NPM1 and acute myeloid leukemia: These differences are expected because favorable cytogenetic abnormalities are most common in younger patients [1, 6, 58]; AML secondary to previous chemotherapy or chronic myeloid malignancies (i.e. chronic myeloproliferative neoplasia, myelodysplastic syndrome) is most common for elderly patients [5, 62]; and both favorable cytogenetic abnormalities as well as NPM1 mutations are associated with morphological signs of differentiation [58, 63, 64].