Qualitative and quantitative variations in FLT3 mutations from diagnosis to relapse: majority stable; loss of minor subclones; unbiased relapse distribution of FLT3-ITD⁺ On-ATRA/Off-ATRA; possible On-ATRA relapse bias of FLT3-D835⁺; and coincidence of FLT3-ITD⁺ and PRα/LBD⁺ after relapse On-ATRA. (A) FLT3-ITD mutation-positive cases at diagnosis and/or at relapse. (B) FLT3-D835 mutation-positive cases at diagnosis and/or at relapse. White represents mutation not detected; gray, mutation detected; black, no result available; and darker gray, coincident PRα/LBD mutation. Numbers indicate the percentage of mutant FLT3 allele relative to total FLT3 allele; nonbold indicates minor subclone (< 15%). Four cases each (3 in the same case; 1 each in different cases; supplemental Table 6) were not assayed at diagnosis for FLT3-ITD and/or FLT3-D835 mutations and, additionally, did not have detectable mutations at relapse; thus, these cases are not represented in the figure panels.