BRCA1 and cancer: In a subtractive copy number analysis, we also observed recurrence-specific deletions of KMT2C and MAD1L1, and frequent mutations across the cohort in KMT2C. Loss of KMT2C (MLL3) is associated with progression and metastatic disease in multiple cancer types, including BRCA1/2 mutated breast and ovarian cancers66–70.