SF3B1 and myelodysplastic syndrome: Notably, the previous MDS diagnosis of refractory anemia with ring sideroblasts (RARS) required a minimum of 15% ring sideroblasts to confirm a RARS diagnosis [12], while the updated diagnosis of MDS with ring sideroblasts (MDS-RS) requires only 5% ring sideroblasts when accompanied by an SF3B1 mutation (associated with mis-splicing of a mitochondrial iron transporter leading to abnormal accumulation of iron in mitochondria ringing the nucleus) [1].