The death of Angelina Jolie's aunt, Debbie Martin, has once again highlighted the genetic risk of breast cancer.

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Martin, 61, was the younger sister of Jolie's mother, Marcheline Bertrand, who died from ovarian cancer at the age of 56. Martin's death comes two weeks after Jolie revealed she'd had a preventive double mastectomy after testing positive for a hereditary mutation in one of the BRCA genes.

Women with mutations in the genes BRCA1 or BRCA2 are five times more likely to be diagnosed with breast cancer and up to 28 times more likely to be diagnosed with ovarian cancer, according to the National Cancer Institute. That means that 60 percent of women with a BRCA mutation will develop breast cancer in their lifetimes, compared with 12 percent of women in the general population, and up to 40 percent of women with a BRCA mutation will develop ovarian cancer, compared with 1.4 percent of women without a mutation.

Angelina Jolie Reveals She Had Double Mastectomy to Prevent Breast Cancer

Less than 1 percent of women carry a faulty BRCA gene, making costly genetic testing unnecessary for most. But women with a mother and aunt diagnosed with breast or ovarian cancer are prime candidates for the test, according to the NCI.

For women who are not of Ashkenazi Jewish descent, the agency recommends genetic testing if you have:

• Two first-degree relatives diagnosed with breast cancer, with one of them before age 51. First-degree relatives include your mother or sister;
• Three or more first- or second-degree relatives diagnosed with breast cancer. Second-degree relatives include your grandmother or aunt;
• A combination of first- and second-degree relatives diagnosed with breast cancer or ovarian cancer;
• A first-degree relative diagnosed with cancer in both breasts;
• A combination of first- or second-degree relatives diagnosed with ovarian cancer;
• A first- or second-degree relative diagnosed with breast and ovarian cancer;
• A male relative diagnosed with breast cancer.

For women of Ashkenazi Jewish descent, who are more likely to carry a specific BRCA2 defect passed from generation to generation, the NCI recommends genetic testing if you have:

• A first-degree relative diagnosed with breast or ovarian cancer;
• Two second-degree relatives on the same side of the family diagnosed with breast or ovarian cancer.

About 2 percent of adult women have a family history pattern described above but, again, less than 1 percent of women will have a BRCA mutation.

"Not every woman in such families carries a harmful BRCA1 or BRCA2 mutation, and not every cancer in such families is linked to a harmful mutation in one of these genes," according to the NCI. "Furthermore, not every woman who has a harmful BRCA1 or BRCA2 mutation will develop breast and/or ovarian cancer."

Women without one of the family history patterns described above are unlikely to have a harmful BRCA mutation, according to the NCI.

Based on her genetic testing results, Jolie opted for a preventive double mastectomy - the surgical removal of both breasts to reduce the risk of breast cancer. Studies suggest that preventive mastectomy can reduce breast cancer risk by about 90 percent in high-risk women, according to the NCI. But surgery carries risks, too, so women are advised to talk to their doctors about the procedure's pros, cons and possible alternatives.

Click here for more information from the National Cancer Institute.