t(8;21) AML-ETO

The AML1-ETO rearrangement t(8;21)(q22;q22) has been reported in acute myeloid leukemia (AML) subtype M2. Synonyms for AML1 (acute myeloid leukemia 1 gene) are PEBP2a (polyoma enhancer binding protein 2 subunit a) or CBFA2 (core binding factor subunit A2) and for ETO (eight twenty one) CDR (cyclin D-related gene) or MTG8 (myeloid translocation gene on chromosome 8).

The breakpoints of AML1 are located between exon 5 and 6 and upstream of exon 2 regarding ETO. The in-frame fusion of AML1 exon 5 to ETO exon 2 can be detected by RT-PCR. Both TaqMan and LightCycler® hybridization probes1,2 based Real-Time PCR methods have been published.

The persistence of t(8;21) makes a quantification detection of fusion gene expression more necessary than a qualitative result with reference to a risk-adapted therapy or a MRD (minimal residual disease) monitoring. The quantification is normalized against a reference gene. In addition of the frequently used glucose-6-phophate dehydrogenase G6PDH 3 (LightMix® Kit 40-0137-16) the Abl1 gene has been recently introduced, following the recommendation of the EU consortium4.

1 Quantitative detection of AML1-ETO rearrangement by real-time RT-PCR using fluorescently labeled probes. Barragan E, Bolufer P, Moreno I, Martin G, Nomdedeu J, Brunet S, Fernandez P, Rivas C, Sanz MA. Leuk Lymph. 42 (2001) 747-756

2 New score predicting for prognosis in PML-RARA+, AML1-ETO+, or CBFBMYH11+ acute myeloid leukemia based on quantification of fusion transcripts . Schnittger et al., Blood (2003)

3 Accurate and rapid analysis of residual disease in patients with CML using specific fluorescent hybridization probes for real time quantitative RT-PCR. Emig M. et al., Leukemia (1999) 13, 1825-1832

4 Evaluation of candidate control genes for diagnosis and residual disease detection in leukemic patients using ‘real-time’ quantitative reverse-transcriptase polymerase chain reaction (RQ-PCR) – a Europe against cancer program. Beillard et al. Leukemia. 2003 Dec;17(12):2474-86

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