AGNOGENIC MYELOID METAPLASIA - CLONAL PROLIFERATION OF HEMATOPOIETIC STEM-CELLS WITH SECONDARY MYELOFIBROSIS

Abstract

The glucose-6-phosphate dehydrogenase (G-6-PD) types and chromosomes of hematopoietic and other tissues were determined in a woman with agnogenic myeloid metaplasia. The patient was heterozygous at the X-linked G-6-PD locus so that both B and A isoenzymes were found in nonhematopoietic cells. In contrast, only 1 G-6-PD type was found in granulocytes, red cells and platelets. She also had a distinctive chromosome abnormality in blood cells but not in other tissues. Agnogenic myeloid metaplasia is apparently a disorder of a pluripotent stem cell and provide strong evidence that it is of clonal origin. In contrast to blood cells, the patient''s cultured marrow fibroblasts had normal chromosomes and both B and A G-6-PD types, suggesting that the marrow fibrosis is a secondary abnormality. At least in this case of agnogenic myeloid metaplasia, the hematopoietic cell proliferation appears to be clonal, and, by inference, possibly neoplastic; the marrow fibrosis is probably not clonal, and therefore appears to be secondary.