NPM Mutations in Adult AML with Normal Karyotype: A Retrospective Study of the Acute Leukemia French Association (ALFA)

NPM mutation (NPMm) has been recently reported as the most frequent mutation in AML, especially in the presence of a normal karyotype. Association of NPMm with an increased complete remission (CR) rate has been suggested, but the long-term prognosis is not known. The abnormal mutated NPM protein shows an aberrant cytoplasmic localization that allows an immunohistochemical detection of NPM status. However, all mutations reported are insertion/deletion of exon 12 resulting in a global insertion of 4 nucleotides. We therefore developed a NPMm detection test based on DNA PCR amplification and fragment length analysis. As previously reported, we observed a higher frequency of NPMm in AML with normal karyotype (47%, 50/106) than in CBF AML (0%, 0/7) or in AML with poor risk cytogenetic (13%, 4/32). We further evaluated the clinical profile and the prognosis of NPM mutations in a retrospective cohort of 106 patients with normal karyotype treated according to the ALFA-9000 or ALFA-9802 protocols between 1990 and 2004. In these patients aged 17–65 years, NPMm was significantly associated with a high white blood cell count (69 vs 18 G/L, p