Our data show distinct molecular subtypes among high-risk non-BRCA1/BRCA2 tumours based on somatic mutational signatures including (1) tumours with high HRDetect score explained by methylation in BRCA1 or mutations in other HRD-genes, (2) tumours with high mutational burden and low HRDetect score, (3) mutationally quiescent tumours with low HRDetect score, no RS 2 signature but often CDH1 mutations, and (4) mutationally quiet tumours with low HRDetect score but high RS 2 signature and no CDH1 mutations. Here, BRCA2 is linked to neoplasm.