Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002874 (aplastic anemia)
 5,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Investigation of a family with cancer in boys revealed that at least 20 males had the X-linked recessive lymphoproliferative syndrome. A variety of phenotypes occurred: aproliferative phenotypes consisted of aplastic anemia, agranulocytosis or acquired hypogammaglobulinemia; and proliferative phenotypes of B cells included disorders associated with the Epstein-Barr virus, American Burkitt's lymphoma, immunoblastic sarcoma of B cells, fatal infectious mononucleosis or plasmacytoma. The lymphoproliferative disorders observed in males could have resulted from an immunodeficiency to Epstein-Barr virus. The variable phenotypic expression could have resulted from individual differences in the viral dose, duration of exposure and age at which the boys were exposed to the virus. Aproliferative phenotypes such as acquired hypogammaglobulinemia could have ensued from excessive suppressor-cell activity on B cells, whereas proliferative phenotypes such as Burkitt's lymphoma or fatal infectious mononucleosis could have resulted from infection by Epstein-Barr virus and failure to stop proliferation of B cells.
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PMID:Variable phenotypic expression of an X-linked recessive lymphoproliferative syndrome. 19 60

Dyskeratosis congenita (DC) is a rare form of ectodermal dysplasia consisting of dystrophic nails, hyperpigmentation, and leukoplakia often associated with aplastic anemia. DC is considered to be an X-linked recessive trait, but affected females suggest genetic heterogeneity. We report an additional female with DC and review the world literature, indicating transmission in X-linked recessive, autosomal recessive, and autosomal dominant manners. The clinical and genetic aspects of DC are heterogeneous, and different patterns of inheritance are associated with distinct clinical manifestations. DC should be considered in the diagnosis of a patient with any features of the syndrome regardless of gender. Conversely, DC should be considered in patients with aplastic anemia at any age.
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PMID:Dyskeratosis congenita: clinical and genetic heterogeneity. Report of a new case and review of the literature. 145 94

The X-linked lymphoproliferative syndrome (XLP), also known as Duncan's disease, is an X-linked recessive disorder that is characterized by the inability of affected individuals to mount a sufficient immune response to Epstein-Barr virus (EBV). After EBV primary infection, male family members suffer from severe infectious mononucleosis (IM), aplastic anemia, hypogammaglobulinemia, and a spectrum of lymphoproliferative diseases. Autosomal mode of inheritance with similar symptoms as in XLP has been reported. We have studied two families with EBV-associated syndromes and an X-linked and an autosomal mode of inheritance, respectively. Affected family members presented with severe IM, hemophagocytosis, aplastic anemia, acquired hypogammaglobulinemia, and B-cell lymphoproliferative diseases.
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PMID:Epstein-Barr virus-associated lymphoproliferative syndromes: studies in two European families. 164 73

Two brothers in a Chinese family were affected with dyskeratosis congenita (DC). The proband's stepbrother died of pancytopenia and rectal adenocarcinoma. The proband with progressive pancytopenia was studied in genetics and hematology. Family investigations suggest that the disorder was inherited as an X-linked recessive transmission. No specific chromosome aberrations were detected in both peripheral blood and bone marrow cells. Bone marrow biopsy revealed markedly hypocellular marrow without prominent reticulin fibers. Hematopoiesis was assessed by assay of granulomonocytic (CFU-GM) colonies and clusters in vitro. Numbers of CFU-GM were profoundly reduced in marrow cultures from our patient. Although a defect in the stromal microenvironment and lymphocyte mediated suppression could not be excluded. It is possible that the defect is intrinsic to the hematopoietic stem cells. The familial disease described by this paper favors that the dyskeratosis congenita is X-linked with constitutional aplastic anemia. It is believed that the pancytopenia with hypocellular marrow in DC is an inherited rather than an acquired condition.
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PMID:[X-linked dyskeratosis congenita with aplastic anemia--genetic and hematologic studies]. 247 34

Dyskeratosis congenita (DC), or the Zinsser-Engman-Cole syndrome, is a rare X-linked heritable disorder, affecting primarily the ectodermal tissues, with hyperpigmentation of the skin, leukoplakia of the buccal and anal mucosa, and nail dystrophy (1, 2). Aplastic anemia (3) and a variety of neoplasms (4, 5) are some of the extraectodermal manifestation of this disorder, which although X-linked recessive, has also been described in a few females (6, 7). Mental retardation, diarrhea, and gastrointestinal bleeding have been considered to be less frequent features (8). We report an adolescent Indian male who presented with all the ectodermal manifestations, as well as mental retardation, bone marrow aplasia, and gastrointestinal hemorrhage secondary to adenocarcinoma of the stomach.
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PMID:Case report: gastric carcinoma as a complication of dyskeratosis congenita in an adolescent boy. 901 39

Dyskeratosis congenita (DC) is a rare hereditary disorder of skin which may be associated with aplastic anemia. The pattern of inheritance is X-linked recessive in most instances, but autosomal dominant and autosomal recessive types have been documented. Reticulated hyperpigmentation usually is the first manifestation. The pigmentary changes may be limited to neck, upper chest, and proximal parts of the limbs initially but within affected areas the involvement is always diffuse. We report on a patient with typical diffuse cutaneous signs of dyskeratosis congenita superimposed with hyperpigmentation that was more pronounced along Blaschko's lines. To explain this phenomenon, we assume that the patient has the autosomal dominant type and that loss of heterozygosity occurred in a somatic cell giving rise to a population of cells that migrated along these lines during embryogenesis.
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PMID:Dyskeratosis congenita with linear areas of severe cutaneous involvement. 948 92

There are several common themes that are emerging from our expanding knowledge about the inherited bone marrow failure syndromes. Patients have a spectrum of birth defects, which are relatively characteristic for each syndrome. but overlap in features such as poor growth. radial ray anomalies, and involvement of skin, eyes, renal, cardiac, skeletal, and other organs. Within each syndrome the composition and severity of the physical phenotype varies widely, and it may require the astute observer to make the correct diagnoses in the milder cases. There is also a wide spectrum to the hematologic picture. These range from single cytopenias such as DBA, SCN, and TAR, which do not develop pancytopenia, to SD and Amega patients who begin with deficiency of a specific single lineage, but evolve to aplastic anemia, to patients with FA or DC, who may present with a deficiency of any one of the cell lines, but almost inevitably end up with full-blown aplastic anemia. Acute myeloid leukemia has been observed in FA, DBA, DC, SD, SCN, and Amega, although not yet in TAR patients. MDS has also been reported in all of the same disorders as AML, although whether it is a preleukemic condition or an independent bone marrow dyspoiesis is not yet clear. Solid tumors are also now appearing in patients whose underlying disease involves hematopoiesis and physical development. These tumors occur at much younger ages than in the general population, in patients who do not appear to have the usual risk factors, and have patterns that are characteristic to the syndrome, such as head and neck and gynecologic cancers in FA and DC, and osteogenic sarcomas in DBA. The other syndromes have not yet been reported to have a propensity for solid tumors. Several genes have been identified that are mutant in some of the syndromes, although the pathophysiology is still not entirely clear. The inheritance patterns include X-linked recessive, autosomal dominant, autosomal recessive, and even mitochondrial. The FA gene products appear to cooperate, and are important in the pathways involved in response to DNA damage. However, the role of this pathway in developmental defects, hematopoietic failure, and the specific malignancies in FA is not fully elucidated. The DC gene products are important for maintenance of telomere length, which may have relevance to development of aplastic anemia and malignancies, but the relation to the physical phenotype is less apparent. The role of mutations in c-mpl in Amega is more straightforward. since the gene codes for the receptor for thrombopoietin. which is the hormone required for megakaryocyte and platelet development; patients with mutant c-mpl do not have birth defects. The role of mutations in RPS19 in erythropoiesis or developmental defects in DBA patients is not obvious, and the increased frequency of osteogenic sarcomas suggests that at least that subset of patients may have a mutant tumor suppressor gene (such as p53, the mutant gene in Li-Fraumeni syndrome) [68]. Although patients with SCN have mutations in neutrophil elastase, patients with similar mutations may have relatively benign cyclic neutropenia, or may even have normal neutrophil levels [69,70]. The mitochondrial gene deletions in Pearson's Syndrome result in variable degrees of acidosis, and varied organ involvement due to heteroplasmy. Thus, the disorders included under the rubric "inherited bone marrow failure syndromes" have clinical. hematologic, oncologic, and genetic diversity.
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PMID:Bone marrow failure syndromes in children. 1243 Jun 21

Impaired platelet production may result from four mechanisms: 1) marrow hypoplasia, 2) ineffective thrombopoiesis, 3) aberration of thrombopoietic regulation and 4) hereditary thrombocytopenia. Megakaryocytic hypoplasia(reduced numbers of megakaryocytes) is seen in a wide variety of disorders including aplastic anemia, radiation, drugs such as chemotherapeutic agents, infiltrative neoplasms of the marrow, acquired amegakaryocytic thrombocytopenic purpura, paroxysmal nocturnal hemoglobinuria(PNH), and Fanconi's anemia. Ineffective thrombopoiesis(normal to increased numbers of megakaryocytes) is recognized in megaloblastic anemia and myelodysplastic syndrome. Disorders of thrombopoietic control are uncommon and seen in cyclic thrombocytopenia and thrombocytopenia with absent radii. Hereditary thrombocytopenia is overall a very rare disorder, and may be inherited as an X-linked recessive trait, an autosomal dominant trait, or autosomal recessive trait. It is important to recognize hereditary thrombocytopenia because clinically they resemble ITP, but the patients do not respond to steroid treatment or splenectomy.
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PMID:[Thrombocytopenia due to deficient platelet production]. 1271 78

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome exhibiting considerable clinical and genetic heterogeneity. X-linked recessive, autosomal dominant and autosomal recessive forms are recognised. The gene mutated in X-linked DC (DKC1) encodes a highly conserved nucleolar protein called dyskerin. Dyskerin associates with the H/ACA class of small nucleolar RNAs which are important in guiding the conversion of uracil to pseudouracil in ribosomal RNA. Dyskerin also associates with the RNA component of telomerase (hTR) which is important in the maintenance of telomeres. Mutations in hTR were recently demonstrated in patients with autosomal dominant DC and in a subset of patients with aplastic anaemia (AA) but without other diagnostic features of DC. This discovery demonstrates that both DC and a subset of AA are due to a defect in telomerase. The link between DC and AA and in turn to defective telomerase suggests that treatments directed at correction of telomerase activity might benefit DC/AA patients who do not respond to conventional therapy.
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PMID:Dyskeratosis congenita: its link to telomerase and aplastic anaemia. 1455 76

Hoyeraal-Hreidarsson syndrome represents a severe variant of dyskeratosis congenita (Zinsser-Cole-Engman syndrome). This X-linked recessive, progressive, multisystemic disorder reported so far in 12 pedigrees is characterised by intrauterine growth retardation, microcephaly, cerebellar hypoplasia, mental retardation, progressive combined immune deficiency and aplastic anaemia. Mutations in the DKC1gene on Xq28 have been identified in the X-linked form of dyskeratosis congenita and in some Hoyeraal-Hreidarsson syndrome patients. We report on two sibs and two other unrelated patients with the striking clinical features of Hoyeraal-Hreidarsson syndrome. Noticeably, all four had early digestive problems, with chronic, bloody diarrhoea and feeding problems causing one of the most difficult problems in the supportive treatment of this uniformly lethal condition. Pathological changes in the proliferative compartment of the digestive mucosa included alterations of the glandular architecture and focal rarefaction of the glands. This aspect seems consistent with altered telomerase function associated with a dyskerin mutation which may decrease the proliferative capacity of digestive epithelial cells. A missense mutation 146 C-->T (Thr49Met) in the DKC1gene was found in two unrelated patients, whereas mutation screening was negative for one single case. The absence of mutations of the DKC1gene in patients with Hoyeraal-Hreidarsson syndrome emphasises the probable implication of one or more other loci.
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PMID:Further delineation of the congenital form of X-linked dyskeratosis congenita (Hoyeraal-Hreidarsson syndrome). 1464 17


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