SEQUENTIAL INTERPHASE FISH ANALYSIS OF M-BCR ABL CHIMERIC GENE-POSITIVE CELLS IN PH-POSITIVE ACUTE MYELOID-LEUKEMIA/

We report a case of Philadelphia (Ph)-positive AML in which interphase fluorescence in situ hybridization (FISH) analysis was performed from diagnosis throughout the course of therapy using major (M-) breakpoin t cluster region (BCR) /minor (m-) BCR and ABL cosmid probes. We also investigated the existence of the M-BCR or m-BCR at the RNA or DNA lev el by the reverse transcriptase polymerase chain reaction and Southern blot analysis, respectively. Complete remission with a normal karyoty pe was achieved after several regimens of chemotherapy and peripheral blood stem cell transplantation (PBSCT), but relapse occurred and his cells became 100% Ph-positive. We detected the m-BCR/ABL fusion gene b y interphase FISH analysis using an m-BCR/ABL translocation probe, and found that FISH analysis was useful for classifying the BCR, identifi ng minimal residual disease, and for predicting imminent relapse after chemotherapy and PBSCT.