[Ph1-positive leukemia: cytogenetic outline and prognosis]

Ph1-positive leukemias consist of acute leukemia (Ph1 AL) and CML. Cytogenetically, Ph1 AL is often associated with +6, -7, +8, +21, or +Ph1. CML is predominantly accompanied by +Ph1, +8, i (17q), +19 in myeloid crisis and +Ph1, +8, +21 in lymphoid crisis. Thus, i(17q) seems specific for myeloid crisis of CML. Ph1 constricts ABL/BCR within M-BCR in CML and in one half of the adult Ph1 AL. BCR breaks upstream to M-BCR in the other half of adult AL and in most of childhood AL. However, the breakpoint does not affect clinical and hematological features in AL. Consequently, there seems to be two types of Ph1 leukemia; one is AL representing m-BCR rearrangement and the other is CML and Ph1 AL showing M-BCR rearrangement.