SF3B1 and chronic myelomonocytic leukemia: Of these, SF3B1 is by far the most frequently mutated comprising 20–30 % of cases [1,5] and the K700E substitution variant accounts for the majority of SF3B1 pathogenic sequence variants in MDS, refractory anemia with ring sideroblasts, acute myeloid leukemia (AML), chronic myelomonocytic leukemia, breast and pancreatic cancer, as well as, uveal melanoma [3,[6], [7], [8], [9]].