title: Pancytopenia as a clonal disorder of a multipotent hematopoietic stem cell.
abstract: Hematopoiesis was investigated in a 14-yr-old girl who had a 2-yr history of stable asymptomatic pancytopenia and who was also heterozygous at the structural locus for glucose-6-phosphate dehydrogenase (G-6-PD). There was no morphologic or cytogenetic evidence for preleukemia and no suggestion of Fanconi anemia. In the skin and sheep erythrocytes-rosetted T lymphocytes, the ratio of G-6-PD A/B activities was 1:1. However, only type B activity was found in peripheral blood erythrocytes, granulocytes, and platelets. Most erythroid bursts and all granulocyte/macrophage colonies formed in methylcellulose culture were derived from the abnormal clone. These findings demonstrate that (a) some cases of pancytopenia are stem cell diseases that apparently develop clonally; (b) circulating differentiated cells originate from this clone; (c) despite a hypoproliferative anemia, the in vivo expression of presumably normal (nonclonal) progenitors is suppressed. In this patient, the relationship between clonal dominance and possible malignancy may be assessed prospectively.
mesh_terms: D001853:Bone Marrow / Q000201:enzymology / Q000473:pathology; D002648:Child; D002999:Clone Cells / Q000201:enzymology / Q000473:pathology; D003114:Colony-Forming Units Assay; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000097:blood* / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000201:enzymology / Q000473:pathology*; D006801:Humans; D007527:Isoenzymes / Q000097:blood* / Q000235:genetics; D010198:Pancytopenia / Q000097:blood* / Q000201:enzymology / Q000235:genetics
chemical_list: D007527:Isoenzymes; D005954:Glucosephosphate Dehydrogenase