During further monitoring six patients achieved a deep molecular remission, which we defined as a ≥ 4 log reduction from baseline, with undetectable BCR-ABL1. Only two CML patients (17%) with the e19a2 transcript had high BCR-ABL1 levels and did not reach any IMR level. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.