Similar finding has been reported in murine model that marked thrombocytosis was rapidly induced in CALR-del52-expressing mice and then progressed to myelofibrosis, and CALR-ins5-expressing mice only developed modest thrombocytosis resembling mild ET phenotype.12 This is consistent with the clinical finding that CALR-del52 mutation is more frequently detected in PMF than in ET,5 and also confirms the differential effects of CALR variants on thrombopoiesis and clinical phenotypes.10, 38, 39. The gene discussed is CALR; the disease is essential thrombocythemia.