Mutations in U2AF1 are present in patients with MDS (in approximately 11% of cases), myeloproliferative neoplasms (MPN), clonal hematopoiesis of indeterminate potential (CHIP), acute myeloid leukemia (AML, in about 4% of patients), chronic lymphocytic leukemia (CLL), and a variety of solid tumors [1]. The gene discussed is U2AF1; the disease is myeloproliferative neoplasm.