Alteration of granulocyte-colony stimulating factor 3 receptor (CSF3R) were originally strongly correlated to aCML, however, subsequent studies reported lower incidence of CSF3R mutation (<10%) in aCML, but higher in chronic neutrophilic leukemia (CNL), where it was positive in 80% of cases [20]. Here, CSF3R is linked to atypical chronic myeloid leukemia, BCR-ABL1 negative.