Molecular cytogenetic findings in a three-way novel variant of t(1;8;21)(p35;q22;q22): a unique relocation of the AML1/ETO fusion gene 1p35 in AML-M2.

Acute myeloid leukemia (AML) is a malignant neoplasm of hematopoietic stem cells characterized by an abnormal proliferation of myeloid precursors, a reduced rate of apoptosis, and an arrest in cellular differentiation. The present report deals with the results of hematologic, immunophenotypic, cytogenetic, fluorescence in situ hybridization (FISH), and molecular analyses of a 53-year-old female patient diagnosed with AML-M2. Cytogenetic and FISH analysis revealed a complex translocation involving three chromosomes showing t(1;8;21)(p35;q22;q22). The observation of breakpoints at 8q22 and 21q22 suggests a rearrangement of the ETO and AML1 genes, respectively. Using a dual-color FISH test with ETO and AML1 probes, an AML1/ETO fusion signal on the derivative 1p35 instead of der(8) was demonstrated. To the best of our knowledge, this is the first report about the relocation of the AML1/ETO fusion gene to the 1p35 rather than der(8), suggesting the presence of a novel variant of t(8;21)(q22;q22) in the observed patient.