Present in 12–38% of acute promyelocytic leukemia [5,6], FLT3-ITD has been associated with high white blood cell counts (WBCs), the short PML-RARα breakpoint cluster region 3 (bcr3) isoform, and microgranular variant M3 (M3v) APL [6,7,8,9,11]. This evidence concerns the gene FLT3 and acute promyelocytic leukemia.