U2AF1 and myelodysplastic syndrome: Mutations in genes encoding spliceosome components occur in more than 50% of MDS patients, with SF3B1 (Splicing Factor 3b Subunit 1), SRSF2 (Serine and Arginine Rich Splicing Factor 2), U2AF1 (U2 Small Nuclear RNA Auxiliary Factor 1), and ZRSR2 (Zinc Finger CCCH-Type, RNA Binding Motif and Serine/Arginine Rich 2) as the most frequently mutated [129,130].