U2AF1 and myelodysplastic syndrome: Mutations in U2AF1 and SRSF2 affect the spliceosome and are frequently found in antecedent hematological disorders, such as myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPN), as well as are mutations in chromatin regulating genes ASXL1 and BCOR.