Other pathogenic MPNmutations in calreticulin (CALR) and thrombopoietin receptor (MPL)genes also cause MPN by activating JAK2 signaling.6,7 Inaddition, mutations in JAK2 have been linked to other hematologicmalignancies, such as acute lymphoblastic leukemia, acute myeloidleukemia, and acute megakaryoblastic leukemia.8−10. Here, CALR is linked to myeloproliferative disorder.