In contrast to the JAK2 mutations, patients with CALR-mutated PMF were shown to be younger, to have higher platelet counts, were less likely to require blood transfusions for anemia or to present with leukocytosis, and to have a generally more indolent clinical course with better overall survival than JAK2- or MPL-mutated cases [16,17]. Here, JAK2 is linked to anemia (phenotype).