Two local sisters know what it means to carry that gene and the difficult decisions that follow.
Shortly after a self exam led to the discovery of the golf ball size tumor in her breast, Julie McKnight had chemotherapy, radiation and then a double mastectomy with reconstruction.
Why the drastic step?
"My mother had breast cancer and has the gene. Her mother has breast cancer -- we don't know if she had the gene or not. My sister has the gene but doesn't have breast cancer, but did have preventative surgery," Julie said.
Julie is a cancer survivor, and she calls her sister a pre-vivor: Someone who takes preventative measures to fight cancer by removing the risk.
It's called the BRCA gene, and it runs in the family, putting their risk of breast cancer at more than 80 percent and ovarian cancer at 50 percent.
Maggie first had a hysterectomy, then a double mastectomy with reconstruction years later.
"Big decision -- huge decision. No one can say it's not," Maggie said.
Angelina Jolie's story made Maggie smile. What was a lonely experience for Maggie is now making headlines and putting the spotlight on a private procedure few women openly talked about.
Doctors stress that there is no single solution for women who carry the genetic mutation, and double mastectomies aren't for everyone.
They also recommend aggressive and regular screenings.
Raw video of the sisters: