AML1-ETO9a Correlated with C-KIT Overexpression/Mutation and Indicated Poor Disease Outcome in t(8;21) Acute Myeloid Leukemia.

AML1-ETO fusion gene is generated from chromosome translocation t(8;21) in acute myeloid leukemia (AML). It is recently reported that its spliced variant AML1-ETO9a induced leukemia rapidly in murine model. Here we detected AML1-ETO9a expression in 58 of 71 (81.7%) patients with t(8;21) AML by using qualitative RT-PCR. Quantitative RT-PCR revealed significantly higher C-KIT levels in the AML1-ETO9a positive group than in the negative group (P=0.0001). Among 29 cases harbored C-KIT mutations, 28 (96.6%) expressed AML1-ETO9a. Clinically, patients expressing AML1-ETO9a exhibited significantly elevated white blood cell counts and a short overall survival time (P=0.0455 and 0.0039, respectively). Morphologically, although there is no difference of leukemic blasts percentage between AML1-ETO9a positive and negative cases (P=0.1169), the latter possessed more aberrant myelocytes (P=0.0462). Taken together, AML1-ETO9a correlated with C-KIT overexpression/mutation and indicated poor disease outcome in t(8;21) AML.