Examples for suggested driver mutations are the SET-binding protein 1 (SETBP1) in atypical chronic myeloid leukemia (aCML),10,11SRSF2 in chronic myelomonocytic leukemia (CMML),12–14 and CSF3R in chronic neutrophilic leukemia.15,16 Another common diagnostic difficulty that can now be overcome using genetic information is the differentiation between primary myelofibrosis and other causes of bone marrow fibrosis. Here, CSF3R is linked to atypical chronic myeloid leukemia, BCR-ABL1 negative.