Arg77His and Trp187Arg are the most common mutations causing FXIII deficiency in Iran

Postpartum Hemorrhage in Heterozygote Factor XIII Deficient Women Compared With Healthy Women. A Cross-Sectional Experience From Iran

Postpartum hemorrhage (PPH) is a major cause of maternal mortality, which is a common clinical manifestation in women with rare bleeding disorders. In this study, we compare PPH and its complications in heterozygote factor XIII (FXIII) deficient women with healthy women. In this cross sectional case study, 50 women with heterozygote FXIII deficiency and 50 healthy women are evaluated. Data were initially collected by interviewing the women who were receiving FXIII replacement therapy after their childbirths. Data were analysed using SPSS (Version 22) and a P-value of less than .05 was considered statistically significant. The mean age in the patient and control groups were 31.2 and 32.5 years respectively. The occurring rate of PPH in the patient group was significantly higher than the control group (34% vs 2%) (P-value <.0001). None of the confounding variables such as maternal age, gestational age, numbers, and types of delivery in women with PPH showed any significant differences between the control and patient groups. According to the results of this study, the risk of PPH (early and late), miscarriage, and menorrhagia in women who are heterozygous for FXIII deficiency is significantly higher than healthy women. However, the effect of other factors such as maternal age, gestational age, number, and type of delivery require further studies to delineate any confounding factors.

How to Assess Founder Effect in Patients with Congenital Factor XIII Deficiency

Congenital factor XIII (FXIII) deficiency is an extremely rare bleeding disorder (RBD) with estimated prevalence of one per 2 million in the general population. The disorder causes different clinical manifestations such as intracranial hemorrhage (ICH), recurrent miscarriage, umbilical cord bleeding, etc. High incidence of the disorder might be due to founder effect. To assess founder effect, haplotype analysis is an important step. For this purpose, suitable and reliable genetic markers such as microsatellites (Hum FXIIIA01 and HumFXIIIA02) and single nucleotide polymorphisms (SNP) are suggested. In the present study we tried to describe evaluation of founder effect in patients with congenital FXIII deficiency via haplotype analysis using suitable genetic markers.

State of the art in factor XIII laboratory assessment

Factor XIII, a heterotetrameric proenzyme, is converted to an activated transglutaminase by thrombin and calcium in the final phases of coagulation. Factor XIII catalyzes the formation of crosslinks between fibrin monomers and between α2-antiplasmin and fibrin. These crosslinks mechanically stabilize fibrin against shear stress, enable red cell retention within the clot, and protect the clot from premature degradation. Congenital factor XIII deficiency is caused by autosomal recessive mutations, presenting early in life with a severe bleeding diathesis. Acquired deficiency may be caused by autoimmunity. Currently available assays for laboratory diagnosis of factor XIII deficiency include clot solubility assays, quantitative factor XIII activity assays, factor XIII antigen assays, and genetic testing. The International Society on Thrombosis and Haemostasis Scientific and Standardization Committee has recommended an algorithm for the laboratory diagnosis and differentiation of the different forms of factor XIII deficiency. However, implementation of this algorithm has been limited by technical and budgetary challenges associated with the currently available factor XIII-specific assays. The purpose of this review is to discuss the advantages and limitations of the currently available assays employed for the laboratory diagnosis of factor XIII deficiency.

Factor XIII deficiency diagnosis: Challenges and tools

Factor XIII deficiency (FXIIID) is a rare hereditary bleeding disorder arising from heterogeneous mutations, which can lead to life-threatening hemorrhage. The diagnosis of FXIIID is challenging due to normal standard coagulation assays requiring specific FXIII assays for diagnosis, which is especially difficult in developing countries. This report presents an overview of FXIIID diagnosis and laboratory methods and suggests an algorithm to improve diagnostic efficiency and prevent missed or delayed FXIIID diagnosis. Assays measuring FXIII activity: The currently available assays utilized to diagnose FXIIID, including an overview of their complexity, reliability, sensitivity, and specificity, as well as mutational analysis are reviewed. The use of a FXIII inhibitor assay is described. Diagnostic tools in FXIIID: Many laboratories are not equipped with quantitative FXIII activity assays, and if available, limitations in lower activity ranges are important to consider. Clot solubility tests are not standardized, have a low sensitivity, and are therefore not recommended as routine screening test; however, they are the first screening test in almost all coagulation laboratories in developing countries. To minimize the number of patients with undiagnosed FXIIID, test quality should be improved in less well-equipped laboratories. Common country-specific mutations may facilitate diagnosis through targeted genetic analysis in reference laboratories in suspected cases. However, genetic analysis may not be feasible in every country and may miss spontaneous mutations. Centralized FXIII activity measurements should also be considered. An algorithm for diagnosis of FXIIID including different approaches dependent upon laboratory capability is proposed.

Assessment of Factor XIII

Blood coagulation factor XIII (FXIII) is essential for maintaining hemostasis. The absence of FXIII results in severe bleeding diathesis, which without prophylaxis frequently leads to fatal bleeding. As the usual hemostasis screening tests remain normal, the diagnosis of FXIII deficiency needs specific tests. Here, we describe FXIII activity determination by the ammonia release assay, which is the first-line test in the diagnostic algorithm for FXIII deficiency. The method for another activity test, the undeservedly rarely used fibrin cross-linking assay, is also presented. Further tests used for the classification of FXIII deficiencies, measurement of FXIII activity in platelets, ELISAs for the measurement of complex plasma FXIII (FXIII-A₂B₂) antigen and for FXIII-A₂ in plasma and platelets are also included. Detailed description of the methods for the detection and measurement of neutralizing auto- and alloantibodies is also provided.

Clinical manifestations and management of life-threatening bleeding in the largest group of patients with severe factor XIII deficiency

Factor XIII (FXIII) deficiency is a rare hemorrhagic disorder for which the highest incidence occurs in southeast Iran. The aim of this study was to assess molecular characteristics, clinical manifestations and management of life-threatening diathesis in FXIII deficiency. This study was conducted on 190 patients with FXIII deficiency. Genotype analysis for the most frequent mutation of FXIII-A subunit gene in Iranian, Trp187Arg, was performed for all patients. Clinical manifestations and management of patients with intracranial hemorrhage (ICH), miscarriage and neonates with FXIII deficiency were documented. Neonates were divided in two groups: Group 1 received a standard dose of Fibrogammin P(®) (10-26 IU/Kg) and group 2 received a high dose of this drug (60-80 IU/Kg) for 36 months. Bleeding episodes in both groups were recorded, and neonates of group 2 were regularly checked for thrombotic events. Molecular analysis revealed that all patients were homozygous for Trp187Arg mutation. Umbilical bleeding, hematoma and prolonged wound bleeding were common presentations. ICH was another common presentation leading to behavioral and developmental disorders and aphasia. ICH was managed by Fibrogammin P(®) at a dose of 10-26 IU/Kg, and miscarriage was managed by Fibrogammin P(®) at a dose of 10 IU/Kg every 2 weeks during pregnancy, and the same dose administered as prophylaxis before gestation every 4 weeks. Neonates of group 2 received 60-80 IU/kg dose of Fibrogammin P(®). This higher dose did not trigger thrombotic events but significantly decreased bleeding episodes and prevented the occurrence of major bleeding. Trp187Arg is the most common mutation of FXIII-A subunit in Iran, and Fibrogammin P(®) is effective in the management of FXIII deficiency, and higher dose of this drug is safe and effective in neonates.