Somatic internal tandem duplication of the gene encoding the fms-like tyrosine kinase receptor-3 (FLT3-ITD) with a high mutant:wild-type allelic ratio (>0.4) or point mutations in the FLT3 activation loop of the tyrosine kinase domain (FLT3-TKD) occur in 15–20% of pediatric AML patients (42). This evidence concerns the gene FLT3 and acute myeloid leukemia.