The FMS-like tyrosine kinase-3 internal tandem duplication (FLT3-ITD) mutation is a mutation associated with acute myeloid leukemia (AML) in the FLT3 gene. Mutation occurs as internal tandem duplications (ITD) in the FLT3 gene, which is detected by a polymerase chain reaction (PCR) test that amplifies, analyzes DNA fragments, and identifies duplications.  Identification of FLT3-ITD mutations is critical in prognosis assessment, tailoring targeted therapies, and improving outcomes for AML patients.