A mutation already linked to several types of cancer doubles the risk of breast cancer in a woman and multiplies men's slight risk even more dramatically, a new study finds.
The protein encoded by the normal version of the gene called CHEK2 or CHK2 signals a cell to stop dividing if its DNA is damaged, says study coauthor Douglas F. Easton, a genetic epidemiologist at Cambridge University in England.
The protein appears to activate the proteins encoded by cancer-fighting genes BRCA1 and p53, says cancer geneticist Daniel A. Haber of the Massachusetts General Hospital Cancer Center in Charlestown, Mass. The full picture of how these genes and their proteins work is far from clear, he says. Nevertheless, he calls the study "fascinating and unexpected." Haber and his colleagues had earlier implicated a CHEK2 mutation in a syndrome that includes breast cancer, brain cancer, and sarcoma, a cancer of connective tissues.