IntroductionPhiladelphia-negative myeloproliferative neoplasms (MPN), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are characterized by the presence of mutations involving the Janus Kinase 2 (JAK2), calreticulin (CALR) or myeloproliferative leukemia virus oncogene (MPL) genes (1). Of these, the JAK2 V617F gain-of-function mutation is the most frequently found and is present in >95％ of patients with PV and in about 60％ of those with ET or PMF whereas JAK2 exon 12 mutations are found in the remaining PV patients (2). JAK2 V617F somatic mutations have been detected in granulocytes and platelets and therefore they could potentially be transmitted to recipients of solid organ transplants (3) and in fact the presence of the JAK2 V617F mutation has been detected in otherwise healthy blood donors (4,5).