U2AF1 and myelodysplastic syndrome: There are only a few genes in MDS that are mutated in high frequency, while many more are found mutated only in a small proportion of patients, with the overall pattern of most frequent mutations comprising SF3B1, TET2, ASXL1, SRSF2, DNMT3A, RUNX1, U2AF1, ZRSR2, STAG2, TP53, EZH2, CBL, JAK2, BCOR, IDH2, NRAS, and NF1 genes (31–34) in order of descending frequency.