The annual incidence of BCR-/ABL1-negative myeloproliferative neoplasms (MPN), namely polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) in the western world, is estimated to be maximum 2.8, 2.3, and 1.5 cases per 100.000 population, respectively [1, 2]. Here, BCR is linked to acquired polycythemia vera.