RUNX1T1 and acute myeloid leukemia: The most frequently observed karyotypic abnormality in acute myeloid leukemia (AML) is the 8 : 21 translocation resulting in the formation of the RUNX1/ETO oncoprotein that suppresses the expression of PSGL-1 on hematopoietic progenitor cells and deregulates other genes involved in differentiation and proliferation.