The clinical course of CALR-mutated ET patients was reported to be better than in the presence of the JAK2V617F mutation, as subjects with CALR mutations seem to suffer from a lower risk of thrombosis when compared with both JAK2- and MPL-mutated cases, with a favorable impact on thrombosis-free survival (TFS) (19–23). The gene discussed is MPL; the disease is essential thrombocythemia.