FLT3 and acute myeloid leukemia: NPM1-A(+) patients in our study were characterized by higher leukocyte counts at diagnosis, higher frequency of normal karyotypes, higher frequency of FLT3-ITD, and lower incidence of CD34(+) immunophenotypes, supporting the idea that the specific features of type A mutations of the gene might contribute to the general clinical and laboratory profiles of AML patients with NPM1 mutations.