Fms‐like tyrosine kinase 3 (FLT3) is a class III receptor tyrosine kinase (RTK) which plays a role in proliferation and differentiation of B‐cell progenitors, myelomonocytic and dendritic cells, as well as in the maintenance of pluripotent haematopoietic stem cells (reviewed in Toffalini and Demoulin, 2010).1 Activating mutations of FLT3, either in the form of internal tandem duplication (ITD) mutations in the juxtamembrane (JM) domain or point mutations in the tyrosine kinase domain, are frequently reported in acute myeloid leukaemia (AML). The gene discussed is NTRK1; the disease is acute myeloid leukemia.