What's BRCA1?

Angelina Jolie’s announcement today about her double mastectomy is a shocking one. In a piece she wrote for the New York Times, “My Medical Choice,”  she tells the ordeal she went through, discovering that she inherited the gene BRCA1, which gave her an 87 percent risk of developing breast cancer, and a 50 percent chance for ovarian cancer. Here’s what you should know about the gene.