There is a very limited number of monogenic HSCT classifiers: only the internal tandem duplications in FLT3 (FLT3-ITD), which occur in ~10–20% of pediatric AML patients, either alone or with WT1 co-mutations, have proven to be of prognostic significance in de novo disease and at relapse [55–57]. The gene discussed is FLT3; the disease is acute myeloid leukemia.