While ASXL1 and SRSF2 mutations may reflect age-related clonal hematopoiesis, SETBP1 is more strongly associated with secondary AML, CMML, and aCML—often co-occurring with ASXL1 and SRSF2 in those neoplasms (18, 19). The gene discussed is SRSF2; the disease is atypical chronic myeloid leukemia, BCR-ABL1 negative.