The following day, the results of the bone marrow biopsy showed abnormal neoplastic promyelocytes with occasional Auer rods (Figures 3, 4) and reverse transcriptase-polymerase chain reaction (RT-PCR) testing for t(15;17)(q22;q12) of the PML-RARA fusion gene was positive confirming the diagnosis of APL. This evidence concerns the gene PML and acute promyelocytic leukemia.