U2AF1 and myelodysplastic syndrome: Early studies by next-generation sequencing revealed a large number of aberrant alternative splicing events in MDS [28], and over 50% of MDS patients have mutations in splicing factors [29], such as serine and arginine domain containing factors, including SRSF2, U2AF1, and ZRSR2, and a U2 snRNP component SF3B1 (in Table 1).