BRCA mutation

A BRCA mutation is a mutation in either of the BRCA1 and BRCA2 genes, which are tumor suppressor genes. Hundreds of different types of mutations in these genes have been identified, some of which have been determined to be harmful, while others have no proven impact. Harmful mutations in these genes may produce a hereditary breast-ovarian cancer syndrome in affected persons. Only 5-10% of breast cancer cases in women are attributed to BRCA1 and BRCA2 mutations (with BRCA1 mutations being slightly more common than BRCA2 mutations), but the impact on women with the gene mutation is more profound. Women with harmful mutations in either BRCA1 or BRCA2 have a risk of breast cancer that is about five times the normal risk, and a risk of ovarian cancer that is about ten to thirty times normal. The risk of breast and ovarian cancer is higher for women with a high-risk BRCA1 mutation than with a BRCA2 mutation. Having a high-risk mutation does not guarantee that the woman will develop any type of cancer, or imply that any cancer that appears was actually caused by the mutation, rather than some other factor.

BRCA1

BRCA1 and BRCA1 (/ˌbrækəˈwʌn/) are a human gene and its protein product, respectively. The official symbol (BRCA1, italic for the gene, nonitalic for the protein) and the official name (breast cancer 1) are maintained by the HGNC. Orthologs, styled Brca1 and Brca1, are common in other mammal species.BRCA1 is a human tumor suppressor gene (to be specific, a caretaker gene), found in all humans; its protein, also called by the synonym breast cancer type 1 susceptibility protein, is responsible for repairing DNA.

BRCA1 and BRCA2 are normally expressed in the cells of breast and other tissue, where they help repair damaged DNA, or destroy cells if DNA cannot be repaired. They are involved in the repair of chromosomal damage with an important role in the error-free repair of DNA double-strand breaks. If BRCA1 or BRCA2 itself is damaged by a BRCA mutation, damaged DNA is not repaired properly, and this increases the risk for breast cancer. Thus, although the terms "breast cancer susceptibility gene" and "breast cancer susceptibility protein" (used frequently both in and outside the medical literature) sound as if they describe an oncogene, BRCA1 and BRCA2 are normal; it is their mutation that is abnormal.