BCR and chronic myelogenous leukemia, BCR-ABL1 positive: In our systematic review, the majority of BCR::ABL1/JAK2 V617F double-positive cases fell into the group of Ph-negative MPN preceding CML (49.42%), followed by the group of CML and Ph-negative MPN occurring simultaneously (27.58%) and by the group of CML preceding Ph-negative MPN (22.98%).