ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Oncogenic forms of ABL1, in particular the BCR-ABL1 fusion gene with different breakpoints in BCR gene, are well-recognized for their pathogenic role in leukemias, including chronic myeloid leukemia (CML), some forms of acute myeloid leukemia (AML), and acute lymphoblastic leukemia (ALL).