Translocation t(1;3)(p36;q21) in sideroblastic anaemia.

An unique case of primary acquired sideroblastic anaemia (PASA) with hyperactive thrombopoiesis is described. Chromosome study revealed that the bone marrow cells of the affected patient contained t(1;3)(p36;q21). A prominent feature was marked megakaryocytic hyperplasia with dysmegakaryocytopoiesis. The platelet count temporarily exceeded 500 x 10(9)/1. In addition, we studied the cellular distribution of the unusual chromosome abnormality in this case. Few erythroid colonies (CFU-E and BFU-E) were observed and normal numbers of CFU-GM were formed. Some metaphases containing the clonal karyotypic abnormality were found in the granulocyte-macrophage colonies. However, no abnormal metaphases were apparent in preparations of T and B lymphocytes. The findings in the present case suggest that the long arm of chromosome 3 may contain a region involved in the regulation of megakaryopoiesis. Furthermore, our results strongly indicate that the target cell for chromosomal change is not a pluripotent stem cell (common to lymphoid and myeloid cells) but a progenitor cell common to all myeloid lineages.