BCRP3 and acute promyelocytic leukemia: APL with high WBC is more frequent in children and is often associated with the microgranular variant (M3v), with the short PML-RARα isoform (bcr3), with the FLT3 mutation and the CD56 expression which are all adverse prognostic factors in APL, although not independent from WBC counts.13–18 APL with increased WBC is frequently associated with severe coagulopathy and, sometimes with organomegaly.