Jolie said she shared her experience to bring attention to the issue.
"I chose not to keep my story private because there are many women who do not know that they might be living under the shadow of cancer," she wrote. "It is my hope that they, too, will be able to get tested, and that if they have a high risk they, too, will know that they have strong options."
Women with those gene mutations also need to consider getting their ovaries removed because they also have a high risk for ovarian cancer, a disease that is hard to detect. Some women wait until after they have children and are closer to menopause to do this. Jolie said she started with her breasts because it is a more complex operation. She didn't say if she would eventually have her ovaries removed.
Cheryl Corbin, who had a double mastectomy in the 1990s, said Jolie's experience has the potential to help women around the world.
"As much as I hate that Angelina Jolie had to go through this, I am so happy that someone who is so high-profile, who has such a voice worldwide, can tell her experience firsthand," Corbin said.
Corbin, project manager for the University of Maryland Women's Health clinic, discovered she had a gene mutation after an oncologist suggested she get tested because her mother and grandmother had breast cancer.
She had a hunch the test would return positive. "I just have too much cancer in my family," she said. While she waited for the results, she had decided on a double mastectomy.
"In my own mind, I needed to get rid of my breasts," she said.
Corbin said the double mastectomy was the best decision she could have made. A doctor said there were precancerous cells in her breast tissue and she would have likely developed cancer in a few years.
"I still get choked up thinking about that," she said.
Jolie believes that more women can be saved from a potentially deadly cancer diagnosis.
"Life comes with many challenges," she wrote. "The ones that should not scare us are the ones we can take on and take control of."