The findings of a recent study conducted by Falini et al11 on mutations in exon 12 of the nucleophosmin (NPM1/B23) coding gene in chromosomal location 5q35 showed that NPM1 mutations occur in 35.2% of primary AML cases and these mutations are associated with such features as having a high incidence in all morphologic subtypes of AML (the highest frequency was seen in monocytic leukemias), an absence of hematopoietic stem cell markers like CD34 and CD133, a normal karyotype and responsiveness to chemotherapy. This evidence concerns the gene NPM1 and acute myeloid leukemia.