BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Chronic myeloid leukemia (CML) is driven by the juxtaposition of the Abelson leukemia kinase (ABL) proto-oncogene on chromosome 9 onto the breakpoint cluster region (BCR) gene on chromosome 22 by balanced translocation, creating the signature Philadelphia chromosome (altered chromosome 22) and the BCR::ABL fusion gene [1,2].