BCR and acquired polycythemia vera: As opposed to AML, BCR::ABL1‐negative myeloproliferative neoplasms (MPNs) are clonal disorders of haematopoietic stem cells (HSCs) with a chronic disease course, that comprise three classical subtypes: polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF).11