U2AF1 and myelodysplastic syndrome: Indeed, mutations in splice factors U2AF1, SF3B1, ZRSR2 or SRSF2 were identified in two MDS patients (in both of which treatment failed) and three CMML patients (with treatment failure, complete response and partial response) (Additional file 1: Table S1) and did not correlate with expression of splice variants or 5-AZA treatment outcome, consistent with prior analyses [54–56].