Mutations in spliceosomal genes, in particular splicing factor 3 subunit b1 (SF3b1), were first identified in myelodysplastic syndromes (MDS) [5], myeloproliferative neoplasms (MPN) [6], MDS/MPN [7], and chronic lymphocytic leukemia (CLL) [8], as well as other hematological disorders [9]. The gene discussed is SF3B1; the disease is myeloproliferative disorder.