Single cell analysis further underscored the substantial clonal diversity in AML: in samples with two different FLT3-ITD alleles, single cells either had wild-type alleles only, or harbored one of the two mutant alleles in a homozygous or a heterozygous state but, interestingly, no single cell was compound heterozygous for the two ITD alleles. Here, FLT3 is linked to acute myeloid leukemia.