Factor XI activity and factor XI antigen in homozygous and heterozygous factor XI deficiency

A relatively potent antiserum against highly purified, unactivated human factor XI antigen was raised in a rabbit. This antiserum, after concentration, neutralized 50% of the factor XI clotting activity of a standard normal plasma at an antiserum dilution of 1/900. The antiserum was used in a neutralization-inhibition assay to study the relation between factor XI clotting activity and factor XI antigen in plasma from ten unrelated patients with homozygous factor XI deficiency and from 12 heterozygous family members of these patients. No evidence of factor XI antigen significantly in excess of factor XI activity was found in either group. All data to date have been consistent with the hypothesis that hereditary factor XI deficiency represents a genetic disorder resulting from the absence of factor XI molecule. Severity of bleeding in factor XI deficiency could not be correlated with the level of factor XI activity or factor XI antigen.     

A molecular genetic study of factor XI deficiency

Factor XI deficiency is a rare bleeding diathesis found predominantly in Ashkenazi Jewish kindreds. A recent study of six Jewish patients identified three distinct mutations (Types I, II, and III) in the factor XI gene that were sufficient to fully define the genotypes of the patients. We have investigated 63 patients with factor XI deficiency and find overall allele frequencies of 44% for the type II mutation, 31% for the type III mutation, and 0% for the type I mutation. Therefore, 25% of the mutant factor XI alleles in our sample remain undefined. However, the distribution of mutant alleles is significantly different between Jewish and non-Jewish populations with hitherto undefined mutations accounting for 84% of the disease alleles in non-Jewish patients. Plasma factor XI:C levels were found to differ significantly between different homozygous and compound heterozygous genotypes and the inheritance of the II/III genotype was found to carry an increased risk of the most severe bleeding tendency.     

A novel factor XI gene mutation associated with mild factor XI deficiency in a symptomatic patient.

Congenital factor XI deficiency is a rare condition, in which plasma factor XI levels correlate poorly with the severity of haemorrhage. The condition is typically characterized by post-traumatic bleeding. The factor XI gene is located on chromosome 4 and contains 15 exons. More than 80 mutations have so far been described. We describe a novel mutation in the factor XI gene associated with mild factor XI deficiency. The patient, who is of Irish descent, has a history of post-traumatic bleeding and was found to have a borderline factor XI deficiency. DNA sequence analysis of the factor XI gene revealed a novel T to A mutation at nucleotide 168 resulting in the substitution of the cysteine residue at codon 38 with a stop codon (Cys38STOP). The mutation predicts the premature termination of translation of factor XI mRNA resulting in a truncated, and probably unstable, factor XI protein. The presence of the mutation is consistent with the patient's borderline factor XI deficiency.     

Thromboembolic phenomena in patients with hereditary factor XI deficiency

Factor XI deficiency is an hereditary coagulopathy that is usually associated with milder tendency to bleeding with comparison to hemophilia A. While the failure of stable fibrin clot formation may lead to bleeding, it is speculated that the same process may provide a protection against thrombosis of injured arteries due to atherosclerotic plaque rupture. Whereas 2 studies indicate that hemophiliacs have decreased mortality rate from cardiovascular diseases, there is no similar data regarding factor XI deficiency patients. In here we report about 3 patients with severe factor XI deficiency who have a long-standing history of thromboembolic phenomena: 2 patients with myocardial infarctions, and one patient with transient ischemic attacks. We discuss the possible role of factor XI in thrombosis, and whether its deficiency may protect patients from thromboembolic phenomena.     

Inheritance and bleeding in factor XI deficiency

A study of 20 Jewish and four non-Jewish kindreds transmitting factor XI deficiency (164 individuals) confirmed inheritance to be autosomal with severe deficiency in homozygotes (mean factor XI level 3.8 u/dl, SD 2.91) and partial deficiency in heterozygotes (mean factor XI level 57 u/dl, SD 10.42; normal mean factor XI level 96 u/dl, SD 11.6). The probability of an individual being heterozygous can be predicted from the factor XI level using a graph derived from this data. The accuracy is increased by including the prior probability derived from the pedigree. A high frequency of heterozygote to heterozygote mating was observed in the Jewish families consistent with an estimated gene frequency of 13.4% in this racial group. The relationship between factor XI level and bleeding tendency is poor; a third of heterozygotes had bled excessively after surgery, including six with factor XI levels above 50 u/dl, showing this condition to have clear signs of expression in heterozygotes. The lower limit of the normal range (2 SDs from the mean) was found to be 72 u/dl.     

Clinical experience of factor XI deficiency: the role of fresh frozen plasma and factor XI concentrate

Summary. Factor XI deficiency is a rare autosomally transmitted coagulopathy that is associated with a variable bleeding tendency. Recently there have been reports of thrombotic events following the administration of a virally inactivated factor XI concentrate (BPL) to factor XI deficient patients. We have therefore reviewed a single centre's experience of the use of factor XI concentrate over a 6-year period and compared this to our previous experience of either no treatment or treatment with fresh frozen plasma (FFP) in 103 patients.
There were 156 procedures performed without haemo- static cover. The incidence of bleeding was greatest following tonsillectomy (71%) and dental extraction (Sl'h). There was a trend for bleeding complications to be associated with lower levels of factor XI but patients with all levels of factor XI suffered bleeding complica- tions. There were 38 procedures carried out under FFP cover, with only one patient suffering excessive bleeding and no serious complications.
Factor XI concentrate was given to 25 patients to cover 45 episodes. There were no bleeding complications. Three patients suffered serious complications. One patient, with a previous history of cardiovascular disease, died of a myocardial infarction and a second had an ischaemic episode resulting in a %day hospital admission. These episodes both occurred on the same day as the factor XI infusion. A third patient suffered bilateral pulmonary emboli 7 weeks after a prolonged course of factor XI concentrate.
These finding suggest that factor XI concentrate should be contraindicated in patients with a history of cardiovascular disease, when FFP should be used. Guide- lines for the use of factor XI concentrates should be revised, and work performed to establish the mechanism of these thrombotic events.     

Prevalence,causes, and characterization of factor XI inhibitors in patients with inherited factor XI deficiency

Factor XI deficiency, an injury-related bleeding disorder, is rare worldwide but common in Jews in whom 2 mutations, Glu117Stop (type II) and Phe283Leu (type III), prevail. Mean factor XI activities in homozygotes for Glu117Stop and for Phe283Leu are 1 and 10 U/dL, respectively. Inhibitors to factor XI in patients with severe factor XI deficiency have been reported in a small number of instances. This study was undertaken to determine the prevalence of acquired inhibitors against factor XI in patients with severe factor XI deficiency, discern whether these inhibitors are related to specific mutations, and characterize their activity. Clinical information was obtained from unrelated patients with severe factor XI deficiency, and blood was analyzed for factor XI activity, inhibitor to factor XI, and causative mutations. Immunoglobulin G purified from patients with an inhibitory activity was tested for binding to factor XI, effects on activation of factor XI by factor XIIa and thrombin, and activation of factor IX by exogenous factor XIa. Of 118 Israeli patients, 7 had an inhibitor; all belonged to a subgroup of 21 homozygotes for Glu117Stop who had a history of plasma replacement therapy. Three additional patients with inhibitors from the United Kingdom and the United States also had this genotype and were exposed to plasma. The inhibitors affected factor XI activation by thrombin or factor XIIa, and activation of factor IX by factor XIa. The results imply that patients with a very low factor XI level are susceptible to development of an inhibitor following plasma replacement.     

The management of factor XI deficiency

Summary. Factor XI deficiency leads to a more variable bleeding tendency than haemophilia A or B. Although severely deficient individuals are likely to bleed excessively especially after surgery in areas of the body with increased fibrinolysis, there is evidence that some partially deficient individuals are at risk of excessive bleeding. This will entail careful planning for surgery. Several therapeutic modalities are available which include fresh frozen plasma, factor XI concentrates, fibrin glue, antifibrinolytic drugs and desmopressin. The advantages and risks of these are considered. Factor XI concentrate may be indicated for procedures with a significant risk of bleeding especially in younger patients with severe deficiency, but its use in older patients has been associated with thrombotic phenomena. If fresh frozen plasma is to be used, it is preferable to obtain one of the virally inactivated products. Fibrin glue is a useful treatment which deserves further study.     

Factor XI deficiency and its management

Factor XI deficiency has a more variable bleeding tendency than haemophilia A or B. Individuals with severe deficiency have only a mild bleeding tendency, which is typically provoked by surgery, but the risk of bleeding is not restricted to individuals with severe deficiency. The bleeding tendency varies between individuals with similar factor XI levels, and sometimes the bleeding tendency of an individual may vary. The reasons for this are not fully understood, although in cases of severe deficiency there is some correlation between phenotype and genotype.
Factor XI is activated by thrombin. The role of factor XI in physiological processes has become clearer since this fact was discovered, and the discovery has contributed to a revised model of blood coagulation. Factor XI deficiency occurs in all racial groups, but is particularly common in Ashkenazi Jews. The factor XI gene is 23 kilobases long. Two mutations are responsible for most factor XI deficiency in the Ashkenazi population, but a number of other mutations have now been reported in other racial groups.
Individuals with factor XI deficiency may need specific therapy for surgery, accidents, and dental extractions. Several therapies are available which include fresh frozen plasma, factor XI concentrates, fibrin glue, antifibrinolytic drugs, and desmopressin. Each has advantages and risks to be considered. Factor XI concentrate may be indicated for procedures with a significant risk of bleeding especially in younger patients with severe deficiency, but its use in older patients has been associated with thrombotic phenomena. If fresh frozen plasma is to be used it is preferable to obtain one of the virally inactivated products. Fibrin glue is a useful treatment which deserves further study.     

An Alu-mediated 31.5-kb deletion as the cause of factor XI deficiency in 2 unrelated patients

Factor XI deficiency (MIM 264900) is an autosomal bleeding disorder of variable severity. Inheritance is not completely recessive as heterozygotes may display a distinct, if mild, bleeding tendency. Recent studies have shown the causative mutations of factor XI deficiency, outside the Ashkenazi Jewish population, to be highly heterogeneous. We studied 39 consecutively referred patients with factor XI deficiency to identify the molecular defect. Conventional mutation screening failed to identify a causative mutation in 4 of the 39 patients. Epstein-Barr virus (EBV)-transformed cells from these 4 patients were converted from a diploid to haploid chromosome complement. Subsequent analysis showed that 2 of the patients had a large deletion, which was masked in the heterozygous state by the presence of a normal allele. We report here the first confirmed whole gene deletion as the causative mutation of factor XI deficiency, the result of unequal homologous recombination between flanking Alu repeat sequences.     

A novel congenital haemostatic defect: combined factor VII and factor XI deficiency.

Isolated deficiencies of factors VII and XI are both rare. Not surprisingly, therefore, combined factor VII and XI deficiency has not been reported previously. We report here a kindred with a combined heterozygous deficiency for both factors VII and XI. The proposita is a 28-year-old woman who had both a prolonged prothrombin time (PT) and a prolonged activated partial prothrombin time (APTT) associated with a mild bleeding tendency. Coagulation studies were performed on the six available members of this kindred. The PT and APTT were normal or mildly abnormal in five of these individuals. Factor VII coagulant activity (VII:C) varied from 0.33 to 0.77 units/ml in affected subjects. In contrast, the concentration of factor VII-related antigen for the six individuals ranged from 0.68 to 2.10 units/ml. Comparable factor VII:C levels were obtained when each subject's plasma was tested with either a rabbit or a human thromboplastin reagent. Factor XI coagulant activity was less than 0.5 units/ml in three of the six subjects and normal (approximately 1.0 units/ml) in the other three. The concentrations of thrombin-antithrombin-III and prothrombin fragment 1.2 were within normal limits for all individuals. In addition to being associated with heterozygous factor XI deficiency, the abnormal factor VII molecule in the plasma of affected individuals in this kindred appears to represent a newly described mutation. This is suggested by the pattern of reactivity with thromboplastin from different species, the normal tissue factor binding and the bleeding tendency in heterozygous individuals in this kindred.     

Plasma replacement therapy during labor is not mandatory for women with severe factor XI deficiency.

Severe factor XI deficiency is an injury-related bleeding disorder. The risk of excessive post-partum hemorrhage in affected women has so far been evaluated in a relatively small number of patients and it is uncertain whether prophylactic treatment with fresh frozen plasma or factor XI concentrate is needed during or after vaginal or cesarean delivery. We retrospectively analyzed bleeding manifestations related to vaginal and/or cesarean deliveries in a cohort of 62 women with factor XI activity < 17 U/dl and evaluated whether replacement therapy is essential. Fifty-one women had 139 vaginal deliveries, six women had 13 cesarean deliveries, and five women had seven vaginal as well as five cesarean deliveries. Forty-three of the 62 women (69.4%) never experienced post-partum hemorrhage during 93 deliveries (85 vaginal, eight cesarean). Hemorrhage occurred in 19 women, which in six women accompanied each one of their 17 vaginal deliveries. Post-partum hemorrhage had no relationship with the abnormal genotype that caused factor XI deficiency nor with factor XI level. These observations suggest that the use of fresh frozen plasma or factor XI concentrate during and/or after vaginal delivery is not mandatory in women with severe factor XI deficiency and can be reserved for patients who develop excessive hemorrhage. For women requiring cesarean section it appears that the same policy can be advocated but more observations are needed.     

Percutaneous coronary intervention in a patient with congenital factor XI deficiency and acquired inhibitor

BACKGROUND: Factor XI deficiency has been associated with bleeding diathesis mostly secondary to trauma and post-operatively depending on the severity of deficiency. Cases with factor XI deficiency having undergone cardiac surgery and coronary intervention after appropriate replacement therapy have been reported in the past. The presence of inhibitor in factor XI deficiency poses a hematological challenge and literature regarding coronary intervention in such patients is limited. Immunosuppressive therapy, plasma exchange and factor VII product transfusions have been used prior to cardiac interventions in few such reported cases. METHOD: We report our approach in such a case of Percutaneous Transluminal Coronary Angioplasty in a 72-year-old male of Jewish origin who has congenital factor XI deficiency complicated with acquired inhibitor. RESULTS: In some cases, the acuity of the coronary syndrome may mandate immediate coronary intervention. However, patient's history of factor XI deficiency and acquired inhibitor pose a major dilemma of further course of action. We performed percutaneous balloon angioplasty in this case with no anti-coagulant and with favorable outcome. CONCLUSION: Under these circumstances of significant coagulation disorder and based on the case report, we recommend that balloon angioplasty be undertaken with no additional anti-coagulation other than Aspirin.     

Dental surgery in patients with severe factor XI deficiency without plasma replacement.

Bleeding following dental extraction is frequently the first manifestation of severe factor XI deficiency. Safe oral surgery has previously been performed in such patients by using plasma replacement therapy with or without concomitant administration of antifibrinolytic agents. The aim of this study was to determine whether such patients can undergo safe dental extractions using only an antifibrinolytic agent. The study group consisted of 19 patients with severe factor XI deficiency (factor XI:C level less than 14 U/dl) who had previously bled following dental extractions (14 patients) or other trauma (five patients). Tranexamic acid, 1 g q.i.d., was given from 12 h before surgery, until 7 days afterwards. No excessive bleeding was observed following dental extractions. One patient had slight oozing after 3 days which ceased spontaneously. Thus, plasma replacement no longer appears necessary for patients with severe factor XI deficiency requiring dental extractions.     

Inherited factor XI deficiency: a concise review

Inherited factor XI (FXI) deficiency, also called Hemophilia C, is an uncommon autosomal recessive disorder, which is associated with a variable bleeding tendency that usually manifests after trauma or surgery. This concise report reviews current knowledge regarding the pathogenesis, genetics, diagnosis, clinical manifestations and management of this inherited bleeding disorder.     

Inherited factor XI deficiency: A concise review

Inherited factor XI (FXI) deficiency, also called Hemophilia C, is an uncommon autosomal recessive disorder, which is associated with a variable bleeding tendency that usually manifests after trauma or surgery. This concise report reviews current knowledge regarding the pathogenesis, genetics, diagnosis, clinical manifestations and management of this inherited bleeding disorder.     

Congenital factor VII deficiency

Summary Four new cases with congenital homozygous factor VII deficiency are described. Factor VII levels were reduced to <1%,3%,8% and 10%, respectively. The incidence and severity of bleeding symptoms were well correlated with the measured factor VII activity. In the severe case of factor VII deficiency (<1%) a home treatment program was started because of severe recurrent hemarthroses. This entailed transfusions of 20 U/kg body weight prothrombin complex or factor VII concentrate in case of acute bleeding approximately every three weeks. These transfusions have been carried out successfully without any problems. In contradiction, two brothers with hypoproconvertinemia (factor VII 8% and 10%, respectively) reached an age of more than 70 years. Despite replacement therapy postoperative bleeding followed one appendectomy, whereas no postoperative bleeding followed patients requiring Achilles tendon lengthening and an above knee amputation and only slight bleeding followed a tonsillectomy. Based on our experience we suggest that in patients with factor VII deficiency of less than 10%, when undergoing surgery, should be maintained a minimal factor VII activity of 10–15% during the first three postoperative days.     

Treatment of massive cecal bleeding in a 28-Year-old patient with homozygous factor V deficiency with activated factor VII

Factor V deficiency is usually accompanied with recurrent epistaxis, menorrhagia and haemorrhages after trauma. So far, gastrointestinal bleeding has not been reported. We describe here the first case of severe cecal bleeding in a 28-year-old woman with homozygous factor V deficiency. As a reasonable alternative to large amounts of fresh frozen plasma, we indicated recombinant activated factor VII (rFVIIa), as supra-physiological concentrations directly activate factor X and prothrombin on the surface of activated platelets. With this regimen, the bleeding immediately stopped and the patient was discharged three days later. Rotation thromboelastometry studies showed a marked improvement in clot generation after rFVIIa infusion. We conclude that massive cecal mucosal bleeding is a possible manifestation of homozygous factor V deficiency and rFVIIa could be a successful therapy.     

Studies on a circulating anticoagulant inhibiting factor XI in a patient with congenital deficiency and carcinoma of the prostate

An inhibitor of plasma thromboplastin antecedent (PTA, factor XI), measured in coagulant and radioimmunoassays, was detected in a 60-year-old man with carcinoma of the prostate who had no evidence of a bleeding tendency. Family studies indicated that the patient was either a homozygote or a heterozygote for hereditary factor XI deficiency. In contrast to earlier described patients with factor XI deficiency in whom inhibitors were detected, the patient was unaware of having been transfused with blood or blood products at any time before the discovery of the inhibitor. The inhibitor of factor XI in the patient's plasma appeared to be predominantly in the IgG4 fraction and to be directed at a locus on the factor XI molecule other than the active site; it did not block the amidolytic properties of activated factor XI (XIa). Rather, it appeared to block adsorption of factor XI to negatively charged surfaces. The inhibitor interfered with measurement of other components of the intrinsic pathway of thrombin formation, perhaps explaining the low titres of other coagulation factors of the intrinsic system reported in patients with strong inhibitors directed against factor XI.