Mutations in the nucleophosmin-1 (NPM1) gene and the internal tandem duplications (ITDs) of the fms-related tyrosine kinase 3 (FLT3) gene constitute two of the commonest mutations in Acute Myeloid Leukemia (AML), with a significant impact on prognosis. The gene discussed is FLT3; the disease is acute myeloid leukemia.