Fergus J. Couch, Ph.D., chair of Experimental Pathology and Laboratory Medicine at Mayo Clinic's campus in Rochester, Minnesota, discusses Prediction of breast cancer risk based on profiling with common genetic variants, a study that shows that combining 77 common genetic variants into a single risk factor can be used to improve the identification of women with an elevated risk of breast cancer. This factor, known as a polygenic risk score, was built from the genetic data of more than 67,000 women.