BRCA1, or Breast Cancer Gene 1, is a gene located on human chromosome 17. It plays a critical role in the repair of damaged DNA, acting as a tumor suppressor. When functioning properly, BRCA1 helps prevent uncontrolled cell growth that could lead to cancer. Mutations in the BRCA1 gene are associated with a significantly increased risk of breast and ovarian cancer. Women who inherit harmful mutations in this gene have a higher risk of developing these cancers at a younger age compared to the general population. Testing for BRCA1 mutations is a common practice for individuals with a family history of breast or ovarian cancer, as it can inform decisions regarding surveillance and preventive measures.