U2AF1 and myelodysplastic syndrome with ring sideroblasts: Mutations in RNA splicing genes, including splicing factor 3b subunit 1 (SF3B1), serine and arginine rich splicing factor 2 (SRSF2), U2 small nuclear RNA auxiliary factor 1 (U2AF1), and zinc finger CCCH-type RNA-binding motif and serine/arginine rich 2 (ZRSR2), are often detected in hematopoietic tumors, such as refractory anemia with ringed sideroblasts (RARS) and chronic myelomonocytic leukemia (CMML), while solid tumors have a lower rate of mutations in these RNA splicing factors, except for SF3B1 in uveal melanoma [2].