Clinical outcome stratified according to mutant number and size. (A) Overall survival in patients with up to 4 FLT3/ITD mutants. (B) Overall survival in patients with a single FLT3/ITD grouped in quartiles according to size. Group 1 (smallest) indicates 15 to 27 bp; group 2, 30 to 45 bp; group 3, 48 to 63 bp; and group 4 (largest), 66 to 213 bp, respectively.