Detection of leukemia-related karyotypes in granulocyte/macrophage colonies from a patient with acute myelomonocytic leukemia.

We performed cytogenetic analysis of 11 normal-appearing granulocyte/macrophage colonies derived from cultures of the marrow of a child with acute myelomonocytic leukemia in relapse. We found diploid karyotypes and two abnormal ones--both hyperdiploid and containing the translocation t(1q-;11q+). A clonal origin of the karyotypic differences was suggested by the absence of variation within individual colonies. The evidence suggests that in this patient, the cytogenetic abnormality originated at or before the stage of granulocyte/macrophage progenitor.