Internal tandem duplications (ITDs) represent the most common type of FLT3 mutation, being most freuquent in patients with normal karyotype (cytogenetically normal AML, CN-AML) and in patients positive for the translocation t(6;9)(p23;q34) or t(15;17)(q22;q21) [1–4]. The gene discussed is FLT3; the disease is acute myeloid leukemia.