Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Long-term marrow cultures (LTMCs) provide a selective growth advantage for cytogenetically normal cells in patients with acute and chronic myeloid leukemias. In the present study, LTMCs were established from two patients with newly diagnosed acute myeloid leukemia (AML) who were heterozygous for the X-linked enzyme glucose-6-phosphate dehydrogenase (G6PD). Initially only leukemic clusters grew from cells plated in semisolid medium, but after 1 or more weeks in LTMC, morphologically normal granulocyte-macrophage colonies were detected. Nonetheless, in one of the patients, more than 80% of these colonies expressed the G6PD type observed in the leukemic blast cells, indicating a probable neoplastic derivation for many of them. In the second patient, colonies cultured during the first 3 weeks of the LTMC were predominantly derived from clonal progenitors, whereas after week 4 the colonies were derived from normal stem cells. Colonies derived from clonal or normal stem cells were not morphologically distinguishable. These data support the conclusion that LTMC has a selective anti-leukemic effect on marrow cells from some patients. However, normalization of colony growth is by itself not a sufficient criterion for determination of whether committed progenitor cells from patients with AML are derived from normal or leukemic stem cells.
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PMID:The effect of long-term marrow culture on the origin of colony-forming cells in acute myeloblastic leukemia: studies of two patients heterozygous for glucose-6-phosphate dehydrogenase. 316 89

In previous studies of two patients with polycythemia vera (PV) who were heterozygous at the X-linked locus for glucose-6-phosphate dehydrogenase (G6PD), only A type enzyme was found in nonlymphoid blood cells. However, some erythroid and granulocytic colonies grown in vitro were type B and therefore arose from presumably normal progenitors. One patient had enough type B colonies (8%) that studies of the physical characteristics of normal and PV clonal colony-forming cells could be undertaken. When marrow cells were separated by velocity sedimentation at unit gravity, most PV clonal granulocyte-macrophage progenitors (CFU-C) (type A G6PD) sedimented between 6.4 and 7.2 mm/h, whereas most residual normal, type B CFU-C sedimented less than or equal to 5.9 mm/h (P = 0.04)., When blood cells were separated over a discontinuous buoyant density gradient, PV clonal CFU-C equilibrated at densities < 1.065 g/ml, whereas residual normal CFU-C were found greater than or equal to 1.065 g/ml (P < 0.01). PV clonal and residual normal erythroid burst-forming progenitors were not separable by either method. Thus PV clonal CFU-C are larger and less dense cells than are residual normal CFU-C.
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PMID:Polycythemia vera. Physical separation of normal and neoplastic committed granulocyte-macrophage progenitors. 693 5

Chronic granulomatous disease (CGD) is characterized by recurrent infections, and is usually associated with a complete inability of phagocytic cells to generate superoxide anion (O2-). Rarely, variant forms of CGD have been reported in which there is reduced, but detectable, O2- production by phagocytic cells. We describe three adult males in two kindreds with a unique form of X-linked cytochrome b558-deficient (X91-) CGD not previously reported. All three patients had two distinct populations of phagocytic cells, with one subset capable of normal respiratory burst activity and the other larger subset inactive, as in classic CGD (X91 (0)). The respiratory burst activity in neutrophils purified from each patient was approximately 10% of normal as determined by O2- production, O2 consumption, cytochrome b558 spectroscopy, and membrane oxidase activity using a cell-free activation system. In contrast with other patients with X91(-)-variant CGD, the unique feature of these patients is the presence of a small but significant population (5% to 15%) of circulating neutrophils and monocytes with completely normal respiratory burst activity as assessed by nitroblue tetrazolium (NBT) reduction and flow-cytometric measurement of dihydrorhodamine oxidation. NBT reduction of peripheral blood granulocyte-macrophage progenitor cells also showed the presence of a subset of colonies derived from myeloid progenitor cells that had normal respiratory burst capabilities. A mosaic XX chromosome karyotype and an unstable oxidase complex that might occur during myeloid maturation were both excluded as possible explanations. In these families, the molecular defect in the gp91-phox gene, which is currently under investigation, appears to prevent expression of the gene in the majority of neutrophils, but not in a small subset. Our studies suggest that commitment to either a respiratory burst-competent or -incompetent phagocytic cell occurs at the level of the myeloid progenitor cell.
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PMID:A new X-linked variant of chronic granulomatous disease characterized by the existence of a normal clone of respiratory burst-competent phagocytic cells. 780 97

Mice hemizygous (Xsf/Y) for the X-linked mutation scurfy (sf) develop a severe and rapidly fatal lymphoproliferative disease mediated by CD4+CD8- T lymphocytes. We have undertaken phenotypic and functional studies to more accurately identify the immunologic pathway(s) affected by this important mutation. Flow cytometric analyses of lymphoid cell populations reveal that scurfy syndrome is characterized by changes in several phenotypic parameters, including an increase in Mac-1+ cells and a decrease in B220+ cells, changes that may result from the production of extremely high levels of the cytokine granulocyte-macrophage CSF by scurfy T cells. Scurfy T cells also exhibit strong up-regulation of cell surface Ags indicative of in vivo activation, including CD69, CD25, CD80, and CD86. Both scurfy and normal T cells are responsive to two distinct signals provided by the TCR and by ligation of CD28; scurfy cells, however, are hyperresponsive to TCR ligation and exhibit a decreased requirement for costimulation through CD28 relative to normal controls. This hypersensitivity may result, in part, from increased costimulation through B7-1 and B7-2, whose expression is up-regulated on scurfy T cells. Although the specific defect leading to this hyperactivation has not been identified, we also demonstrate that scurfy T cells are less sensitive than normal controls to inhibitors of tyrosine kinases such as genistein and herbimycin A, and the immunosuppressant cyclosporin A. One interpretation of our data would suggest that the scurfy mutation results in a defect, which interferes with the normal down-regulation of T cell activation.
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PMID:Cellular and molecular characterization of the scurfy mouse mutant. 1007 94

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, immunodeficiency and eczema. X-linked thrombocytopenia (XLT) is a mild form of WAS with isolated thrombocytopenia. Both phenotypes are caused by mutation of the Wiskott-Aldrich syndrome protein (WASP) gene. In this study we investigated the role of WASP in the differentiation of CD34-positive (CD34+) cells isolated from the bone marrow of patients with WAS (n = 5) or with XLT (n = 4). Megakaryocyte colony formation was significantly decreased in patients with WAS when compared with normal controls. The formation of granulocyte-macrophage colonies and erythroid bursts were also decreased in WAS patinets. In contrast, in XLT patients, formation of all these colonies was normal. However, in vitro proplatelet formation of megakaryocytes induced by thrombopoietin was markedly decreased in both XLT and WAS. Electron microscopic examination revealed that megakaryocytes obtained from WAS or XLT patients grown in vitro had abnormal morphologic features, which seemed to be caused by defective actin cytoskeletal organization, including labyrinth-like structures of the demarcation membrane system and deviated distribution of the alpha-granules and demarcation membrane system. These observations indicate that WASP is involved in the proliferation and differentiation of CD34+ haemopoietic progenitor cells probably by its participation in signal transduction and in the regulation of the cytoskeleton.
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PMID:WASP is involved in proliferation and differentiation of human haemopoietic progenitors in vitro. 1058 10

Paroxysmal nocturnal hemoglobinuria (PNH) results from somatic mutations of the X-linked PIG-A (phosphatidylinositol glycan-class A) gene, which occurs on a hematopoietic stem cell level, leading to a proportion of blood cells being deficient in all glycosylphosphatidylinositol (GPI)-anchored surface proteins. Although these GPI-deficient cells can explain many of the clinical symptoms of PNH, the pathogenesis of PNH is still somewhat obscure and many questions remain. To assess the hematopoietic defect involved in PNH, CD34+ CD59+ (normal phenotype hematopoietic stem/progenitor) and CD34+ CD59- (PNH phenotype) cells from PNH patients (n = 16) and CD34+ CD59+ cells from healthy volunteers (n = 10) were sorted as single cells into 96-well flat-bottom culture plates containing culture medium supplemented with stem cell factor, interleukin (IL)-3, erythropoietin, granulocyte-macrophage-colony-stimulating factor (GM-CSF), G-CSF, IL-6, thrombopoietin, and Flt-3 ligand. We found that the single PNH CD34+ CD59- cells had a growth advantage over the single CD34+ CD59+ cells to some extent, but they both had impaired growth abilities compared with CD34+ cells from healthy volunteers.
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PMID:Proliferative capacity of single isolated CD34+ hematopoietic stem/progenitor cells in paroxysmal nocturnal hemoglobinuria. 1153 Aug 4