The AML1/MTG8 Fusion Transcript in t(8;21) Positive AML and its Implication for the Detection of Minimal Residual Disease

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Abstract
The reciprocal translocation t(8;21)(q22;q22) is one of the most frequent chromosomal aberrations in acute myeloblastic leukemia (AML). At the molecular level, this aberration rearranges the gene for the AML1-transcription factor on chromosome 21, which is essential for normal hematopoiesis, to the MTG8 gene on chromosome 8, thereby leading to a specific AML1/MTG8 fusion mRNA. This fusion gene is involved in leukemogenesis presumably by interfering with normal AML1-dependent transcriptional regulation. AML patients with t(8;21) have a favourable response to chemotherapy and a relatively good prognosis after intensive consolidation treatment with high dose AraC or autologous stem cell transplantation. RT-PCR for the specific AML1/MTG8 fusion transcripts can be used for the sensitive detection of residual leukemic cells during and after therapy. However, since a considerable proportion of these patients shows a positive PCR result even in long-term complete hematological remission, the prognostic value of qualitative PCR methods is doubtful. In contrast, quantitative PCR methods might be able to identify patients with a high risk of relapse by serial quantification of minimal residual disease (MRD). Because of its high degree of standardisation and automation, the recently developed real time PCR method can be used for the valid and reproducible detection of MRD in large prospective trials. This technology offers the potential to define the antileukemic efficiency of different treatment elements and the prognostic value of MRD in patients with t(8;21) positive AML.