Rare variant studies in HBC have generally focused on genes known to be linked to cancer predisposition syndromes such as BRCA1, BRCA2, and the Lynch-syndrome genes (MLH1, MSH2, MSH6, PMS2) among others, which are associated with hereditary breast and ovarian cancer syndrome and predisposition to colon and uterine cancer, respectively. The gene discussed is BRCA1; the disease is Lynch syndrome.