HRD can result from germline (as observed in hereditary cancers) or somatic mutations of a multitude of genes, BRCA1 and BRCA2 being the most well-known, due to the increased likelihood of developing breast (56–65% for BRCA1, 35–57% for BRCA2) or ovarian (20–50% for BRCA1, 5–23% for BRCA2) cancers, but also pancreatic, prostate, or colorectal cancers, and with an increased likelihood of synchronous cancers [175,176,177,178]. The gene discussed is BRCA1; the disease is colorectal cancer.