Using a GFP-based test system for the analysis of distinct DSB repair pathways, we previously showed that de-repression of error-prone microhomology-mediated end joining (MMEJ) and SSA can be detected in lymphoblastoid cells (LCLs) from individuals with breast cancer predisposing BRCA1, BRCA2 or PALB2 mutations [23–25]. This evidence concerns the gene PALB2 and breast carcinoma.