Is breast cancer sometimes hereditary?!

Is breast cancer sometimes hereditary?

Family history of breast cancer -- You may also have a higher risk for breast cancer if you have a close relative has had breast, uterine, ovarian, or colon cancer. About 20-30% of women with breast cancer have a family history of the disease.(MedlinePlus)
In 5% of breast cancer cases, there is a strong inherited familial risk. Two autosomal dominant genes, BRCA1 and BRCA2, account for most of the cases of familial breast cancer. Family members who harbor mutations in these genes have a 60% to 80% risk of developing breast cancer in their lifetimes. Other associated malignancies include ovarian cancer and pancreatic cancer. If a mother or a sister was diagnosed breast cancer, the risk of a hereditary ‘’’BRCA1’’’ or ‘’’BRCA2’’’ gene mutation is about 2-fold higher than those women without a familial history. In addition to the BRCA genes associated with breast cancer, the presence of NBR2, near breast cancer gene 1, has been discovered, and research into its contribution to breast cancer pathogenesis is ongoing. Commercial testing for ‘’’BRCA1’’’ and ‘’’BRCA2’’’ gene mutations has been available since at least 2004. Genetic testing for BRCA gene mutations is conducted exclusively by Myriad Genetics, located in Salt Lake City. (Wikipedia)
In most cases, it isn't clear what causes normal breast cells to become cancerous. Doctors do know that only 5 percent to 10 percent of breast cancers are inherited. Families that do have genetic defects in one of two genes, breast cancer gene 1 (BRCA1) or breast cancer gene 2 (BRCA2), have a much greater risk of developing both breast and ovarian cancer. Other inherited mutations — including the ataxia-telangiectasia mutation gene, the cell-cycle checkpoint kinase 2 (CHEK-2) gene and the p53 tumor suppressor gene — also make it more likely that you'll develop breast cancer. If one of these genes is present in your family, you have a 50 percent chance of having the gene. (MayoClinic)
Family history of breast cancer in a 1st-degree relative (mother, sister, daughter) doubles or triples risk of developing the cancer, but history in more distant relatives increases risk only slightly. When ≥ 2 1st-degree relatives have breast cancer, risk may be 5 to 6 times higher. About 5% of women with breast cancer carry a mutation in one of the 2 known breast cancer genes, BRCA1 or BRCA2. If relatives of such a woman also carry the gene, they have a 50 to 85% lifetime risk of developing breast cancer. Women with BRCA1 mutations also have a 20 to 40% lifetime risk of developing ovarian cancer; risk among women with BRCA2 mutations is increased less. Women without a family history of breast cancer in at least 2 1st-degree relatives are unlikely to carry this gene and thus do not require screening for BRCA1 and BRCA2 mutations. Men who carry a BRCA2 mutation also have an increased risk of developing breast cancer. The genes are more common among Ashkenazi Jews.(Merck)
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