A poor prognosis is associated with FTL3 gene mutations in AML and they are found in approximately 5–15% of children and 25–35% of adults with AML.4,7,19,20,23,31 FLT3 mutations are also found in adult and pediatric ALL, but are much rarer than in AML.3,4,9,10 FLT3 is overexpressed at the level of RNA and protein in most B lineage and acute myeloid leukemias. The gene discussed is FLT3; the disease is acute myeloid leukemia.