Myeloproliferative neoplasms (MPN) include chronic myeloid leukemia (CML), the JAK2/MPL/CALR-associated MPN (essential thrombocythemia, primary myelofibrosis, and polycythemia vera), chronic neutrophilic leukemia (CNL), chronic eosinophilic leukemia, and MPN-NOS/unclassifiable. Here, JAK2 is linked to Chronic Eosinophilic Leukemia, Not Otherwise Specified.