BCR and acquired polycythemia vera: The World Health Organization (WHO) categorizes MPNs into two groups: Ph+MPN, typically referred to as chronic myeloid leukemia (CML) due to the presence of the BCR/ABL1 fusion gene, and Ph−MPNs, encompassing conditions such as essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) [1, 2].