BCR and myeloproliferative neoplasm: Chronic myelogenous leukemia (CML) is a clonal myeloproliferative neoplasm derived from pluripotent hematopoietic stem cells (1) and characterized by the presence of Philadelphia chromosome, which is caused by the reciprocal translocation of the ABL1 (Abelson murine leukemia) gene on the long arm of chromosome 9 and the BCR (breakpoint cluster region) gene on the long arm of chromosome 22.