A few cases of APL variants with RAR-negative rearrangements have been reported, including myeloid/lymphoid or mixed-lineage leukemia and RNA polymerase II elongation factor ELL (ELL-MLL/MLL-ELL, t(11;19)(q23;p13.3), MLL and AF1Q (MLL-AF1Q, (t(1;11)(q21;q23), MLL and regulation of nuclear pre-MRNA domain containing 2 (RPRD2-MLL, t(1;11)(q21;q23), NPM1 and coiled-coil domain containing 28A (NPM1-CCDC28A, cytogenetic analysis not available), TBC1 domain family member 15, and Ras-associated binding 21 (TBC1D15-RAB21, cytogenetic analysis not available) (77, 92). Here, RAB21 is linked to acute promyelocytic leukemia.