Cytogenetic evidence for a clonal involvement of granulocyte-macrophage and erythroid lineages in a patient with refractory anaemia.

To investigate the clonal origin of refractory anaemia, we carried out cytogenetic studies on single haematopoietic colonies derived from granulocyte-macrophage precursors (CFU-GM) and erythroid precursors (BFU-E). Marrow cells from a patient with refractory anaemia revealed the coexistence of a normal and an abnormal karyotype; 46,XY/45,XY,-15,-18,+der(15q18q). Cytogenetic studies on CFU-GM- and BFU-E-derived colonies obtained from the bone marrow showed the presence of the same karyotypic abnormality carrying the der(15q18q). Colonies carrying a normal diploid karyotype were also detected in the same culture dish. These results indicate that the clone with the der(15q18q) chromosome abnormality arises in a stem cell which can differentiate to at least both granulocyte-macrophage and erythroid lineages.