t(8;21) is a frequent chromosomal translocation in acute myeloid leukemia (AML) and is also reported in lymphoid and biphenotypic acute leukemia.1, 2 t(8;21) fuses the RUNX1 gene (AML1) on chromosome 21 to the ETO gene (RUNX1T1) on chromosome 8, encoding the RUNX1/ETO chimeric transcription factor that represses expression of RUNX1 target genes, promoting self-renewal and blocking myeloid differentiation.3, 4, 5, 6 t(8;21) is insufficient for leukemogenesis and additional co-operating...