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)

The effect of the enzymes phospholipases C and D on Factor VIII were investigated. Phospholipase D was found to activate the partially purified intact Factor-VIII molecule maximally at a final concentration of 0.6 U/ml. Neither the dissociated small molecular weight component nor the high molecular weight component were activated. Phospholipase C, on the other hand, inactivated both the intact and the dissociated Factor-VIII molecule. Phospholipase D, however, had no effect on the haemophilic cryoprecipitate or the partially purified haemophilic Factor VIII. The implications of these results for the genetic control of the Factor-VIII molecule are discussed. In this connection, haemophilia A is hypothesized to be caused by an X-linked enzyme effect that impairs phospholipid assembly of the Factor-VIII protein, whereas von Willebrand's disease might be due to a structural defect of the Factor-VIII protein.
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PMID:Effect of phospholipases on factor-VIII activity. 30 30

A plasma von Willebrand factor (vWf) defect limited to its failure to bind factor VIII (FVIII) was previously characterized in a woman with FVIII deficiency and normal primary haemostasis. By using in vitro tests we found a similar pattern in three siblings of another family previously thought to be affected with mild haemophilia A. Furthermore, a decrease in vWf ability to bind FVIII was found in the parents and the brother of the three patients. This decrease was consistent with heterozygous expression of a recessive vWf gene abnormality. FVIII deficiency was corrected by infusion with a vWf concentrate almost devoid of FVIII coagulant activity. FVIII recovery and half-life thus obtained showed that this treatment was more effective than a FVIII infusion performed by way of comparison. These results indicate that this vWf defect may account for FVIII deficiency in patients without the usual laboratory and clinical features of von Willebrand's disease. Changes in therapy and genetic counselling following the new diagnosis in this family emphasize the need to search for such a vWf defect in patients in whom FVIII deficiency is not obviously X-linked.
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PMID:Evidence for a von Willebrand factor defect in factor VIII binding in three members of a family previously misdiagnosed mild haemophilia A and haemophilia A carriers: consequences for therapy and genetic counselling. 212 99

A review is given of the history and distribution of hemophilia in dogs. The current knowledge of Factor VIII relative to hemophilia A and von Willebrand's Disease is presented. The tests required for distinguishing between hemophilia A, hemophilia B, von Willebrand's Disease, and various disorders caused by other factor defects in the coagulation cascade are described. X-linked, recessive inheritance of hemophilia A is illustrated in genealogical diagrams. The precautions required in connection with blood sampling for diagnostic tests are emphasized.
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PMID:Hemophilia in dogs, with special reference to hemophilia A among German shepherd dogs in Denmark. I: Pathophysiology, laboratory tests and genetics. 643 87

The differential diagnosis of the genetic bleeding disorders, hemophilia A and von Willebrand disease, is occasionally confounded by the close molecular relationship of coagulation factor VIII and von Willebrand factor (vWF). This report describes the autosomal inheritance of a hemophilia A phenotype due to a mutation of vWF that results in defective factor VIII binding. The proband was a female patient with low levels of factor VIII activity. Polymerase chain reaction (PCR) amplification and DNA sequencing were employed to examine exons encoding the putative factor VIII binding domain of vWF. The patient was found to be homozygous for a single point mutation causing a Thr-->Met substitution at amino acid position 28 in the mature vWF subunit. The phenotypic expression of the mutation was determined to be recessive because heterozygous family members were clinically unaffected. Recombinant vWF containing the observed amino acid substitution was expressed in COS-1 cells. The mutant vWF was processed and secreted normally, and was functionally equivalent to wild-type vWF in its ability to bind to platelets. However, the mutant failed to bind factor VIII, demonstrating that the mutation was functionally related to the observed hemophilia phenotype. The family we describe demonstrates the recessive inheritance of a recently recognized class of genetic bleeding disorders, we call "autosomal hemophilia." We conclude that vWF mutation may be an under recognized cause of hemophilia, especially in cases where the inheritance pattern is not consistent with X-linked transmission.
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PMID:Autosomal recessive transmission of hemophilia A due to a von Willebrand factor mutation. 850 Jul 91

Diagnosis of von Willebrand disease Type 2N (vWD 2N), which mimics hemophilia A and its carrier state, is important for accurate genetic counseling and appropriate therapy. To make testing for the disorder more clinically applicable, we developed a simplified method for measurement of factor VIII (FVIII) binding to von Willebrand factor (vWF) using commercially available reagents and standard clinical assays. FVIII binding to vWF was measured by capture of patient vWF by polyclonal antibodies on cyanogen bromide-activated Sepharose beads, reaction with recombinant FVIII, and assay of unbound FVIII by clotting methods. Unbound vWF was measured in patient plasma after capture by the Laurell method. The ratio of bound FVIII/bound vWF was normal in hemophilia A, vWD Type 1, and vWD Type 3 patients, and abnormal in 5 subjects from two families, all of whom had vWD 2N mutations. Patient 1, with FVIII 8 U/dl, vWF: Ag 61 U/dl, vWF:RC 74 U/dl, and FVIII binding nil, was homozygous for the Arg91 Gln mutation. She was followed during pregnancy and delivered an unaffected heterozygous son. Patient 2 had FVIII 8 U/dl, vWF:Ag 73 U/dl, and vWF:RC 71 U/dl, and very low FVIII binding. She was heterozygous for Arg91Gln, as were her mother and sister; no second vWD 2N mutation was found. Her brother, with FVIII 14 U/dl, vWF:Ag 113 U/dl, and vWF:RC 72 U/dl, has no evidence of vWD 2N. With an X-linked inheritance pattern of bleeding tendency, this family is the first reported with combined hemophilia A and vWD 2N.
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PMID:Diagnosis of von Willebrand disease type 2N: a simplified method for measurement of factor VIII binding to von Willebrand factor. 969 96

Evaluating the factor VIII (FVIII) binding activity of von Willebrand factor (VWF) is an important step in the diagnostic work-up of families affected by apparent mild haemophilia A. In von Willebrand's disease (VWD) type 2N (Normandy), mutations at the N-terminal end of the mature VWF subunit gene prevent the binding of FVIII. Individuals heterozygous for type 2N VWD are generally asymptomatic. Homozygotes and compound heterozygotes present with a clinical picture which mimics haemophilia A, with a markedly reduced FVIII : C activity and VWF within the normal range, but instead of exhibiting X-linked inheritance they show an autosomal recessive inheritance pattern. The distinction between haemophilia A and VWD type 2N has important implications for therapy and genetic counselling. We present a highly specific enzyme-linked immunosorbent assay screening method for the Normandy variant, which measures VWF : FVIII binding activity in parallel with VWF antigen, using monoclonal capture and detection antibodies. The assay is fully automated using a robotic microtitre plate processor, requiring minimal user intervention and providing the capacity to screen large numbers of patients.
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PMID:Evaluation of an automated screening assay for von Willebrand disease type 2N. 1245 18

Inherited deficiencies of plasma proteins involved in blood coagulation generally lead to lifelong bleeding disorders, whose severity is inversely proportional to the degree of factor deficiency. Haemophilia A and B, inherited as X-linked recessive traits, are the most common hereditary hemorrhagic disorders caused by a deficiency or dysfunction of blood coagulation factor VIII (FVIII) and factor IX (FIX). Together with von Willebrand's disease, a defect of primary haemostasis, these X-linked disorders include 95% to 97% of all the inherited deficiencies of coagulation factors. The remaining defects, generally transmitted as autosomal recessive traits, are rare with prevalence of the presumably homozygous forms in the general population of 1:500,000 for FVII deficiency and 1 in 2 million for prothrombin (FII) and factor XIII (FXIII) deficiency. Molecular characterization, carrier detection and prenatal diagnosis remain the key steps for the prevention of the birth of children affected by coagulation disorders in developing countries, where patients with these deficiencies rarely live beyond childhood and where management is still largely inadequate. These characterizations are possible by direct or indirect genetic analysis of genes involved in these diseases, and the choice of the strategy depends on the effective available budget and facilities to achieve a large benefit. In countries with more advanced molecular facilities and higher budget resources, the most appropriate choice in general is a direct strategy for mutation detection. However, in countries with limited facilities and low budget resources, carrier detection and prenatal diagnosis are usually performed by linkage analysis with genetic markers. This article reviews the genetic diagnosis of haemophilia, genetics and inhibitor development, genetics of von Willebrand's disease and of rare bleeding disorders.
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PMID:Genetic diagnosis of haemophilia and other inherited bleeding disorders. 1668 1

The authors describe a girl diagnosed as having Coats' disease, Turner syndrome (45X karyotype), and type 1 von Willebrand disease. She tested negative for the Norrie disease pseudoglioma (NDP) gene located on the X-chromosome, which has been suspected of contributing to Coats' disease.
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PMID:Coats' disease, Turner syndrome, and von Willebrand disease in a patient with Wildtype Norrie disease pseudoglioma. 2041 71

Hemophilia A is an X-linked, recessive disorder resulting from mutations in the f8 gene. Here we report the rare case of a female compound heterozygote with mild factor VIII deficiency (fVIII:C 9%) and moderate phenotype. On investigation she was confirmed to have normal Von Willebrand factor studies with a 46XY genotype. Further genetic testing revealed 3 mutations in the f8 gene: 1 novel missense mutation (c.6142T>G), 1 novel in-frame deletion (c.1281_1292del), and another missense mutation of unclear significance (c.3780C>G). Both parents had normal coagulation profiles; however, the 2 novel mutations were present in the patient's mother and the known missense mutation was present in her father. This unusual case demonstrates the utility in genetic analysis for f8 gene mutational analysis and suggests a compound effect of the 3 identified mutations as a cause for factor deficiency.
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PMID:Novel Mutations Resulting in a Moderate to Severe Phenotypic Manifestation of Hemophilia A in a Female. 2845 55

The World Federation of Hemophilia (WFH) states in its Guidelines for the Management of Hemophilia, Second Edition [1], that people with hemophilia are best managed in a comprehensive care setting. That team is typically comprised of a core group including a hematologist, nurse coordinator, physiotherapist, social worker, specialized lab technologist and data manager, and as needed, by other specialists. Hemophilia is an X-linked congenital bleeding disorder caused by a deficiency of coagulation factor VIII (FVIII) in hemophilia A or factor IX (FIX) in hemophilia B. There are a number of other disorders that are now typically treated in these comprehensive care centers including von Willebrand disease (VWD), rare factor deficiencies (I, II, V, V & VIII, VII, X, XI and XIII), and inherited platelet function disorders. Models of comprehensive care delivery for hemophilia and other inherited bleeding disorders were first defined in the 1960s and have been in constant evolution ever since. Comprehensive care for hemophilia and other inherited bleeding disorders was made possible by the discovery of cryoprecipitate for the treatment of hemophilia A in the mid-1960s and, in the decade that followed, the development of lyophilized clotting factor concentrates. It was quickly realized that treatment at home was far preferable to frequent visits to Emergency Departments or out-patient. Tragically, the same clotting factor concentrates that revolutionized treatment and dramatically improved quality of life exposed thousands of people with hemophilia to HIV-AIDS and hepatitis C in the late 1970s and 1980s [2]. The model of comprehensive care was forced to add specialists in infectious disease and hepatology. At the same time, the crisis accelerated the development of recombinant FVIII and IX clotting factors; these entered the clinic in 1993 and 1997 respectively. The proven safety of both recombinant and plasma-derived products spurred on the expansion of prophylactic care to more patients. Today, with the success of a comprehensive care model that keeps patients out of the hospital (and out of sight), and promises a normal lifespan, there is an emerging impression among many health system managers that the problem of hemophilia is "solved." In 2019, however, even the best care and treatment remains highly burdensome and not entirely efficacious. Emerging innovative therapies are promising yet dramatically different in their modes of action, dosing and administration. Much of what has been learned in terms of management of the disease over the last 50 years may no longer be relevant. Rather than one type of treatment for all, there may well be many different therapies. Comprehensive care centres will not become obsolete. It will remain critically important that specialized staff be able to foster long-term relationships with patients and their families. Indeed, they will need to expand their knowledge and expertise in order to be able to continue to deliver the standards of care so carefully developed since the 1960s.
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PMID:Comprehensive care for hemophilia and other inherited bleeding disorders. 3142 62


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