A recent study has shown variable but significantly higher number of MDSCs, defined as CD14−HLA-DR−CD33+CD11b+ cells, in PB of patients with acute myeloid leukemia (AML) compared to patients with acute lymphoblastic leukemia (ALL) and significant correlation of AML-MDSCs with conventional prognostic factors at diagnosis, namely WBC count, CD34 frequency and nucleophosmin (NPM1) and fms-like tyrosine kinase 3 (FLT3) gene mutations. Here, NPM1 is linked to acute lymphoblastic leukemia.