Identification of ins(8;21) with AML1/ETO fusion in acute myelogenous leukemia M2 by molecular cytogenetics

A high percentage of cases of acute myelogenous leukemia (AML) of the M2 subtype show a rearrangement between the AML1 and ETO genes. The detection of the AML1/ETO fusion has clinical relevance because patients with this subtype have a good prognosis. We present the results of conventional and molecular cytogenetic studies in a patient with acute myelogenous leukemia French–American–British M2 classification, who had a complex karyotype involving chromosomes 8 and 21. Dual-color fluorescence in situ hybridization (FISH) using the AML1/ETO probe demonstrated a recombination of both genes on an add(8) chromosome. The use of other FISH probes (CEP8, c-myc and TEL21) and spectral karyotyping indicated that AML1/ETO fusion occurred as a consequence of a previously undescribed ins(8;21)(q22;q22.1q22.3).