Rare single PML::RARA fusion transcript from insertion on derivative chromosome 17 in acute promyelocytic leukemia.

Over 90% of patients with acute promyelocytic leukemia (APL) harbor the typical translocation characterized by the dual fusion of PML::RARA and RARA::PML transcripts. Here, we report a case with a single fusion of PML::RARA formed on der(17), without the RARA::PML fusion, and the patient responded well to all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) therapy. To our knowledge, this represents only the fourth reported case of this type. Our findings indicate that the PML::RARA fusion is the primary driver of APL leukemogenesis and the main therapeutic target for ATRA and ATO, suggesting that the RARA::PML transcript may not be essential for APL development.