The proportion of signature 3 remained associated with BRCA1- and BRCA2-deficiency in the whole-genome sequenced breast cancers from WSI when only exonic mutations were analysed with median proportion of 0.39 and 0.20, respectively, compared to median of 0 in BRCA-proficient breast cancers (P = 3.2 x 10–28 and 3.6 x 10−9, respectively; S1 Fig). The gene discussed is BRCA1; the disease is breast carcinoma.