With a fine characterization of the breakpoints mapping, we narrowed the BPs regions involved in the t(9;22) in CML, and we assessed a high presence of LINE1 elements belonging to the L1M subfamily: 10 different L1M elements in the ABL1 cluster region (L1MCc, L1MEc, L1ME1, L1MEf, L1Med, L1MC5, L1ME4a, L1MB4, L1M5, and L1MC4) and two L1M elements in the M-bcr cluster region (L1MC1 and L1ME). This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.