JAK2 and myeloproliferative disorder: The World Health Organization recognizes genetic changes to define specific disease entities such as myeloid neoplasms (MN); myeloproliferative neoplasms (MPN); myelodysplastic/myeloproliferative neoplasms (MDS/MPN); myeloid and lymphoid neoplasms with PDGFRα, PDGFRβ or FGRF1 or PMC1-JAK2 abnormalities (MLN); myelodysplastic syndromes (MDS); and acute myeloid leukemias (AML) (3).