a great ride and continues to be,” said King. “UW has been an ideal place for me to bring these ideas together.”
Past UW faculty to receive the National Medal of Science include E. Donnall Thomas in 1990, Hans Dehmelt in 1995 and Richard Karp in 1996. Leroy Hood was an affiliate UW faculty member when he received the medal in 2011. Current UW professor Ernest Davidson received his medal in 2001 while at Indiana University.
King is available through the University of Washington Office of News & Information.