STUB1 and chronic neutrophilic leukemia: However, ASXL2 alterations occur much less frequently in other myeloid malignancies, for example t(8;21)-negative de novo and secondary AML (1–3.5%) [51–53], neutrophilic leukemias of ambiguous diagnosis (CNL, aCML, MPN-unclassified, MDS/MPN, and MDS/MPN-U) (3.2%) [36], and CHIP (< 0.5%) [37].