In the large group of cytogenetically normal AML (CN-AML, 40–50% of all AML cases), which show no chromosomal aberrations in conventional banding analysis, currently the identification of novel gene mutations allows dissection of CN-AML into prognostic subgroups [4], and mutations affecting CEBPA and NPM1 are considered as provisional AML entities in the WHO classification [5]. Here, NPM1 is linked to acute myeloid leukemia.