Genomic structure and nucleotide sequence of AML1-ETO fusion genes in children with acute myeloid leukemia

Background: The human ETO gene at 8q22 is a common fusion partner of the AML1 gene at 21q22, resulting in the translocation t(8;21)(q22;q22). The AML1 gene spans more than 340kb whereas ETO only spans 150kb. Respectively three breakpoint cluster regions (BCRs) have been identified in intron 5 of AML1 and intron 1b of ETO. In infants with AML 11% present a t(8;21) at diagnosis.

Methods: In this study we investigated bone marrow samples from 13 AML-patients with cytogenetically diagnosed t(8;21). Using a multiplex-nested long-range PCR assay, we amplified a breakpoint spanning DNA fragment prior to direct sequence analyses.

Results: The AML1-ETO breakpoints were located within and outside of the published BCRs. Anyhow we have identified a clustering of 5 patient's samples within the breakpoint spanning regions of AML1 and ETO. The other breakpoints could not be assigned to the described BCRs.

Conclusions: We developed a multiplex-nested long-range PCR assay to amplify and sequence t(8;21) breakpoint spanning DNA fragments. Sequence patterns around the breakpoints may provide evidence why certain DNA motifs are favoured for t(8;21).