ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: The BCR-ABL transcript is part of the tyrosine kinase class of enzymes, being related to the development of Chronic Myeloid Leukemia (CML) and some forms of severe Acute Lymphoblastic Leukemia (ALL) [1,2,3,4,5,6,7,8,9].