Stuart clotting defect. I. Segregation of an hereditary hemorrhagic state from the heterogeneous group heretofore called stable factor (SPCA, proconvertin, factor VII) deficiency

Congenital factor X deficiency: spectrum of bleeding symptoms in 32 Iranian patients

The spectrum of the clinical manifestations of congenital factor X deficiency was studied in 32 Iranian patients. The most frequent symptom was epistaxis, which occurred in 72% of patients, with all degrees of deficiency. Other mucosal haemorrhages (e.g. haematuria, gastrointestinal bleeding) were less frequent and occurred mainly in patients with unmeasurable factor X. Menorrhagia occurred in half of the women of reproductive age. Soft tissue bleeding occurred in two-thirds of the patients; spontaneous haematomas and haemarthroses led to severe arthropathy in five patients. Bleeding from the umbilical stump was an unexpected finding in nine patients. This study demonstrated that the bleeding tendency of factor X deficiency is severe and correlates with factor levels.

A functional factor X deficiency

A functional factor X deficiency is described which caused pronounced reduction in the in vitro activation of the extrinsic system while marginally affecting the in vitro activation of the intrinsic pathway. All studies were normal with the exception of a prolonged PT, an elevated factor X antigen, and low factor X activity. Western blot analysis revealed the presence of two factor X species. The abnormal molecule was of higher molecular weight. Interestingly, there was no bleeding associated with this deficiency. The biochemical basis of this defect is currently under investigation.

Biochemistry of factor X

Factor X circulates as a serine protease which is converted to the active form at the point of convergence of the intrinsic and extrinsic coagulation pathways. Subsequently, the enzymatic species, factor Xa, is involved in macromolecular complex formation with its cofactor factor Va, a phospholipid surface and calcium to convert prothrombin into thrombin. The gene encoding factor X shares a number of structural and organisational features in common with the other vitamin K-dependent coagulation proteins, suggesting that they have evolved from a common ancestral gene. Each of the exons encoding these proteins can be considered as a module coding for a homologous domain in each protein. These structural domains in factor X are responsible for specific functional properties including gamma-carboxylase recognition, calcium binding, phospholipid surface interaction, as well as cofactor and substrate binding. Studies of recombinant proteins and proteolytic fragments continue to provide significant insight into structure-function relationships of the protein modules within factor X.

Factor XSanto Domingo. Evidence that the severe clinical phenotype arises from a mutation blocking secretion

Factor X (FX) is a vitamin K-dependent plasma protein required for the intrinsic and extrinsic pathways of blood coagulation. FXSanto Domingo is a hereditary FX deficiency which is characterized clinically by a severe bleeding diathesis. The proposita has a FX activity of less than 1% and a FX antigen of less than 5%. We have determined the molecular basis of the defect in the FXSanto Domingo gene by amplification of all eight exons with polymerase chain reaction and subsequent sequence analysis. The patient is homozygous for a G----A transition in exon I at codon -20 (numbering the alanine at the NH2 terminus of the mature protein as +1), resulting in the substitution of arginine for glycine in the carboxy-terminal part of the signal peptide. This amino acid change occurs near the presumed cleavage site of the signal peptidase. We hypothesized that the mutation might prevent cleavage by the signal peptidase which in turn would impair proper secretion of the FX protein. To test this hypothesis, we compared the expression of wild type and mutant FX cDNA in a human kidney cell line. Wild type and mutant constructs in the expression vector pCMV4 were introduced into the human embryonic kidney cell line 293 by calcium phosphate transfection. FX antigen levels in the supernatant of the cells harboring the wild type construct were 2.4 micrograms/10(7) cells per 24 h, whereas antigen levels in media from cells containing the FXSanto Domingo construct were undetectable. No FX antigen was detected in the cell lysates of cells transfected with the mutant construct. To insure that the difference in protein levels was not due to a difference in steady state levels of mRNA, Northern analysis was performed on RNA from the cell lysates of both constructs. The results showed a transcript of the same size, present in roughly equal amounts, in both cases. Thus, the defect in the signal sequence of FXSanto Domingo exerts its effect posttranscriptionally. FXSanto Domingo is the first described example of a bleeding diathesis due to a mutation in the signal sequence.

Inherited bleeding disorders

Congenital bleeding disorders comprise a heterogeneous group of diseases that reflect abnormalities of blood vessels, coagulation proteins and platelets. Studies of these diseases, many of which are rare and several of which result in a mild bleeding diathesis only, have significantly increased our understanding of normal haemostasis. Two lessons have been learned. First, quantitative abnormalities of coagulation proteins and platelets are an important, but not the only, cause of significant haemorrhage; some cases of inherited bleeding disorders reflect synthesis of a dysfunctional coagulation protein or production of abnormal platelets. Diagnostic tests that reflect qualitative abnormalities are therefore important in the evaluation of selected patients with inherited bleeding disorders. Second, in occasional patients the inherited disorder is complex and reflects combined abnormalities of coagulation proteins alone or in association with platelet disorders. In clinical practice it is useful to distinguish disorders that cause significant clinical bleeding from those that cause few or no symptoms. Examples of the former include severe deficiencies of factors VIII and IX, and the homozygous forms of factor II, V, VII, X, XI, XIII, fibrinogen and von Willebrand factor. Comparable platelet disorders include the inherited thrombocytopenias with platelet counts less than 20 x 10(9) litre-1 and the homozygous forms of Bernard-Soulier syndrome and Glanzmann's thrombasthenia. The most frequently encountered mild haemostatic abnormalities include type I von Willebrand's disease, the platelet storage pool deficiency syndromes and the mild and moderate forms of haemophilia A and B; occasionally heterozygous or homozygous forms of the rarer coagulation disorders, e.g. factor XI deficiency, may present with a mild bleeding diathesis. Finally, some disorders are entirely asymptomatic, e.g. factor XII deficiency and deficiencies of other contact coagulation factors. Management of patients with inherited bleeding disorders should reflect knowledge of the specific disorder to be treated plus careful consideration of the clinical circumstance for which therapy is proposed. In all cases, once a decision to treat has been made, the safest efficacious therapy should be given (for example DDAVP in the treatment of patients with mild haemophilia A or type I von Willebrand's disease). Although blood products are now much safer and the risk of blood transmitted viral infections is low, there still remains a risk that transfusion of any blood product may be associated with serious side-effects. As a result, therapy should be given only after careful consideration of the risk: benefit ratio and not merely to treat an abnormal laboratory result.(ABSTRACT TRUNCATED AT 400 WORDS)

Novel factor X deficiency. Normal partial thromboplastin time and associated spindle cell thymoma

This report presents a heretofore undescribed laboratory variant of congenital factor X deficiency, seen in conjunction with a relatively rare tumor. The patient had a history of bleeding, a prolonged prothrombin time, and a factor X value of 4.2 percent of normal activity, but the partial thromboplastin time and Russell's viper venom clotting time were normal. Management of this case required unusual measures to treat the patient's coagulopathy.

Heterogeneity of hereditary and acquired factor X deficiencies by combined immunochemical and functional analyses

Limited information is available regarding molecular abnormalities associated with derived factor X deficiencies. In order to assess the types of molecular aberrations that may occur in this group of haemostatic diseases we have analysed plasmas of 33 individuals from 28 kindred exhibiting factor X deficiency. These included those of hereditary type, transiently acquired deficiency as well as factor X deficiency associated with amyloidosis. Plasmas were analysed by one-stage assays for factor X activation by the extrinsic coagulation pathway, intrinsic coagulation pathway and Russell's viper venom. Selected plasmas were analysed in two-stage assays. Normal factor X concentration by specific radioimmunoassay was 6.38 +/- 1.29 micrograms/ml. Factor X associated with factor X deficiency were grouped by their specific activities measured for the three activation pathways and antigen concentration. The results suggest that a broad spectrum of molecular aberrations exist in the factor X deficiency states. The most common group of factor X deficiency was associated with abnormal activation of factor X by all three pathways. Variants of factor X associated with primary amyloidosis and transient acquired deficiency appeared to be abnormal molecules and not just reduced factor X concentration. Hereditary abnormal factor X molecules include the spectrum of potential defective molecules. The relationship of factor X structure to function and the heterogeneity of these defective molecules is discussed.

Inherited factor X deficiency: presentation of a case with etiologic and treatment considerations

The first documented case of inherited factor X deficiency in the dental literature is presented. Its ascertainment as a result of postoperative surgical complications illustrates the clinician's need to be familiar with the hereditary bleeding diatheses, as treatment is dependent on the underlying etiology of the specific disorder. In the present case treatment included administration of the antifibrinolytic agent epsilon-aminocaproic acid (EACA) and fresh frozen plasma. On the basis of our findings, a minimal therapeutic level of circulating factor X is estimated to be 15 percent of the normal level. Genetic heterogeneity within the factor X deficiency phenotype is discussed and, on the basis of laboratory findings, a CRM-positive autosomal recessive structural or regulator gene defect is proposed as the etiologic factor in the current case. Forty-nine cases in the literature are reviewed to delineate the pattern of bleeding in hereditary factor X deficiency.

A new family with classical factor X deficiency as demonstrated by electroimmunoassay

A new family with classical factor X deficiency is described. The proposita is a 6 year old girl who presented with occasional epistaxis and a hematoma after an intramuscular injection. The main laboratory features consisted in a prolongation of partial thromboplastin, prothrombin and Stypven clotting times corrected by the addition of normal serum. Factor X activity varied between 3 and 6%. Factor X amydolytic activity was 15% of normal. Electroimmunoassay failed to show the presence of factor X antigen. No inhibitor was found in the proposita plasma. Parents and other family members showed intermediate levels of factor X activity and antigen and were considered to be heterozygotes. No consanguineity was found in the family.

A family with heterozygous factor X Friuli defect outside Friuli

Three members of the same family were found to have a clotting defect consistent with the diagnosis of heterozygous factor X Friuli disorder. The main features of the defect were a mild prolongation of prothrombin time and partial thromboplastin time, but a normal Stypven-Cephalin clotting time. Factor X activity was 40-50% of normal using tissue thromboplastin, but was perfectly normal using Russell's viper venom and cephalin. Using chromogenic substrate S-2222 the level was 30% of normal. Immunologically, factor X was normal. Bleeding manifestations were mild if any. The hereditary pattern was autosomal. The family comes from an area far away from Friuli and represents the first example of factor X Friuli discovered outside the Friuli.

Hereditary factor VII deficiency in a Chinese family

Hereditary deficiency of factor VII is demonstrated in a Chinese family. The proposita was a 32-year-old female with bleeding diathesis consisting of spontaneous ecchymosis, menorrhagia and recurrent haemarthrosis. The prothrombin time was prolonged and the prothrombin and proconvertin test was 10% of normal. The activated partial thromboplastin time and the Stypven-cephalin clotting time were normal. The prolonged prothrombin time could be corrected by the addition of normal serum, but not by adsorbed normal or coumadin plasma. The factor VII level was 3.6% of normal. One of her brothers had bleeding symptoms and died at age 25, suggesting that factor VII deficiency might have been present. 13 of her family members had partial deficiency of factor VII with plasma levels ranging from 24 to 50%. These results suggest an autosomal recessive inheritance with a homozygous state occurring in the proposita and possibly in her brother, and a heterozygous state occurring in 13 of her family members. Our study marks an extensive survey of factor VII deficiency in an Oriental family.

Post-translational carboxylation of preprothrombin

In summary, in this review on the function of vitamin K in post-translational modification of precursor proteins by carboxylation of certain glutamyl residues, I have tried to cover in particular the recent work on the reaction, the enzymes involved and the mechanisms being considered. In doing this I have also considered vitamin K, its discovery, its functional form and the possible relation of its metabolism to the carboxylation reaction. Equally the various vitamin K-dependent gla-containing proteins currently known have been described. The carboxylation of synthetic small molecule exogenous substrates and the synthesis and metabolism of the products of carboxylation are of great help in studying the reaction. Structural specificity of vitamin K analogs in vivo and in vitro has been compared and the use of various antagonists in vivo and in vitro considered in attempts to gain an understanding of the overall reaction. The reactions subsequent to carboxylation, e.g., the activation of prothrombin to thrombin via serine proteases and the related activation of the other vitamin K-dependent proteins have not been considered in this review. The review has not covered prothrombin or other vitamin K-dependent protein isolation, nor the determination of these proteins. As the vitamin K-dependent protein carboxylation story has developed over the past six years, a number of reviews have been written which help in keeping up with the various aspects of the field as it has expanded. These reviews refer to many of the papers I have had to eliminate due to space limitations. They are referenced as 469-489. The review is in no sense comprehensive and many papers have been missed or only mentioned. I have tried to concentrate on the more recent work and, thus, much of the very fine work of the 1940's on vitamin K chemistry is hardly mentioned. Some redundancy has been built into the organization of the review so that a reader can obtain a reasonable view of any one section without having to search the whole review for all possible relevant information on any particular part of the field.

[Clinical studies of familial hereditary factor VII deficiency (author's transl)]

The discovery of a severe factor VII deficiency with increased bleeding tendency resulted in investigations of 22 members of the family. In the propositus and in two of his siblings a severe hypoproconvertinemia was demonstrated, a partial deficiency was found in ten persons. Studies of the family confirmed that this disorder is transmitted by an autosomal gene with intermediate penetrance. The mutated gene produces a severe deficiency in the homozygote and partial deficiency in the heterozygote. The parents of the homozygote patients were consanguineous. Hemorrhagic diathesis was noted only in patients with a severe factor VII deficiency. Causes for the variability of the clinical manifestations are discussed.

Acquired, transient factor X (Stuart factor) deficiency in patient with mycoplasma pneumonial infection

A case of severe haemorrhagic diathesis due to acquired deficiency of factor X (both immunologically and in procoagulant activity) is presented. The clinical and serological features of this case indicated mycoplasma pneumonial infection. Factor X in the peripheral blood did not appear to be influenced by administration of vitamin K, prothrombin-complex concentrate, fresh plasma or fresh whole blood. Circulating inhibitors of blood coagulation were absent and systemic amyloidosis could not be demonstrated. After 20 d, factor X spontaneously returned to normal. In view of the absence of other known causes of factor X deficiency, a possible relationship with mycoplasma pneumonial infection is suggested.

Major gene analysis of quantitative variation in blood clotting factor X levels

Blood clotting factor ten (X) levels measured in 149 people in six pedigrees were found to fit a mixture of normal distributions. No environmental effect could be identified to account for the wide separation in the means of these distributions. Pedigree analysis reveals that the data are compatible with an autosomal, one locus, two allele genetic model affecting factor X activity. Goodness of fit tests suggest that the allele for low levels of factor X is dominant, though on the basis of likelihood tests, mean heterozygote levels are different from mean homozygote levels. A similar bimodal distribution for factor X levels observed previously in a separate sample of 207 young men, indicated that the proposed dominant allele has an estimated population gene frequency of .53. The earlier estimate is remarkably similar to that obtained with the currently ascertained pedigrees. The postulated major gene accounts for more than half of the variation in factor X levels.

Purification and characterization of an abnormal factor IX (Christmas factor) molecule. Factor IX Chapel Hill

Human Factor IX (Christmas factor) was isolated from the plasma of a patient with mild hemophilia B. The patient's plasma contained 5% Factor IX clotting activity but 100% Factor IX antigenic activity as determined by immunological assays, which included inhibitor neutralization and a radioimmunoassay for Factor IX. This abnormal Factor IX is called Factor IX Chapel Hill (Factor IXCH). Both normal Factor IX and Factor IXCH have tyrosine as the NH2-terminal amino acid. The two proteins have a similar molecular weight, a similar amino acid analysis, the same number of gamma-carboxyglutamic acid residues (10 gamma-carboxyglutamic acid residues), and a similar carbohydrate content. Both exist as a single-chain glycoprotein in plasma. The major difference between normal Factor IX and Factor IXCH is that the latter exhibits delayed activation to Factor IXa in the presence of Factor XIa and Ca2+. Thus, Factor IXCH differs from other previously described abnormal Factor IX molecules.

Factor-VIII activity and antigen, platelet count and biochemical changes after adrenoceptor stimulation

Adrenaline, isoprenaline and salbutamol were administered by intravenous infusion to human subjects. Isoprenaline was covered with practolol in an attempt to reduce the unpleasantness of the circulatory effects. Changes were recorded in pulse rate and blood pressure, and in blood levels of factors V, VIII, X, XI, and XII, platelet count, lactate, pyruvate, potassium and free fatty acids. Factor VIII was studied by clotting assays, by reactions with two rabbit antisera and two human antibodies, and by desulphated agarose chromatography. At the rate at which they were adiminstered, all three drugs increased the pulse rate by 20-40 beats/min. Factor VIII rose c. 2.5 X with adrenaline but only c. 1.5 X with isoprenaline and salbutamol; but other clotting factors did not alter. Chromatography provided no evidence of a change in the size of the molecule carrying factor-VIII clotting activity. The rate of clearance of the heightened plasma activity could not be shown to differ from that of "ordinary" factor VIII infused into haemophiliacs. The platelet count rose after adrenaline, fell after salbutamol and did not change significantly after isoprenaline. Among the biochemical responses, the only significant difference between the drugs was that lactate rose after adrenaline and salbutamol but did not change after isoprenaline. The rise in factor-VIII clotting activity after adrenaline is considered to represent a real increase in blood concentration, presumably by release of additional factor VIII from stores. The evidence suggests that this could be classified as a beta2 effect; and that the quantity which can be released is unrelated to the current plasma level. The rise in platelet count produced by adrenaline may be the resultant of an alpha-mediated rise due to contraction of the exchangeable splenic pool and a beta2-mediated fall, the alpha effect predominating.

Purification and characterization of a coagulant protein from the venom of Russell's viper

The coagulant protein from the venom of Russell's viper was purified by means of successive chromatography on Sephadex G-50, DEAE-cellulose and Sephadex G-200. The purified coagulant protein was homogeneous by polyacrylamide gel electrophoresis and ultracentrifugation. The molecular weight was estimated to be about 100 000 by ultracentrifuge analysis and 130 000 by gel filtration. The coagulant protein contains 11.1% carbohydrate which includes 5.1% hexose (galactose: mannose = 1:1), 5% hexosamine (glucosamine), and 1% neuraminic acid (N-acetylneuraminic acid and N-glycolyneuraminic acid). The isoelectric point is pH 6.3. The results of both sodium dodecyl sulfate electrophoresis and gel filtration in 6 M guanidium chloride suggest that it consists of four polypeptide chains. The coagulant protein functions as an enzyme in activating blood coagulation factor X in the presence of Ca2+. N-a-p-Toluenesulfonyl-L-arginine methyl ester hydrolyzing activity in the preparation definitely decreased during purification and it suggests that the clotting activity is not associated with the esterase activity. The clotting activity is inhibited by diisopropyl phosphorofluoridate and by phenylmethylsulfonyl fluoride, suggesting that the coagulant protein is a serine protease. The optimum pH is between pH 7.0 and pH 8.0. At neutral pH the coagulant protein is stable below 50 degrees C, but is rapidly inactivated above 55 degrees C.

Passovoy factor: A hitherto unrecognised factor necessary for haemostasis

A moderate bleeding diathesis transmitted as an autosomal dominant was found in five members of four generations of the same family. The affected patients had prolonged partial thromboplastin-times and normal levels of all the known clotting-factors. The haemorrhagic diathesis was attributed to a deficiency of a hitherto unrecognised coagulation factor--i.e., the Passovoy facto.

Factor X Friuli: An immunological study in plasma and in serum using several methods

An immunological study of factor X Friuli was carried out using an anti-human-factor X antiserum. The results obtained with different methods were compared. Only an ill-defined factor X band or precipitate was evident on standard immuno-electrophoresis and on immunodiffusion. Using a non-absorbed antiserum a precipitate was evident on eletroimmunoassay, in normal, factor X Friuli and in factor X deficient plasma. On the contary, using an antiserum which had been previously absorbed with factor X deficient plasma, a precipitate was evident only with factor X Friuli plasma or normal plasma. Excellent results were obtained with the cross-over electrophoresis. Using this method a major or factor X band was evident in normal plasma, factor II,P FACTOR VII, factor IX deficient plasmas and in the factor X FRIULI PLASMA. No factor X band was evident in factor X deficient plasmas and in absorbed normal plasma. Lighter, more cathodic bands were seen in all plasmas. These were due to secondary activities of the antiserum and could be disregarded. Friuli serum factor X and normal serum factor X showed a slightly more anodic migration as compared to their plasma counterparts. In coumarin plasma two factor X bands were evident; one normal in position and one slightly more catholidic. In the bidimensional immunoelectrophoresis two precipitates are visible in normal plasma and in factor X Friuli plasma. In factor X deficient plasma only one precipitate is evident. This latter precipitate is due to the secondary activity of the antiserum used. On the basis of these data it is concluded that factor X Friuli behaves, immunologically, as normal factor X.