The example of refractory anemia with ring sideroblasts (RARS) is instructive; in three-quarters of RARS, mutations have been recently found in SF3B1, a gene encoding a subunit of a splicing factor (U2 snRNP) and histone acetyltransferase (STAGA) complexes [27,29,31]. This evidence concerns the gene SF3B1 and myelodysplastic syndrome with ring sideroblasts.