Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0684275 (haemophilia)
 10,958 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of factor VIII:C inhibitors remains one of the most serious complications of repeated transfusion in patients with haemophilia A. The proportion of patients affected has been reported to range from 3.6% to 25%, but these figures have been derived mainly from retrospective data and from total numbers of known haemophiliacs instead of number at true risk. The assessment here is based on a prospective study, started in 1976, on the incidence of inhibitor development in haemophiliacs born after 1970 whose FVIII or FIX activity was 5% or less, and who had received replacement therapy at least once. 46 of 63 children with haemophilia A and 13 of 17 with haemophilia B fulfilled the enrollment criteria. Inhibitors developed only in haemophilia A patients who had previously been treated with FVIII products--inhibitor concentrations were high in 12 and low in 3. Inhibitors developed in 24% (15/63) of all haemophilia A patients, and in 52% (14/27) of those with severe disease. The incidence of inhibitor development for all haemophilia patients was 39.1 per 1000 patient-years of observation. All inhibitors were first detected when patients were aged 0.08-5.2 years. The cumulative risk was 33% at age 6 years. The findings indicate that previous reports have underestimated the risk of acquiring FVIII inhibitors. Prospective, standardised studies, especially in children, are needed for the assessment of the true risk of this complication.
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PMID:Incidence of development of factor VIII and factor IX inhibitors in haemophiliacs. 135 Dec 35

The common restriction fragment length polymorphisms (RFLPs) associated with the FIX gene: 5' BamH I, Dde I, BamH I (2), Taq I and 3' Hha I were absent or of low incidence in Southern Chinese and are therefore not useful for linkage analysis. No deletion was detected amongst seven consecutive unrelated haemophilia B patients, but one had an insertion of a 15 kb Pvu II fragment containing exon d. Using an alternate strategy of polymerase chain reaction (PCR) amplification and direct sequencing, the molecular defect in the other six patients was defined. The four novel mutations characterized were: nucleotide (nt) 6410 G----C (Gly12----Ala); nt 31261 delta T (stop codon 31 bp downstream); nt 31260 C----G (Thr380----Ser) and nt 31122 C----A (Ala34----Asp). Two patients had the same mutation at nt 6365, G----A (Arg-4----Gln), identical to one previously described in other ethnic groups, suggesting that this is a hotspot for mutation. Each of the mutations was found to affect an enzyme recognition site and could thus be identified by direct visualization of abnormal restriction fragments in amplified genomic DNA. This allows rapid and accurate DNA diagnosis of haemophilia B in an ethnic group which otherwise shows little or no polymorphism for the common RFLP sites.
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PMID:Molecular defects in haemophilia B: detection by direct restriction enzyme analysis. 168 Mar 73

An increasing amount of evidence suggests that coagulation factors VIII and IX play a role not only in the intrinsic but also in the extrinsic pathway of coagulation. In this context the influence of the Extrinsic Pathway Inhibitor (EPI) on the coagulation time of hemophilia plasma lacking FVIII or FIX has been investigated. The coagulation time was measured in a dilute thromboplastin assay. Addition of recombinant EPI (rEPI) prolonged the coagulation time of normal plasma while the addition of an inhibitory antibody against EPI shortened the coagulation time. At low concentrations of thromboplastin the coagulation time of hemophilia plasma was prolonged and at all dilutions of thromboplastin, addition of anti-EPI IgG normalized the coagulation time of a hemophilia plasma. Analysis of 10 individual donor plasma samples and 8 individual hemophilia samples showed that addition of anti-EPI IgG shortened the coagulation time more in hemophilia plasma than in normal plasma. This illustrates the importance of a powerful extrinsic FVII dependent pathway to achieve hemostasis in the case of FVIII or FIX deficiency (hemophilia A and B).
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PMID:Inhibition of extrinsic pathway inhibitor shortens the coagulation time of normal plasma and of hemophilia plasma. 179 97

Recombinant FVIIa is being developed for treatment of haemophiliacs with antibodies against FVIII/FIX. rFVIIa was shown to be haemostatically active in haemophilia A and B dogs as well as in 20 haemophilia patients (one haemophilia B and 19 haemophilia A patients). Thirteen patients were treated for life-threatening bleedings and nine at surgery (dose: 60-90 micrograms/kg q 3-4 h). One patient underwent synovectomy in a knee joint under the cover of rFVIIa as the sole coagulation factor without any problems. One patient with FXI deficiency was successfully treated at an orchidectomy. The haemophilia B patient was treated in association with a compartment syndrome (surgical fasciotomy) with a complete haemostasis. He later uneventfully underwent skin grafting. Two CNS bleeds, a severe mouth bleed were treated as well as an extensive nasopharyngeal bleed in a patient with an acquired inhibitor against FVIII. Shortening of the prothrombin time as well as of the APTT was seen. No side-effects were observed. It is speculated whether FVIIa in complex with not only tissue factor but also phospholipids exposed at the site of injured cells directly activates FXa and thereby the final common pathway of the coagulation cascade.
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PMID:Factor VIIa in the treatment of haemophilia. 210 15

The genetic basis of a mild form of haemophilia Bm has been investigated. The patient under investigation has a mild bleeding disorder and has never experienced spontaneous bleeds. Factor IX coagulant activity (FIX:C) was 0.15 units/ml and factor IX antigen (FIX:Ag) 1.32 units/ml. The prothrombin time performed with an ox brain thromboplastin was 65 s (normal plasma 31 s). Studies of the abnormal factor IX protein in this patient showed a normal molecular weight and normal calcium binding properties. Activation of the mutant factor IX with factor XIa showed normal proteolytic cleavage. DNA sequence from the eight factor IX exons and flanking introns was amplified from this patient using the polymerase chain reaction. The amplified material was subjected to direct chain termination nucleotide sequencing. The only nucleotide sequence alteration found was a G----C transversion at nucleotide 20,524, changing the amino acid encoded at residue 182 from valine to leucine. This residue is one amino acid removed from the beta cleavage site of factor IX. This residue is highly conserved in other vitamin K dependent serine proteases and we propose that its alteration in this patient is responsible for his mild haemophilic phenotype, and for the abnormal interaction of this factor IX protein with the extrinsic system of coagulation.
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PMID:A mutation adjacent to the beta cleavage site of factor IX (valine 182 to leucine) results in mild haemophilia Bm. 237 9

A simple method for analyzing the activation mechanism of FIX in patients with hemophilia B variants is described. The procedure consists of rapid partial purification of FIX by BaCl2 adsorption-elution from only 3 ml of plasma, incubation with FXIa/Ca2+, SDS-PAGE, western blotting and subsequent autoradiography using monoclonal anti-FIX antibody. Abnormal FIX from the plasma of 7 unrelated patients with hemophilia BR, B+ or BM was investigated. A time course study showed that FIX in the patient with hemophilia BM (Nagoya I), BM (Nagoya II) and B Kawachinagano seemed not to be cleaved by FXIa, FIX in the patient with hemophilia B Kashihara was partially cleaved, FIX in the patient with hemophilia BM (Takatsuki) showed delayed cleavage, and that FIX in the patient with hemophilia BM (Niigata) and BM (Kiryu) was cleaved completely at a rate similar to normal FIX. These findings were identical to those previously observed for the respective factors in a purified system. The procedure used here is useful for screening for a defective activation mechanism of abnormal FIX.
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PMID:A simple method for analyzing factor IX activation in the patients with hemophilia B variants. 349 81

An agarose plate method for detecting human alloantibodies (inhibitors) to coagulant factor IX has been developed. The assay is based on the ability of such antisera to inhibit the coagulation of a mixture of haemophilia B plasma, normal plasma and platelet subsitute in an agarose matrix. The agarose plate method was also adopted to measure levels of FIX antigen (IX:Ag) in plasma. Using this technique, 12 of 17 obligate carriers of haemophilia B demonstrated reduced levels of IX:Ag. Three of the five carriers with normal IX:Ag levels were members of kindred in which affected individuals had normal or near normal levels of IX:Ag.
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PMID:An agarose plate method for detecting alloantisera to coagulant factor IX and factor IX antigen. 737 2

Patients with the haemophilia B Leyden phenotype show a distinct pattern of factor IX expression characterized by a post-pubertal increase in FIX levels and the remission of clinical symptoms in adult life. This phenotype has previously been linked to single base mutations within transcription factor binding sites in a region of approximately 40 bp around the major start point of transcription of the FIX gene. Here we report a novel mutation in this region within the transcription factor C/EBP binding site at +1 to +18. The mutation is a single base pair deletion from a triplet of thymine residues at +6 to +8. We show that the extent to which this mutation disrupts the binding of C/EBP to its binding site is less marked than the disruption caused by the +13 A-->G mutation of FIX Norwich (1). This correlates with age-matched phenotypic data we have available for the patient reported here and that of FIX Norwich.
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PMID:A single base pair deletion in the promoter region of the factor IX gene is associated with haemophilia B. 774 Apr 44

The frequency of five factor VIII gene intragenic and linked DNA polymorphisms and five factor IX gene intragenic polymorphisms was studied in Thai females. The polymorphisms in the FVIII gene were detected by restriction enzymes BclI, XbaI, BglI and at linked loci DX13 (DXS15) and St14 (DXS52) by BglII and TaqI, respectively, and in the FIX gene by MseI, DdeI, XmnI, TaqI and HhaI. With the exception of the BglI restriction fragment length polymorphism (RFLP), which is absent in Thais, factor VIII polymorphism frequencies were similar in Thais and Caucasians. Combined use of XbaI and TaqI/St14 resulted in a heterozygosity rate of greater than 90% in Thai females. For FIX, the recently described MseI RFLP in the 5' flanking region was the most informative polymorphism in Thais, 43% of females being heterozygous. The other four polymorphisms added little to the overall heterozygosity rate. The appropriate polymorphisms were used to track defective factor VIII and IX genes through 22 Thai pedigrees with haemophilia to enable carrier status to be assigned to female family members. The information obtained during this study will form the basis for carrier detection and prenatal diagnosis of haemophilia A and B by DNA polymorphism analysis in Thailand.
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PMID:A comparison of the allelic frequencies of ten DNA polymorphisms associated with factor VIII and factor IX genes in Thai and Western European populations. 791 50

Monoclonally purified factor concentrates have been available for hemophilia treatment since the late 1980's. They are biochemically characterized by a high-degree of clotting factor (FVIII or FIX) purification and by the virtual lack of contaminants (immunoglobulins, fibrinogen and fibronectin). The purification procedure sharply reduces the viral load and increases the safety of the concentrate because of the viral inactivation procedures. Viral safety is demonstrated by prospective studies in previously untreated patients as well as by the huge amount of concentrates produced and used so far without reports of untoward side effects. Monoclonal concentrates are also safe in terms of inhibitor production: they do not elicit the appearance of inhibitors to either FVIII or FIX with increased frequency, as shown by data in published prospective studies. Prospective studies have recently demonstrated that the long-term administration of these high purity concentrates does not exert any side effects on the immune system in HIV-positive hemophiliacs. The FIX concentrate is also extremely safe in terms of thrombotic complications: the highly pure FIX does not activate blood coagulation. It has been shown that the monoclonally purified FIX concentrate caused no thrombotic events in high-risk surgical patients who had previously experienced such complications while on Prothrombin Complex Concentrates.
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PMID:Immunopurified clotting factor concentrates. 817 18


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