FLT3 and acute promyelocytic leukemia: In APL, two mutations of the fms-related tyrosine kinase 3 gene ( FLT3) are more frequent: the internal tandem duplications ( FLT3-ITD) of the justamembrane region is found in 12-38% of the cases and the missense point mutations involving mainly the D835/I836 residues of the second tyrosine kinase domain ( FLT3-TKD) are observed in 2-20% of the patients [3] .