CALR and essential thrombocythemia: In a wide range of 298 ET patients treated at Dijon University Hospital, the distribution of various mutations (JAK2V617F, MPL and CALR) and "triple-negative" forms (no mutation detected) was 60%, 16,5%, 4,5% and 19%, which is comparable to previous data reported in the literature (64%, 15%, 4% and 16% respectively) [17].