FLT3 overexpression in acute myeloid leukemia (AML) is often caused by mutations in this gene. These mutations cause constitutive phosphorylation of FLT3 proteins leading to increased proliferation and survival, decreased apoptosis and resistance to chemotherapeutic agents in AML cells. There are two major types of FLT3 mutations- internal tandem duplication (ITD) and point mutation at 835th amino residue. AMLs with FLT3 mutations have worse prognosis and are often resistant to conventional chemotherapy. Several small molecule compounds targeting FLT3 have been in the market or in clinical trials. Therefore, identification of these mutations at the time of diagnosis will provide a better prognostic prediction, might guide the treatment selection and follow-up strategies. In this study, the investigators will develop a sensitive molecular assay to detect FLT3 mutations for future clinical application. The investigators will collect 100 AML samples with at least 20 samples with known FLT3 mutations. The investigators will compare this assay with commonly used methods and standardize the procedure to meet the requirement of clinical pathology laboratory with reasonable cost.