SF3B1 and myelodysplastic syndrome with ring sideroblasts: SF3B1 is a gene encoding a component of the RNA splicing machinery, and mutations in this gene have been found in MDS patients with RARS; in one study, a mutation in SF3B1 was found in 28% of MDS patients (N = 76), and the proportion of mutation in RARS patients (55%) was higher than that of other MDS categories (9%; p < .001; Ambaglio et al., 2013).