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PubMed1987

Identification of a defective factor XI cross-reacting material in a factor XI-deficient patient.

A homozygous factor XI-deficient girl, who appeared to be positive for cross-reacting material (CRM+) was studied for clarification. Factor XI antigen (F XI:Ag) was measured by radial immunodiffusion using monospecific, heterologous anti-factor XI antibodies. Factor XI coagulant activity (F XI:C) was determined in a modified activated partial thromboplastin time (APTT) test. The ratio of F XI:C to F XI:Ag was 0.04 for the proposita, as compared with 0.7 to 0.74 in the other family members. In contrast, 12 normal individuals had ratios of F XI:C to F XI:Ag of 1.04 +/- 0.15. F XI esterolytic activity was clearly higher than F XI:C in the proband, but not in her relatives. Immunoblotting studies demonstrated F XI CRM in the patient's plasma. Chromatography on diethylaminoethanol (DEAE)-Sephadex at pH 8.4 led to an almost complete removal of F XI from the plasma. The defective F XI was not bound to a negatively charged kaolin surface due to an abnormal interaction with high-mol-wt kininogen (HMWK).

Antigens↗
PubMed1985

Comparison of bleeding tendency, factor XI coagulant activity, and factor XI antigen in 25 factor XI-deficient kindreds.

The relationship of clinical bleeding tendency and factor XI antigen (XI:Ag) in factor XI deficiency was studied in 78 members of 25 factor XI-deficient kindreds. Factor XI:Ag was measured in a competitive radioimmunoassay, using monospecific, heterologous anti-factor XI antibody. 125I-labeled factor XI, and staphylococcal protein A as the precipitating agent. Deficiency of factor XI clotting activity (XI:C), less than 0.62 U/mL, occurred in 48 individuals, 22 of whom experienced postoperative or posttraumatic bleeding: Their mean factor XI:C was 0.21 +/- 0.04 U/mL (SEM), and factor XI:Ag was 0.23 +/- 0.04 U/mL. The remaining 26 had no clinical bleeding, many despite surgical challenge: Their mean factor XI:C was 0.30 +/- 0.04 U/mL, and factor XI:Ag was 0.34 +/- 0.05 U/mL. In all, 13 kindreds had between 1 and 11 members with bleeding; the other 12 had none with deficient hemostasis. Two heterozygous factor XI-deficient individuals appeared to be positive for cross-reacting material (CRM+). The slope of the regression line for factor XI:C and factor XI:Ag data points in the 78 individuals tested did not differ from control, and all points fell within 95% confidence limits derived from control. In conclusion, bleeding tendency appears to be consistent within a given kindred and is not determined exclusively by factor XI:C or factor XI:Ag levels.

Antigens↗
PubMed1995

Definition of the bleeding tendency in factor XI-deficient kindreds--a clinical and laboratory study.

Individuals with severe factor XI deficiency are prone to excessive bleeding after injury or surgery, but the existence of a haemorrhagic tendency in partial factor XI deficiency is controversial. In this study, 172 members of 30 kindreds (20 non-Jewish) transmitting factor XI deficiency in North West England were interviewed and a bleeding history questionnaire completed. Blood was taken for coagulation assays. The questionnaires were categorised independently by two assessors to determine presence or absence of a bleeding tendency, in the absence of information about the factor XI level or family history. Analysis shows that 48% of heterozygotes have a bleeding tendency. Eighteen (60%) families came to attention because of bleeding problems in heterozygotes. Comparison of histories between partially deficient and non-deficient individuals demonstrated a higher incidence of menstrual problems, an increase in significant bruising, and an increased likelihood of excessive bleeding after tonsillectomy and dental extractions. The incidence of von Willebrand's disease was not increased, but individuals with heterozygous factor XI deficiency who were bleeders tended to have lower levels of factor VIIIc and von Willebrand factor, and were more commonly of blood group 0. These features may contribute to the bleeding tendency. There was no evidence of alteration in factor VII activity (as defined by the ratio of activity to antigen) between the bleeders and non-bleeders. This is convincing evidence for abnormal bleeding in factor XI deficiency which is not confined to severely deficient patients.

Adolescent↗
PubMed1982

An alternative extrinsic pathway of human blood coagulation.

To study the interrelationships of the major human coagulation pathways, factor X activation in normal and various deficient human plasmas was evaluated when clotting was triggered by dilute rabbit or human thromboplastin. Various dilutions of thromboplastin were added to plasma samples containing 3H-labeled factor X, and the time course of factor X activation was determined. At a 1/250 dilution of rabbit brain thromboplastin the rate of factor X activation in factor VIII or factor IX deficient plasma was only 10% of the activation rate seen for normal or factor XI deficient plasma. Reconstitution of the deficient plasmas with factors VIII or IX, respectively, restored normal factor X activation. Similar results were obtained when various dilutions of human thromboplastin replaced the rabbit thromboplastin. From these experiments, it is inferred that normal activation of factor X in plasma due to dilute thromboplastin requires factors VII, IX and VIII. An alternative extrinsic pathway that involves factors VII, IX, and VIII may be a major physiologic extrinsic pathway, and this pathway may help to explain the clinical observations of bleeding diatheses in patients deficient in factors IX or VIII.

Animals↗
PubMed1984

Fibrin formation, fibrinopeptide A release, and platelet thrombus dimensions on subendothelium exposed to flowing native blood: greater in factor XII and XI than in factor VIII and IX deficiency.

Fibrin deposition and platelet thrombus dimensions on subendothelium were studied in four groups of patients with coagulation factor deficiencies. Five patients with factor VIII deficiency (APTT 120 +/- 8 sec) and three patients with factor IX deficiency (APTT 125 +/- 11 sec) were severe bleeders, whereas four patients with factor XII deficiency and seven with factor XI deficiency were either asymptomatic or only mild bleeders despite APTT values of 439 +/- 49 and 153 +/- 13 sec, respectively. Everted segments of deendothelialized rabbit aorta were exposed at a shear rate of 650 sec(-1) for 5 and 10 min to directly sampled venous blood in an annular chamber. Blood coagulation was evaluated by measuring fibrin deposition (percent surface coverage) on the subendothelium and post-chamber fibrinopeptide A levels; platelet thrombus dimensions on the subendothelium were evaluated by determining the total thrombus volume per surface area (using an optical scanning technique) and the average height of the three tallest thrombi. Consistent differences were observed among the patient groups for both the 5-min and 10-min exposure times. The larger of the 5- and 10-min exposure-time values was used to calculate group averages. Fibrin deposition in normal subjects was 81% +/- 5% surface coverage, and post-chamber fibrinopeptide A values were 712 +/- 64 ng/ml. Markedly decreased fibrin deposition and fibrinopeptide A levels were observed in factor VIII deficiency (2% +/- 1% and 102 +/- 19 ng/ml) and factor IX deficiency (11% +/- 7% and 69 +/- 11 ng/ml). In contrast, significantly higher values were obtained in patients deficient in factor XI (33% +/- 5% and 201 +/- 57 ng/ml) and factor XII (66% +/- 12% and 306 +/- 72 ng/ml). Differences in thrombus dimensions were also observed. In normal subjects, the value for thrombus volume and average height of the tallest thrombi were 8.3 +/- 1.3 cu micron/sq micron and 145 +/- 11 micron, respectively, and in patients were as follows: FVIII, 2.7 +/- 0.6 and 71 +/- 7; FIX, 4.5 +/- 1.8 and 88 +/- 14; FXI, 11.8 +/- 1.9 and 125 +/- 10; and FXII, 7.9 +/- 3.1 and 130 +/- 25. Platelet thrombus dimensions were normal in a patient with fibrinogen deficiency, indicating that the smaller thrombi in factor VIII and factor IX deficiencies were probably due to impaired evolution of thrombin rather than diminished fibrin formation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

Expression of human blood coagulation factor XI: characterization of the defect in factor XI type III deficiency.

Human factor XI (FXI) is a blood coagulation factor participating in the early phase of the intrinsic pathway of blood coagulation. It circulates in blood as a glycoprotein composed of two identical chains held together by a single disulfide bond between the fourth apple domains. FXI has been expressed in baby hamster kidney (BHK) cells, where it was synthesized as a single-chain molecule that was converted to the dimer before secretion. The recombinant protein was fully active in a clotting assay, indicating that it interacted readily with other components of the coagulation cascade. A mutant FXI in which Phe283 was converted to Leu (Phe283Leu) was also expressed in BHK cells. This amino acid change occurs in the fourth apple domain of FXI and corresponds to the type III deficiency in Ashkenazi Jews. The mutant protein was secreted at reduced levels (about 8%) compared with normal FXI. This was due to a defect in the dimerization of the molecule rather than a decrease in the transcription of type III messenger RNA. Once secreted, however, the mutant protein consisted of a dimer with full biologic activity. The in vitro expression of FXI indicated that the impaired dimerization and secretion of the Phe283Leu mutant can account for the defect found in patients who are homozygous for the type III FXI deficiency.

Amino Acid Sequence↗
PubMed1987

Acquired factor XI inhibitors in congenitally deficient patients.

Four factor XI (F XI)-deficient patients are described, all of whom formed circulating anticoagulants against F X1. In the three most severely affected patients (F XI 0%-6% activity), the anticoagulant appeared to have been stimulated by plasma infusion. However, in the milder case (25% F XI activity), no infusion had been documented. The findings in these cases emphasize the diversity of F XI inhibitors in congenitally deficient patients. Awareness of the potential development of these inhibitors will be helpful in both daily management and perioperative care of such patients.

Adult↗
PubMedDate not supplied

Combined factor VIII and factor XI congenital deficiency: a case report.

Combined congenital defect involving both Factor VIII and XI is a very rare disorder. We describe a case of combined Factor VIII and XI deficiency in which the propositus has a mild hemophilia A and inherited a Factor XI deficiency from the father. Moreover, we report on the benefit of DDAVP administration to the patient during a bleeding episode.

Adult↗
PubMed2005

Preoperative screening for coagulopathy using prothrombin time and partial thromboplastin time in patients requiring primary cranial vault remodeling.

BACKGROUND: The aim of this study was to investigate the prevalence of abnormal preoperative screening prothrombin time and partial thromboplastin time in patients listed for primary cranial vault remodeling that required hematologic workup and their diagnoses and subsequent management. METHODS: This retrospective analysis was performed from January of 2000 to December of 2003 at the International Craniofacial Institute, Dallas, Texas, on a total of 168 patients. RESULTS: All patients had a normal prothrombin time. Abnormally raised partial thromboplastin time was found in six patients (prevalence of 3.57 percent), one who had factor XI deficiency, one who had a borderline factor XI deficiency and circulating inhibitor, one who had an intermittent factor XI deficiency and circulating inhibitor, one who had a borderline von Willebrand's disease with low factor XII, and the remaining two who had a circulating inhibitor of coagulation. Of these six patients, the perioperative management was altered in four of five patients, and one patient declined surgery out of fear of surgical morbidity. The surgery of one patient was aborted intraoperatively because of abnormal bleeding without clot formation after the calvarial burr holes had been drilled. The mean blood loss was 183 ml for the four patients with completed surgery and 100 ml for one patient. CONCLUSIONS: The authors conclude that even though the prevalence of abnormal screening partial thromboplastin time in these patients was low (3.57 percent), detection of an abnormal result required preoperative correction of coagulopathy in 80 percent of cases.

Blood Coagulation Disorders↗
PubMed2000

Management of factor XI inhibitor for cardiac intervention: successful treatment with immunosuppressive therapy and plasma exchange.

Two cases with congenital homozygous factor XI deficiency developed a factor XI inhibitor following repeated plasma transfusions. Case 1 was given cyclophosphamide, intravenous immunoglobulin, and steroids. The factor XI inhibitor disappeared on day 103 and cardiac catheterization was performed without complications after giving fresh frozen plasma. Case 2 was effectively managed by plasma exchange for cardiac catheterization and surgery. However, after five plasma exchange procedures, the same plasma volume exchange was not effective in shortening the activated partial thromboplastin time (APTT). A significant heparin rebound occurred 4 h after heparin neutralization with protamine sulphate for which the patient needed to have a blood clot evacuated from around the heart.

Aged↗
PubMed1976

Combined deficiencies of Factor VIII (AHF) and Factor XI (PTA).

Combined deficiencies of Factor VIII and Factor XI associated with moderate degree of bleeding symptoms were found in 3 brothers. Examination of Factor VIII activity and Factor VIII-related antigen revealed that the Factor VIII activity/Factor VIII-related antigen ratio was significantly decreased in their mother and maternal grandmother consistent with the carrier state of hemophilia. Factor XI deficiency was found in 2 siblings, the father, and 2 of his sisters. The paternal grandmother was thought to carry the abnormal Factor X I gene, although her Factor XI level was normal, because of a significant bleeding history. It was concluded that the combined Factor VIII and XI deficiencies in the 3 brothers represent the coincidental inheritance of 2 separate and independent abnormal genes.

Adolescent↗
PubMed1978

Factor XI (PTA) deficiency in an English-American kindred.

2 sisters of English-American descent had a mild bleeding syndrome due to marked deficiency (less than 1% activity) of factor XI. This defect was transmitted in an autosomal recessive manner. Although factor XI deficiency was previously thought to occur largely, if not exclusively in Jews, extensive review of geneologic records and analysis of family names failed to disclose Jewish ancestry. These findings, together with the existence of several definite and presumed consanguineous English-American ancestors, the fact that family members had resided in a restricted geographic area for many generations, and analysis of English and Jewish immigration patterns lead to the conclusion that this defect is not likely to be of Jewish derivation. Should this mutation have occurred in the distant past it is conceivable that the gene pool for this defect is substantial, particularly in certain areas in New England.

Consanguinity↗
PubMed2005

United States' factor XI-deficiency patients need a safer treatment.

A replacement factor for Factor XI with is virally inactivated is not available in the U.S. Elsewhere an inactivated concentrate has been used. A review of the experience over 15 years suggests that this product is safe and effective and suggests its potential use in the U.S. The most serious complication of the factor was a slight increase in DIC and thrombotic events.

Blood Component Removal↗
PubMed1994

Advances and dilemmas in factor XI.

Factor XI is a key component of the intrinsic pathway of blood coagulation in vitro. The poor correlation between the clinical bleeding diathesis in factor XI deficiency and abnormalities in clotting assays that measure intrinsic coagulation brings into question the role of this serine protease in in vivo hemostasis. The characterizations of the point mutations responsible for the majority of cases of severe factor XI deficiency in Ashkenazi Jews and subsequent epidemiologic studies have provided insight into the perplexing hemostatic abnormalities in this disorder. It appears that excessive bleeding in factor XI deficiency depends on the severity of the deficiency in certain situations and on the location of the hemostatic challenge in others. Additional coexisting abnormalities of hemostasis, such as von Willebrand's disease, may also be responsible for variation in clinical presentation, particularly in those individuals with mild factor XI deficiency. The absence of abnormal bleeding in congenital deficiency of factor XII, the protease that activates factor XI in the intrinsic cascade, has stimulated a search for other mechanisms for factor XI activation. Recent studies have pointed to the serine protease thrombin and autoactivation by activated factor XI as possible alternatives to factor XII as activators of factor XI. These findings suggest that factor XI, rather than operating in a pathway for the initiation of hemostasis, may function in the consolidation of clot formation after the initiation of the hemostatic process by other mechanisms.

Amino Acid Sequence↗
PubMed2003

Hematological findings in Noonan syndrome.

OBJECTIVE: Noonan syndrome is a multiple congenital anomaly syndrome, and bleeding diathesis is considered part of the clinical findings. The purpose of this study was to determine the frequency of hemostatic abnormalities in a group of Noonan syndrome patients. METHOD: We studied 30 patients with clinical diagnosis of Noonan syndrome regarding their hemostatic status consisting of bleeding time, prothrombin time, activated partial thromboplastin time and thrombin time tests, a platelet count, and a quantitative determination of factor XI. RESULTS: An abnormal laboratory result was observed in 9 patients (30%). Although coagulation-factor deficiencies, especially factor XI deficiency, were the most common hematological findings, we also observed abnormalities of platelet count and function in our screening. CONCLUSIONS: Hemostatic abnormalities are found with some frequency in Noonan syndrome patients (30% in our sample). Therefore, we emphasize the importance of a more extensive hematological investigation in these patients, especially prior to an invasive procedure, which is required with some frequency in this disorder.

Adolescent↗