Instability of chromosome 7 in colony forming cells of patients with aplastic anemia.

Monosomy 7 in isolated bone marrow mononuclear cells and colony forming cells from patients with aplastic anemia who later developed myelodysplastic syndrome/leukemia with monosomy 7 were examined by fluorescence in situ hybridization. Colonies derived from bone marrow mononuclear cells of the aplastic anemia patients consisted of a mixture of cells of normal karyotype and monosomy 7, ranging from 0 to 97.2%. This result suggests that colony forming cells initially had a normal karyotype but then lost chromosome 7 during growth in the semisolid culture. This finding suggests the genetically unstable condition of chromosome 7 in colony forming cells in aplastic anemia patients. This chromosome instability of colony forming cells may lead to malignant transformation.