The present study analyzes the demographic, laboratory, and clinical features of the CALR mutation and its prognostic impact.<h4>Materials and methods</h4>The clinical impact of CALR mutations was assessed in 391 ET patients.<h4>Results</h4>CALR-mutation patients were more commonly male than JAK2 V617F-positive and triple-negative patients. This evidence concerns the gene CALR and essential thrombocythemia.