U2AF1 and myelodysplastic syndrome: MDS is a clonal hematopoietic stem cell abnormality disorder related to genetic defects, including epigenetic pathways (DNMT3A, TET2, IDH1/2, ASXL1, EZH2, UTX), RNA splicing machinery (SF3B1, U2AF1, SRSF2, ZRSR2, PRPF8), signaling pathways (JAK2, CBL), transcription factors and corepressors (RUNX1, TP53, BCOR/BCORL1), RAS family pathways, the cohesion family, and other less frequent molecular mutations, such as SETBP1, as well as nonmolecular mechanisms, including bone marrow microenvironment factors, apoptosis, cytokines, immunoregulation, the T-cell repertoire and telomere length20.