Inhibitor in Congenital Factor VII Deficiency; a Rare but Serious Therapeutic Challenge-A Systematic Literature Review

Clinical, Laboratory, and Molecular Aspects of Factor VII Deficiency

Congenital factor VII (FVII) deficiency, the most frequent among the recessively inherited disorders of blood coagulation, is characterized by a wide range of symptoms, from mild mucosal bleeds to life-threatening intracranial hemorrhage. Complete FVII deficiency may cause perinatal lethality. Clinically relevant thresholds of plasma levels are still uncertain, and modest differences in low FVII levels are associated with large differences in clinical phenotypes. Activated FVII (FVIIa) expresses its physiological protease activity only in a complex with tissue factor (TF), which triggers clotting at a very low concentration. Knowledge of the FVIIa-TF complex helps to interpret the clinical findings associated with low FVII activity as compared with other rare bleeding disorders and permits effective management, including prophylaxis, with recombinant FVIIa, which, however, displays a short half-life. Newly devised substitutive and nonsubstitutive treatments, characterized by extended half-life properties, may further improve the quality of life of patients. Genetic diagnosis has been performed in thousands of patients with FVII deficiency, and among the heterogeneous F7 mutations, mostly missense changes, several recurrent variants show geographical distribution and identity by descent. In the general population, common F7 polymorphisms explain a large proportion of FVII level variance in plasma through FVII-lowering effects. Their combination with pathogenic variants may impact on the frequent detection of FVII coagulant levels lower than normal, as well as on mild bleeding conditions. In the twenties of this century, 70 years after the first report of FVII deficiency, more than 200 studies/reports about FVII/FVII deficiency have been published, with thousands of FVII-deficient patients characterized all over the world.

Interleukin 10, but not tumor necrosis factor-alpha, gene variations are associated with factor VII inhibitor development

OBJECTIVE

Development of alloantibodies against coagulation factor VII (FVII) is the main therapeutic challenge in severe congenital FVII deficiency. About 7% of patients with severe congenital FVII deficiency develop an inhibitor against FVII. In this research, the relationship between interleukin (IL)-10 and tumor necrosis factor-alpha (TNF)-α gene variants and inhibitor development was evaluated for a group of Iranian patients with severe congenital factor VII deficiency.

METHODS

Patients with FVII deficiency were divided into 2 groups: 6 cases and 15 controls. Genotyping was performed using the amplification-refractory mutation system polymerase chain reaction.

RESULTS

We found that IL-10 rs1800896 A>G gene variant is associated with the risk of FVII inhibitor development (OR = 0.077, 95% CI = 0.016-0.380, P = .001), whereas the TNFα-rs1800629G>A variant has no relation with inhibitor development in severe FVII deficiency.

CONCLUSION

The results show that the IL-10 rs1800896 A>G variant increases the risk of developing an inhibitor in patients with severe congenital FVII deficiency.

Management of rare inherited bleeding disorders: Proposals of the French Reference Centre on Haemophilia and Rare Coagulation Disorders

INTRODUCTION

The rare coagulation disorders may present significant difficulties in diagnosis and management. In addition, considerable inter-individual variation in bleeding phenotype is observed amongst affected individuals, making the bleeding risk difficult to assess in affected individuals. The last international recommendations on rare inherited bleeding disorders (RIBDs) were published by the United Kingdom Haemophilia Centre Doctors' Organisation in 2014. Since then, new drugs have been marketed, news studies on surgery management in patients with RIBD have been published, and new orphan diseases have been described.

AIM

Therefore, the two main objectives of this review, based on the recent recommendations published by the French Reference Centre on Haemophilia and Rare Bleeding Disorders, are: (i) to briefly describe RIBD (clinical presentation and diagnostic work-up) to help physicians in patient screening for the early detection of such disorders; and (ii) to focus on the current management of acute haemorrhages and long term prophylaxis, surgical interventions, and pregnancy/delivery in patients with RIBD.

Factor VII deficiency in China: Phenotype, genotype and current status of management

Congenital factor VII (FVII) deficiency is a rare bleeding disorder characterised by a wide molecular and clinical heterogeneity. We investigated the clinical phenotype of 193 patients and F7 genotype of 55/193 patients with FVII deficiency throughout China and showed their current status of management. The most frequent bleeding symptoms were epistaxis (44.6%), cutaneous (38.9%), oral cavity (40.4%) bleeding and menorrhagia (44.3% of females of reproductive age). Fatal central nervous system bleeding and disabling joint bleeding occurred in three patients each. The majority of patients (89.6%) had FVII activity (FVII:C) ≤10% and the proportion of symptomatic patients in this group (79.8%) was significantly higher than that in the groups with FVII:C >10%-25% (41.7%) and >25%-50% (37.5%) (χ² = 13.641, p = 0.001). Major bleeds occurred only in patients with FVII:C ≤10%. In total 55 patients underwent genotype analysis: most variants were missense (62.5%) and most patients had homozygous/compound heterozygous (85.4%) variants. Prothrombin complex concentrates (72.4%) were the most frequently used on-demand replacement therapy. Prophylaxis before delivery decreased the risk of postpartum bleeding in women (χ² = 69.243, p = 0.000). Our study provides useful information on the phenotype, genotype and current status of FVII-deficiency patients management and may promote further exploration and care of this population in the future.

Risk and Management of Intracerebral Hemorrhage in Patients with Bleeding Disorders

Intracerebral hemorrhage (ICH) is the most dreaded complication, and the main cause of death, in patients with congenital bleeding disorders. ICH can occur in all congenital bleeding disorders, ranging from mild, like some platelet function disorders, to severe disorders such as hemophilia A, which can cause catastrophic hemorrhage. While extremely rare in mild bleeding disorders, ICH is common in severe coagulation factor (F) XIII deficiency. ICH can be spontaneous or trauma-related. Spontaneous ICH occurs more often in adults, while trauma-related ICH is more prevalent in children. Risk factors that can affect the occurrence of ICH include the type of bleeding disorder and its severity, genotype and genetic polymorphisms, type of delivery, and sports and other activities. Patients with hemophilia A; afibrinogenemia; FXIII, FX, and FVII deficiencies; and type 3 von Willebrand disease are more susceptible than those with mild platelet function disorders, FV, FXI, combined FV-FVIII deficiencies, and type 1 von Willebrand disease. Generally, the more severe the disorder, the more likely the occurrence of ICH. Contact sports and activities can provoke ICH, while safe and noncontact sports present more benefit than danger. An important risk factor is stressful delivery, whether it is prolonged or by vacuum extraction. These should be avoided in patients with congenital bleeding disorders. Familiarity with all risk factors of ICH can help prevent occurrence of this diathesis and reduce related morbidity and mortality.

Molecular Characterization of Two Homozygous Factor VII Variants Associated with Intracranial Bleeding

Clinical parameters have been extensively studied in factor (F) VII deficiency, but the knowledge of molecular mechanisms of this disease is scarce. We report on three probands with intracranial bleeds at an early age, one of which had concomitant high titer of FVII inhibitor. The aim of the present study was to identify the causative mutations and to elucidate the underlying molecular mechanisms. All nine F7 exons were sequenced in the probands and the closest family members. A homozygous deletion in exon 1, leading to a frame shift and generation of a premature stop codon (p.C10Pfs*16), was found in proband 1. Probands 2 and 3 (siblings) were homozygous for a missense mutation in exon 8, resulting in a glycine (G) to arginine (R) substitution at amino acid 240 (p.G240R). All probands had severely reduced FVII activity (FVII:C < 1 IU/dL). Treatment consisted of recombinant FVIIa and/or plasma concentrate, and proband 1 developed a FVII inhibitor shortly after initiation of treatment. The FVII variants were overexpressed in mammalian cell lines. No FVII protein was produced in cells expressing the p.C10Pfs*16 variant, and the inhibitor development in proband 1 was likely linked to the complete absence of circulating FVII. Structural analysis suggested that the G to R substitution in FVII found in probands 2 and 3 would destabilize the protein structure, and cell studies demonstrated a defective intracellular transport and increased endoplasmic reticulum stress. The molecular mechanism underlying the p.G240R variant could be reduced secretion caused by protein destabilization and misfolding.