Different somatic alterations in Janus Kinase 2 (JAK2), Calreticulin (CALR) and Myeloproliferative Leukemia (MPL) genes, that cause constitutive activation of the JAK2 signal, are considered as ‘drivers’ in MPN pathogenesis.2, 3, 4. Here, CALR is linked to myeloproliferative neoplasm.