Genetic heterogeneity in colonies grown from a patient relapsed on quizartinib. (A) Schematic of experimental setup for genotyping of colonies grown from bone marrow of a patient relapsed after a response to quizartinib. (B) Number of colonies after 14 days in methylcellulose in dimethyl sulfoxide (DMSO) and 20 nM quizartinib. Error bars represent standard error of triplicate platings. (C) FLT3 genotype of single colonies plucked from methylcellulose after 14 days of growth in DMSO or 20 nM quizartinib. Each circle represents a particular FLT3 genotype. The relative size of circles is representative of the relative proportion of the overall population with that genotype. Number of colonies with each genotype is shown for DMSO (left) and quizartinib 20 nM (right).