CUX1 and chronic myelomonocytic leukemia: CUX1 mutations are more common in myelomonocytic diseases such as chronic myelomonocytic leukemia (CMML; an MDS/MPN characterized by monocytosis and hematopoietic dysplasia)18,20 and high-risk MDS19, with biallelic CUX1 mutations being infrequent, consistent with CUX1 being predominantly a haploinsufficient tumor suppressor18,21.