KMT2A and acute lymphoblastic leukemia: In this respect, assessment of the phylogenetic origin of a rare case of lineage switching from KMT2A rearranged infant B ALL to KMT2A rearranged childhood AML has led these same researchers to suggest that, in this specific case, the KMT2A rearrangement may have occurred before gastrulation and hematopoietic specification [185].