Actress Angelina Jolie wrote an honest and informative opinion piece in the New York Times on May 14 revealing that she has undergone a preventative double mastectomy -- an operation that removes all or part of the breast -- because she is a carrier of the breast cancer gene.

"My doctors estimated that I had an 87 percent risk of breast cancer and a 50 percent risk of ovarian cancer, although the risk is different in the case of each woman," she explained. "Once I knew that this was my reality, I decided to be proactive and to minimize the risk as much I could. I made a decision to have a preventative double mastectomy."

Jolie was tested positive for a mutated BRCA1 gene known to greatly increase a woman's risk of breast and ovarian cancers. Her mother, actress and producer Marcheline Bertrand, died in 2007 at the age of 56 after nearly a decade with cancer.

Jolie began the mastectomy process on Feb. 2, with a "nipple delay" procedure to rule out breast cancer behind the nipple. She completed all the mastectomy procedures on April 27, including breast reconstruction with an implant, she wrote.

Health activists and experts have applauded Jolie for her openness in telling her story, and believe that it would help raise crucial awareness of genetic breast cancer risk.

What are the BRCA1 and BRCA2 genes?

BRCA1 and BRCA2 are tumor suppressor genes that usually have the job of controlling cell growth and cell death.

Everyone has two BRCA1 (one on each chromosome #17) and two BRCA2 genes (one on each chromosome #13). When a woman has a harmful or mutated copy of either the BRCA1 or BRCA2 gene, her risk for breast or ovarian cancer is greatly increased.

Genetic tests are available to check for BRCA1 and BRCA2 mutations. A blood sample is required for these tests, and genetic counseling is recommended before and after the tests.

BRCA mutations are rare, say doctors, but for women who are carriers, knowing their status can help them make informed treatment decisions.

Who should consider BRCA testing

The four risk factors that might make testing necessary include having:

1. Having a mother, sister or daughter who had a diagnosis of breast cancer before age 50 or who had cancer in both breasts at any age
2. Ovarian cancer in the family
3. Relatives who have tested positive for BRCA1 or BRCA2
4. Ashkenazi Jewish heritage along with a family history of breast or ovarian cancer