Clonality analysis of hematopoietic cell lineages in acute myeloid leukemia and translocation (8;21): only myeloid cells are part of the malignant clone

Bone marrow from six patients with acute myeloid leukemia (AML) and t(8;21) (q22;q22) or a variant t(8;13;21) was studied by simultaneous analysis of cell morphology and karyotype. Combination of May-Grünwald-Giemsa (MGG) and fluorescence in situ hybridization (FISH) using probes specific for the breakpoint regions of chromosome 8 and 21 allowed us to establish the extent of cell-lineage involvement of the translocation. The translocation was found in all myeloid blasts and in high percentages of the more mature neutrophilic cells. In one patient we could demonstrate the translocation in the eosinophils as well. Erythroblasts and lymphocytes did not show the t(8;21) abnormality. These results indicate that the t(8;21) in AML is restricted to the myeloid (granulocytic) lineage.