ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm caused by a translocation of the chromosomes 9 and 22 that results in formation of the Bcr-Abl1 oncogene (1) and a constitutively active c-Abl kinase domain, which drives uncontrolled cell growth and tumorigenesis.