As reported in several studies, WBC counts and parallel bone marrow/peripheral blood (BM/PB) blast percentages are higher in inv(16) than t(8;21) AML, at diagnosis [6,7,8,40], proposing a somewhat different type of proliferation kinetics, perhaps related to additional genetic aberrations, such as receptor tyrosine kinase (RTK) mutations [19]. This evidence concerns the gene NTRK1 and acute myeloid leukemia.