BRCA2 and breast cancer: For BRCA2-d, we observed a strong association with the number of deletions at sites of microhomology (Figure 2b), with a median of 608 deletions per patient in BRCA2-d breast cancers versus 81 in BRCA2 WT breast cancers, in agreement with prior findings (Nik-Zainal et al., 2012; Davies et al., 2017; Nguyen et al., 2020).