SH2B3 and essential thrombocythemia: The remaining 10% to 15% of patients with ET or PMF patients have none of the above-mutated genes and these are named “triple negative” (85,90,91). This is a heterogeneous category and some of the ET patients may have rare non-canonical mutations in JAK2, MPL, and SH2B3; however, the large majority remain without a specific mutation.