Almost 20% of BC patients share histological features and clinical outcome to BRCA1/2 related cancers without detectable gBRCA1/2 mutations, a phenotype defined as BRCAness. The most common mechanisms that cause BRCAness status are somatic mutations, large deletions, and DNA hypermethylation of BRCA1/2, germline mutations in PALB2, and hypermethylation of RAD51C genes. The gene discussed is BRCA1; the disease is breast cancer.