JAK2 and Thrombocytosis: Co-expression of SF3B1 with DNMT3A, TET2 or ASXL1 promotes myelodysplasia with ring sideroblasts, while acquisition of JAK2 mutations, and less frequently MPL (4%) and SH2B3 (4%) mutations, constitute secondary events that promote thrombocytosis and contribute to the myeloproliferative phenotype [4,26,36] (Figure 3C).