BRCA1 and breast cancer: BRCA1 and BRCA2 variants resulting in abrogated function of the encoded proteins confer a high risk of breast and ovarian cancer (Antoniou et al., 2003; Kuchenbaecker et al., 2017), and have been reported to increase risk of several other cancer types (Breast Cancer Linkage C, 1999; Ford, Easton, Bishop, Narod, & Goldgar, 1994; Moran et al., 2012; Thompson, Easton, & Breast Cancer Linkage C, 2002).