Combined analysis of the transplantations showed that despite the low number of cells that co-expressed KMT2A-MLLT3 and FLT3N676K at transplantation, these mice displayed accelerated AML onset (median latency 34 versus 50 days for KMT2A-MLLT3 alone, P < 0.0001. Here, MLLT3 is linked to acute myeloid leukemia.