Puslapis 1 nuo 44 rezultatus
A genomic phage library was constructed using lymphocyte DNA from a patient with cross-reacting material-positive, moderately severe hemophilia B. The library was screened by using a full-length factor IX cDNA as a hybridization probe. DNA sequence analysis of the factor IX exons and intron/exon
Factor IX is a multidomain protein and is the proenzyme of a serine protease, factor IXa, essential for hemostasis. In this report, we describe the molecular basis of hemophilia B (deficiency of factor IX activity) in five patients who have neither deletions nor rearrangements of the factor IX gene.
Essential to hemostasis is the interaction of factor IXa with factor VIIIa. Recent studies indicate that helix-330 in the protease domain of factor IXa provides a critical binding site for factor VIIIa. Although weaker interactions cannot be ruled out, a primary role of the EGF1 domain of factor IXa
A patient with severe haemophilia B with a glycine-to-valine missense mutation at residue 190 (c25, chymotrypsin numbering) in factor IX (FIX; FIX-G190V or FIX-FuChou) had <1% of normal FIX clotting activity and 36% of normal FIX antigen levels (cross-reacting material- reduced, CRMr). Residue 190
Molecular characterization of hemophilia B at gene level has become an indispensable tool for a proper genetic counseling in carriers and for a closer surveillance of inhibitor development in several severe forms. Our study was aimed at characterizing the molecular defects in the factor IX (FIX)
Previous studies revealed that cleavage at Arg-318-Ser-319 in the protease domain autolysis loop of factor IXa results in its diminished binding to factor VIIIa. Now, we have investigated the importance of adjacent surface-exposed helix 330-338 (162-170 in chymotrypsin numbering) of IXa in its
Factor IX is a vitamin K-dependent serine protease, which exists as a zymogen in the blood. On activation to factor IXa, by factor XIa or tissue factor-factor VIIa complex, it forms tenase complex with factor VIIIa, in the presence of Ca2+. This tenase complex enzymatically converts factor X to
We studied the functional role of two mutations, Pro55Ser and Pro55Leu, located in the N-terminal Epidermal Growth Factor-like domain (EGF1) of coagulation factor (F) IX. Both mutations cause mild hemophilia B with habitual FIX coagulant activities of 10-12% and FIX antigen levels of 50%. We found
Hemophilia B is an X-linked bleeding disorder caused by the absence or reduced activity of coagulation factor IX (FIX). Here, we report a double mutation in the FIX gene (F9) in a Japanese patient with severe hemophilia B. FIX activity (FIX:C) was measured with a one-step functional assay. FIX
Development of inhibitory antibodies is a serious complication of treatment with repeated factor IX infusions in a minority of patients with hemophilia B. Such antibodies detected in 8 patients have been characterized. Typing studies revealed that patients' immune response toward factor IX is highly
Hemophilia B (HB) is a recessive X-linked inherited disorder, the pathogenesis of HB is deficiency or functional abnormalities of coagulation factor IX, which is caused by F9 gene mutations. To explore the mechanism of its molecular pathology, 40 patients with HB were studied with polymerase chain
Hemophilia B is an X-linked recessive bleeding disorder resulting from a deficiency of the coagulation factor IX (FIX) protein activity, a vitamin K-dependent serine protease active in both the intrinsic and extrinsic coagulation systems. DNA analyses of the factor IX gene in two unrelated patients
Rapid identification of gene defects allows definite carrier and prenatal diagnosis in virtually every family with haemophilia B. We report a study of the family of an isolated patient. Analysis of all the essential regions of the patient's factor IX gene (promoter, exons, transcript processing
Cumulative evidence has shown that a delicate balance between serine proteases and their inhibitors is crucial for normal functioning of several biological pathways. The importance of proteases and their inhibitors is well documented in several human diseases. Among them, the best documented are
The factors responsible for the removal of injected factor IX (fIX) from the blood of individuals with haemophilia B are only partly understood, and may include binding to endothelial or subendothelial sites, passive extravasation related to size or charge, or interactions requiring fIX activation.