SETBP1 and atypical chronic myeloid leukemia, BCR-ABL1 negative: Although the role of SETBP1 in leukemogenesis remains elusive, deleterious mutations of SETBP1 have been reported to occur with high frequency in adults with atypical chronic myeloid leukemia (aCML) [9], chronic myelomonocytic leukemia (CMML) and secondary acute myeloid leukemia (AML) [10–13]; by contrast, mutations have been found only rarely in pediatric myeloid malignancies.