The NPM1 gene (Nucleophosmin 1) provides instructions for making a protein that plays a role in various cellular processes, including cell division and the regulation of other genes. Mutations in the NPM1 gene, specifically the NPM1 mutation, are associated with certain types of cancers, most notably acute myeloid leukemia (AML).

NPM1 mutation testing is often performed as part of the diagnostic workup for AML, especially in cases with a normal karyotype (no visible chromosomal abnormalities under a microscope). NPM1 mutations are one of the most frequent genetic alterations in this type of leukemia, and detecting an NPM1 mutation helps confirm the diagnosis of AML and aids in classification. NPM1 mutation is also an important factor for predicting prognosis in AML. AML patients with NPM1 mutations, particularly without FLT3-ITD mutations, tend to have a more favorable prognosis. After initial treatment, NPM1 mutation testing can be used to monitor minimal residual disease (MRD), which refers to small amounts of leukemia cells that remain in the body after treatment. Monitoring MRD helps assess the response to therapy and guide further treatment decisions.