Pregnancy outcome in Factor XI deficiency: incidence of miscarriage, antenatal and postnatal haemorrhage in 33 women with Factor XI deficiency

Pregnancy complications in women with Factor XI deficiency were assessed in this retrospective analysis. All nonnulliparous women registered with Factor XI deficiency in the East Midlands region were included. Each woman was classified into 'bleeder' or 'nonbleeder'. Rates of antenatal and postnatal bleeding and miscarriage rate were recorded. A total of 33 women had 105 pregnancies. Pregnancy and delivery was uneventful in 70% of the cases. Postpartum haemorrhage (PPH) appears increased in women with a 'bleeding' phenotype with a highly significant difference between 'bleeders' and 'nonbleeders' (relative risk [RR] 7.2; CI 1.99–25.9). Miscarriage rate appeared unchanged. We conclude that PPH is increased in a subgroup with a bleeding phenotype. Larger studies are needed to define the underlying factors.     

Hereditary plasma thromboplastin antecedent (PTA,FXI)

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.     

Is there a ‘Basque’ profile regarding autosomal recessive deficiencies of coagulation factors?*

When excluding haemophilia and von Willebrand disease, coagulation factors deficiencies constitute rare autosomal recessive disorders (<1 in 500,000) of less precisely defined epidemiology. We have reported herein the distribution of these entities in the French Basque Country, a genetic isolate of very old individualization with peculiar biological specificities. The prevalence of these disorders was markedly high, especially, as already shown, factor XI deficiency. This unusual profile needs to be discussed in the view of population genetics.     

Mutation analysis of two Japanese patients with Fanconi-Bickel syndrome

Fanconi-Bickel syndrome (FBS), or glycogen storage disease type XI, is a rare autosomal recessive disorder characterized by hepatorenal glycogen accumulation, Fanconi nephropathy, and impaired utilization of glucose and galactose. Recently, this disease was elucidated to link mutations in the glucose transporter 2 (GLUT2) gene. Only three mutations in three FBS families have been reported. Therefore, it is important to elucidate mutations in the GLUT2 gene in FBS by answering the question of whether the syndrome is a single gene disease. In this report, we describe two patients in two unrelated families clinically diagnosed with FBS. No mutation in the entire protein coding region of the GLUT2 gene was detected in patient 1, which suggested that no mutation existed in the GLUT 2 gene, or that some mutations had affected the expression of the GLUT 2 gene. In patient 2, a novel homozygous nonsense mutation (W420X, Trp at codon 420 to stop codon) was detected. These results support the correlation between GLTU2 gene mutation and FBS syndrome. However, many patients must be analyzed to determine whether other genes are involved in FBS. Received: July 16, 1999 / Accepted: September 3, 1999     

Plasma contact factors as therapeutic targets

Direct oral anticoagulants (DOACs) are small molecule inhibitors of the coagulation proteases thrombin and factor Xa that demonstrate comparable efficacy to warfarin for several common indications, while causing less serious bleeding. However, because their targets are required for the normal host-response to bleeding (hemostasis), DOACs are associated with therapy-induced bleeding that limits their use in certain patient populations and clinical situations. The plasma contact factors (factor XII, factor XI, and prekallikrein) initiate blood coagulation in the activated partial thromboplastin time assay. While serving limited roles in hemostasis, pre-clinical and epidemiologic data indicate that these proteins contribute to pathologic coagulation. It is anticipated that drugs targeting the contact factors will reduce risk of thrombosis with minimal impact on hemostasis. Here, we discuss the biochemistry of contact activation, the contributions of contact factors in thrombosis, and novel antithrombotic agents targeting contact factors that are undergoing pre-clinical and early clinical testing.     

Tamoxifen induces resistance to activated protein C

Introduction

The estrogen antagonist tamoxifen (TAM) increases the thrombotic risk similar to estrogen containing oral contraceptives (OC). In OC users this risk is attributed to alterations of hemostasis resulting in acquired resistance to activated protein C (APC). TAM-induced APC resistance has not been reported yet.

Materials and Methods

Blood samples were collected prospectively from women with breast cancer before (n = 25) and monthly after start of adjuvant TAM treatment (n = 75). APC resistance was evaluated on basis of the effect of APC on the endogenous thrombin generation potential. To detect increased in vivo APC generation APC plasma levels were measured using a highly sensitive oligonucleotide-based enzyme capture assay. Routine hemostasis parameters were measured additionally.

Results

APC sensitivity decreased by 41% (p = 0.001) compared to baseline after one month of TAM application and remained significantly decreased during the study period. Free protein S increased (p = 0.008) while other analyzed procoagulant factors, inhibitors, and activation markers of coagulation decreased or did not change significantly. In five patients the APC concentration increased to non-physiological levels but an overall significant increase of APC was not observed.

Conclusions

This is the first study showing acquired APC resistance under TAM therapy. Acquired APC resistance might explain the increased thrombotic risk during TAM treatment. Observed changes of hemostasis parameters suggest different determinants of TAM-induced APC resistance than in OC-induced APC resistance. The presence of acquired APC resistance in TAM patients warrants further evaluation if these patients may benefit from antithrombotic prophylaxis in the presence of additional thrombotic risk factors.     

In vitro evaluation of residual procoagulants in human intravenous immunoglobulins from 11 Chinese blood fractionation companies

Introduction

Residual procoagulants has been suggested to play an important role in the occurrence of thromboembolic events with intravenous immunoglobulin.

Objective

This study investigated the predominant plasma proteases in 81 intravenous immunoglobulin lots from 11 Chinese manufacturers to examine the procoagulants of these human therapeutic intravenous immunoglobulin products.

Methods

In one-stage clotting assays, the procoagulant activities of factors II, VII, IX, X, XI, and XII were quantified. Non-activated partial thromboplastin time and a modified thrombin generation test served as global and activated coagulation factor XI specific clotting assays, respectively.

Results

The coagulation factor clotting activities of the 78 intravenous immunoglobulin lots were below the detection limit of the assays. The time to peak of thrombin generation using a thrombin generation test was longer than 35 min. The relevant amount of activated coagulation factor XI was below 0.37 nM. Non-activated partial thromboplastin time was greater than 203 s, except for the three pilot samples of manufacturer B in which we observed 0.48 to 0.09 IU/mL factor XI lever, 20 to 26 min for the time to peak of thrombin generation, 0.54 to 37.99 nM activated coagulation factor XI, and 155 to 182 s for non-activated partial thromboplastin time.

Conclusions

The three intravenous immunoglobulin lots from manufacturer B showed significant procoagulant potential. Further study is required to determine whether a program for activated coagulation factor XI determination in intravenous immunoglobulin products should be launched in China.