Searching for the 'signature' causes of BRCAness in breast cancer

Breast cancer cells with defects in the DNA damage repair-genes BRCA1 and BRCA2 have a mutational signature known in cancer genomics as 'Signature 3.' But not all breast tumor cells exhibiting Signature 3 have BRCA1 or BRCA2 mutations. Therefore, some consider Signature 3 a biomarker for 'BRCAness,' a sign of a breakdown in BRCA-related DNA repair in general and not BRCA damage in particular.