Molecular cytogenetic investigations in a novel complex variant of t(8;21)(q22;q22) with ins(15;21)(q15;q22.2q22.3) in a patient with AML-M2 subtype.

Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous disease characterized by the aberrant proliferation of myeloid stem cells, reduced apoptosis and blockage in cellular differentiation. The present report describes the results of hematological, cytogenetic, and fluorescence in situ hybridization (FISH) analysis in a 25-year-old man diagnosed with AML-M2. Cytogenetic as well as FISH analysis revealed a complex translocation involving four chromosomes, with the karyotype 45,-Y,der(X)t(X;8)(p21;q22),der(8)t(8;21)(q22;q22),ins(15;21)(q15;q22.2q22.3),der(21)t(8;21)(q22;q22). The breakpoints at 8q22 and 21q22 suggested a rearrangement of the RUNX1T1 (alias ETO) and RUNX1 (previously AML1) genes, respectively. Using a dual-color FISH test with RUNX1T1 and RUNX1 probes, we demonstrated an RUNX1/RUNX1T1 fusion signal on the derivative chromosome 8, establishing this translocation as a novel complex variant of t(8;21)(q22;q22).