ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: In chronic myeloid leukemia (CML) there is a chimeric Breakpoint cluster region protein (BCR)-ABL1 fusion gene present in cells caused by the translocation between chromosomes 22 (BCR) and 9 (ABL1) (9;22; q34;q11) producing a fusion gene, encoding a highly active kinase (Hantschel and Superti-Furga, 2004).