AML1/ETO Fusion Gene Expression and Clinical Characteristics of Adult Acute Myelogenous Leukemia

Lee, Sung Bae; Kim, Young Il; Yoon, Hwi Joong; Kim, Si Young; Cho, Kyung Sam

Abstract

BACKGROUND: The (8;21) translocation is one of the most frequent karyotypic abnormalities detected in acute myelogenous leukemia (AML). Up to 92% of cases with this translocation are classified as FAB subtype M2. The chromosomal breakpoints involved in t (8;21) have recently been identified to involve the AML1 gene on chromosome 21 and the ETO gene on chromosome 8. The purpose of this study is to find the frequency of the AML1/ETO gene rearrangement in AML-M2 patients with analysis of clinical and hematologic features of the patients according to the presence or absence of the rearrangement.
METHODS
Sixteen patients with AML-M2 were included. RNA were isolated and RT-PCR were done to identify the presence of AML1/ETO rearrangement using Kasumi cell line as positive control. Clinical characteristics were analysed and stastical analysis was done.
RESULTS
AML1/ETO gene rearrangement was positive in 12 (75%) of 16 adult patients with AML-M2. In five patient with t (8;21), the AML1/ETO gene rearrangement were positive. In 11 samples without t (8;21), 7 were positive in the RT-PCR. More tests need to be done to identify the overall incidence of AML1/ETO rearrangement in AML-M2 considering the relatively small number of patients included in this study (n=16). Although there was no significant difference in clinical and hematological findings between the two groups, positivity of Auer rods and incidence of splenomegaly were higher in group with the rearrangement, and two cases with extramedullary tumor formation were noted in the group with the rearrangement while no cases without the rearrangement. AML-M2 patients with AML1/ETO rearrangement had a tendency of higher remission rate to chemotherapy and longer duration of survival than AML patient.
CONCLUSION
Molecular method using RT-PCR to detect AML1/ETO gene rearrangement is very sensitive and rapid. It will be used in diagnosis and more studies on the leukemogenesis and minimal residual disease are needed.