Hereditary plasma thromboplastin antecedent (PTA, FXI) deficiency in a Saudi family

A rare case of factor XI (PTA) deficiency was discovered in a Saudi family in the Riyadh area. Nine members of the family were studied. Two were found to have a severe PTA deficiency; levels of factor XI clotting activity were 0.01 i.u./ml and 0.02 i.u./ml respectively. Both plasmas were markedly deficient in factor XI antigen and appeared to be negative for cross-reactive material (CRM-). The parents were first cousins and both were found to have a minor PTA deficiency. Factor XI levels were: mother 0.048 i.u./ml and father 0.33 i.u./ml. Another sibling was found to have a FXI level of 0.47 i.u./ml. Menorrhagia and bleeding for 1 day after tooth extraction were the main bleeding manifestations found in one member with severe PTA deficiency. Clinically this member presented with iron deficiency anaemia. Other family members had no significant history of bleeding tendency. This is the first report of a Saudi Arabian family with PTA deficiency.     

Factor XI deficiency in an Arab Moslem family in Israel

An arab moslem family with members affected by PTA deficiency is described. 3 children were found to have major deficiency, factor XI procoagulant activity being 3, 3 and 4 units/dl. 8 members, including parents, paternal grandparents and 4 siblings, were found to have minor deficiency of factor XI (40 to 68 units/dl). Assays of immunoreactive material in 4 members corresponded to the level of procoagulant activity. In this family, gene expression is autosomal recessive. The only bleeding episode reported was haematuria in the propositus. No other spontaneous, post-trauma or post-operative bleeding was noted. The PTA deficiency was reported until now, mainly in ashkenazi jews. This family is the first case of PTA deficiency ever reported in arab moslems.     

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.     

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.     

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.     

The Mode of Inheritance of PTA Deficiency: Evidence for the Existence of Major PTA Deficiency and Minor PTA Deficiency

Plasma thromboplastin antecedent (PTA) activity was measured with aquantitative assay in the available members of the families of eight propositiwith severe PTA deficiency. PTA deficiency was found to exist in two forms:major PTA deficiency, characterized by PTA levels of up to 20 per cent of ourstandard reference plasma and by the potential for serious surgical bleeding,and minor PTA deficiency, characterized by PTA levels between 30 and 65per cent of our standard reference plasma and by the absence of significantsurgical bleeding. Minor PTA deficiency was found in parents and childrenof subjects with major PTA deficiency.

It would appear that the gene for PTA deficiency is an incompletely recessive or "intermediate" gene which produces major PTA deficiency in the homozygote and minor PTA deficiency in the heterozygote.

Submitted on March 27, 1961 Accepted on May 16, 1961     

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 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.     

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.     

Factor XI deficiency caused by a mutation of Gly400Val

The patient described herein is a 69-year-old Japanese woman with a history of excessive bleeding after left heminephrectomy for a malignant renal tumor at 31 years of age. Her parents, who do not have abnormal bleeding, are first cousins. Her factor XI activity was less than 1% of normal with an prolonged activated partial thromboplastin time (APTT) of 74.3 seconds. Analysis of the patient's factor XI genes revealed homozygosity for a valine substituting for the wild-type glycine at amino acid 400 (Gly400Val). The patient has two children, neither of whom has abnormal bleeding and whose factor XI activities are 62% and 57% of normal, with APTT levels within normal limits in both cases. We herein report on a Japanese family with factor XI deficiency caused by Gly400Val mutation.     

Combined dys-form of homozygous factor XI deficiency and heterozygous factor XII deficiency

A 12-year-old girl with lifelong hemorrhagic episodes was found to have both a dys-form of homozygous factor XI deficiency and heterozygous factor XII deficiency. The heredity of the coagulation defects was confirmed by family studies. Severe bleeding after dental surgery occurred in spite of replacement therapy and local measures including fibrin glue. Our findings suggest that the risk of bleeding in patients with homozygous factor XI deficiency must not be underestimated and that the most effective measure is the transfusion of sufficient amounts of fresh frozen plasma until at least the 5th postoperative day.     

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.     

Factor XI deficiency acquired by liver transplantation

Factor XI deficiency (the Rosenthal syndrome), an autosomal recessive genetic defect, was transmitted to a patient after orthotopic liver transplantation. The deficiency was manifested by an isolated prolonged activated partial thromboplastin time (aPTT) after surgery. Hematologic evaluation using specific factor analysis revealed an absolute deficiency of factor XI. Stored serum obtained from the organ recipient before transplantation showed normal factor XI levels. When the liver donor's family was questioned, it was discovered that he was of Ashkenazi Jewish descent and that he had a history of bleeding after dental procedures. Before his death from intracerebral bleeding, he was documented to have an isolated prolonged aPTT value. This case shows that potentially morbid genetic defects can be transmitted by organ transplantation. It also provides evidence confirming that the liver is the only site of factor XI production.     

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.     

Plasma thromboplastin antecedent (PTA, factor XI): a specific and sensitive radioimmunoassay

A specific, sensitive, and reproducible radioimmunoassay for human plasma thromboplastin antecedent (PTA, factor XI) has been developed with purified PTA and monospecific rabbit antiserum. Precise measurements of PTA antigen were possible for concentrations as low as 0.3% of that in normal pooled plasma. Normal plasma contained approximately 6 microgram PTA/ml. A good correlation (correlation coefficient 0.68) existed between the PTA procoagulant assays and radioimmunoassays among 50 normal adults (25 males and 25 females). PTA antigen was markedly reduced in plasma of 13 patients with congenital homozygous PTA deficiency (range less than 0.003-0.128 U/ml) and 9 patients with hepatic cirrhosis (0.35+/-0.17 U/ml), but was normal in those of 9 patients under treatment with warfarin, 8 patients with disseminated intravascular coagulation and 16 patients with other congenital clotting factor abnormalities, including prekallikrein deficiency (Fletcher trait) and high molecular weight kininogen deficiency (Fitzgerald trait).     

Four novel FXI gene mutations in three factor XI- deficient patients.

Hereditary factor XI deficiency is a mild bleeding disorder, which is highly prevalent among Ashkenazi Jews, but has been reported in all populations. In Ashkenazi Jews, two factor XI gene mutations Glu 117X (type II) and Phe283Leu (type III) are particularly common. In other ethnic groups, factor XI deficiency is a rare bleeding disorder and is related to a variety of mutations throughout the factor XI gene. Three cases of quantitative factor XI deficiency in relation with four novel missense mutations are reported: a compound heterozygosity for two novel mutations (Ala 181 Val and Ala 412 Thr) with a severe factor XI deficiency and two missense mutations (His 388 Pro and Trp 407 Cys) in heterozygous patients with partial factor XI deficiency.     

One of the two common mutations causing factor XI deficiency in Ashkenazi Jews (type II) is also prevalent in Iraqi Jews, who represent the ancient gene pool of Jews [see comments]

In recent years four mutations causing factor XI deficiency have been identified in Jews of Ashkenazi (European) origin. Two of them, type II (a nonsense mutation) and type III (a missense mutation), were found to prevail among 125 unrelated Ashkenazi Jews with severe factor XI deficiency. A finding of type II mutation in four unrelated Iraqi- Jewish families raised the possibility that this mutation is also common in Iraqi Jews, who represent the ancient gene pool of the Jews. A molecular-based analysis performed in 1,040 consecutively hospitalized patients disclosed the following results: Among 531 Ashkenazi-Jewish patients, the type II allele frequency was 0.0217 and among 509 Iraqi-Jewish patients, 0.0167 (P = .50). The type III allele frequency in the Ashkenazi-Jewish patients was 0.0254, whereas none of 502 Iraqi-Jewish patients examined had this mutation. These data suggest that the type II mutation was present in Jews already 2.5 millenia ago. The data also indicate that the estimated risk for severe factor XI deficiency in Ashkenazi Jews (due to either genotype) is 0.22% and in Iraqi Jews, 0.03%, and that the estimated risk of heterozygosity in Ashkenazi Jews is 9.0% and in Iraqi Jews, 3.3%. As patients with severe factor XI deficiency are prone to bleeding after injury and patients with partial deficiency may have similar bleeding complications when an additional hemostatic derangement is present, the observed high frequencies should be borne in mind when surgery is planned for individuals belonging to these populations.     

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.