ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of hematopoietic stem cells, and characterized by overproduction of myeloid cells as well as the presence of the Philadelphia (Ph) chromosome, which leads to formation of the BCR-ABL1 oncogene [1].