Five new F10 variants in hereditary factor x deficiency detected by high-throughput sequencing.

INTRODUCTION: Factor X deficiency is a rare inherited bleeding disorder. To date, 181 variants are reported in the recently updated F10-gene variant database. AIM: This study aimed to describe new F10 variants. METHOD: The F10 gene was analysed in 16 consecutive families with FX deficiency by a targeted high-throughput sequencing approach, including F10, F9, F8 genes, and 78 genes dedicated to haematological malignancies. RESULTS: We identified 19 variants (17 missense, one nonsense and one frameshift) and two copy number variations. Two patients presenting a combined FVII-FX deficiency showed a loss of one F10 gene copy (del13q34) associated with a missense variant on the remaining allele, leading to a FX:C significantly lower than the FVII:C level and explaining their unusual bleeding history. We reported five novel variants. Three missense variants (p.Glu22Val affecting the signal peptide cleavage site, p.Cys342Tyr removing the disulphide bond between the FX heavy and light chains, and p.Val385Met located in FX peptidase S1 domain) were detected at compound heterozygosis status in three patients with severe bleeding symptoms and FX:C level below 10 IU/dL. Two truncating variants p.Tyr279* and p.Thr434Aspfs*13 leading to an altered FX protein were found at heterozygous state in two patients with mild bleeding history. CONCLUSION: This study showed the feasibility and the interest of high-throughput sequencing approach for rare bleeding disorders, enabling the report of F10 gene screening in a 3-weeks delay, suitable for clinical use. The description of five new variants may contribute to a better understanding of the phenotype-genotype correlation in FX deficiency.

Postmortem diagnosis of severe factor X deficiency in a fetus with intracranial hemorrhage resulting in intrauterine death.

In patients with severe congenital factor X deficiency, spontaneous intracranial hemorrhage (ICH) is particularly frequent in early childhood. We describe a case of fetal death at 26 weeks due to massive ICH. Gene panel analysis of postmortem samples revealed homozygosity for a pathologic F10 gene variant (c.1210T>C, p.Cys404Arg), which impedes correct folding of the catalytic serine protease domain and, therefore, causes a significant reduction in FX levels. The parents, not consanguineous but of the same ethnic community, were found to be heterozygous for this variant and did not have any personal or family history of abnormal bleeding. To the best of our knowledge, this is the first reported case of severe FX deficiency resulting in ICH diagnosed through postmortem genetic analysis. It illustrates the importance of exploring the etiology of fetal or neonatal ICH, which may impact future pregnancies, and the treatment of a potential coagulopathy in the child.

[Congenital factor X deficiency: a retrospective analysis of 11 cases].

Objective: To analyze the clinical characteristics, laboratory examination, diagnosis, treatment, and outcome of hereditary factor Ⅹ (FⅩ) deficiency. Methods: Clinical data of 11 patients with congenital FⅩ deficiency were retrospectively analyzed from July 2009 to February 2021. Results: There were 3 males and 8 females. Median age was 39 (5-55) years. The media duration of follow-up was 81.67 (1.87-142.73) months. Of the 11 patients, 10 had bleeding symptoms, 7 had ecchymosis or hemorrhage after skin bump, 7 had nosebleed, 6 had gingival hemorrhage, and 1 had muscle hematoma. Among the female patients, 6 had menorrhagia and 1 experienced bleeding after vaginal delivery. Family history of FⅩ deficiency was found in one case. Eight patients had a history of surgery, and four had postoperative bleeding. Laboratory findings were characterized by significantly prolonged activated partial thromboplastin time, prothrombin time, and decreased FⅩ activity (FⅩ∶C) . Four cases underwent gene mutation analysis and five new mutations were found. Four cases were treated with prothrombin complex concentrates (PCC) and seven cases with fresh frozen plasma (FFP) . One female patient had significantly reduced menstrual volume after PCC prophylactic therapy. One patient received FFP for prophylactic infusion with no bleeding during and after the operation. Conclusion: Most patients with congenital FⅩ deficiency had bleeding symptoms and there was no significant correlation between severity of bleeding symptoms and FⅩ∶C. Prophylaxis should be applied in patients with severe bleeding tendencies. Gene mutation test is significant for screening, diagnosis, and prognosis prediction of congenital FX deficiency.

Genotypes and phenotypes characterization of 17 Iranian patients with inherited factor X deficiency: identification of a novel mutation: Leu487Phe.

Factor X deficiency is a rare bleeding disorder that affects almost 1 : 1000 000 people worldwide. It derives from multiple mutational changes in the factor X gene (F10). The main objective of the present study was to determine a consistent correlation between the clinical presentations and causative genotype. The phenotype and genotype of 17 Iranian patients with reduced factor X activity (FX:C) from 14 unrelated families were analyzed to screen factor X gene expression for any possible mutations and function alteration. Analysis of the sequencing results led to the identification of eight different mutations besides a single nucleotide variation. One of the mutations was novel (Leu487Phe) as studied by means of online analysis programs and molecular modeling. Eight patients were homozygote; three were heterozygote, while six out of 17 patients were symptomatic cases without any mutations. The Arg40Thr missense mutation was detected in three patients including two siblings and was associated with severe bleeding symptoms. Also, two patients were identified with Gly262Asp missense mutation which commonly presented with bleeding disorder. Each of the other patients was associated with a unique missense mutation including one novel mutation in which the tentative relation of the mutation to bleeding symptoms is reported. Mutations leading to a FX:C of less than 1% are associated with severe bleeding symptoms confirming the strong correlation between clinical severity and FX:C. The novel Leu487Phe mutation with FX:C of 13% may have possible negative effects on factor X protein function resulting in minor clinical manifestation.

Diagnosis, therapeutic advances, and key recommendations for the management of factor X deficiency.

Factor X deficiency is a rare coagulation disorder that can be hereditary or acquired. The typology and severity of the associated bleeding symptoms are highly heterogeneous, adding to the difficulties of diagnosis and management. Evidence-based guidelines and reviews on factor X deficiency are generally limited to publications covering a range of rare bleeding disorders. Here we provide a comprehensive review of the literature on factor X deficiency, focusing on the hereditary form, and discuss the evolution in disease management and the evidence associated with available treatment options. Current recommendations advise clinicians to use single-factor replacement therapy for hereditary disease rather than multifactor therapies such as fresh frozen plasma, cryoprecipitate, and prothrombin complex concentrates. Consensus in treatment guidelines is still urgently needed to ensure optimal management of patients with factor X deficiency across the spectrum of disease severity.

A Compound Heterozygosis of Two Novel Mutations Causes Factor X Deficiency in a Chinese Pedigree.

BACKGROUND: Mutations in the F10-coding gene can cause factor X (FX) deficiency, leading to abnormal coagulation activity and severe tendency for hemorrhage. Therefore, identifying mutations in F10 is important for diagnosing congenital FX deficiency. METHODS: We studied a 63-year-old male patient with FX deficiency and 10 of his family members. Clotting and immunological methods were used to determine activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen levels, FX activity, and FX antigen levels. The platelet count was determined. A mixing study was performed to eliminate the presence of coagulation factor inhibitors and lupus anticoagulant. Mutations were searched using whole-exome sequencing and certified by Sanger sequencing. RESULTS: Genetic analysis of the proband identified two single-base substitutions: c.1085G>A (p.Ser362Asn) and c.1152C>A (p.Tyr384Ter, termination codon, caused by the DNA sequence TAA). His FX activity and antigen levels were 1.7% and 408.53 pg/mL, respectively; aPTT and PT were 52.3 and 48.0 s, respectively. One brother had the same compound heterozygous mutations, and his FX activity and antigen levels were 1.3% and 465.47 pg/mL, respectively; his aPTT and PT were 65.2 and 54.5 s, respectively. His mother, another brother, and one sister were heterozygous for c.1085G>A (p.Ser362Asn), and his daughter and grandson (6 years old) were heterozygous for c.1152C>A (p.Tyr384Ter). CONCLUSION: The heterozygous variants p.Ser362Asn or p.Tyr384Ter indicate mild FX deficiency, but the compound heterozygous mutation of the two causes severe congenital FX deficiency and bleeding. Genetic analysis of these two mutations may help characterize the bleeding tendency and confirm congenital FX deficiency.

Molecular mechanism of a novel Ser362Asn mutation causing inherited FX deficiency in a Chinese family.

Factor X (FX) deficiency is an inherited autosomal recessive bleeding disorder. Here, we analyzed a proband with FX deficiency in a Chinese family. Genetic analysis revealed that the proband and his affected sister was homozygous for c.1085G>A mutation, corresponding to a Ser362Asn substitution. In vitro expression experiments showed that the FX Ser362Asn mutation led to a significant reduction in activity levels in the culture medium. This Ser to Asn substitution may change the shape of the active site. Moreover, simulations of molecular dynamics indicated that the binding energy of the FX Ser362Asn to the substrate is higher than that of wild type and the side-chain conformation of the catalytic residue His276 (His42) is changed. This impairs the conformational switch of the protein from zymogen to proteinase, thus causing the functional defect of FX protein. Our findings suggest that the Ser362Asn substitution is a pathogenic mutation that causes inherited FX deficiency.

Genetic analysis of a compound heterozygous patient with congenital factor X deficiency and regular replacement therapy with a prothrombin complex concentrate.

Congenital factor X (FX) deficiency is a rare bleeding disorder with an incidence of one in one million. The proband, a 2-year-old girl, exhibited easy bruising and a history of umbilical cord bleeding at birth. Prothrombin time (> 40 s) and activated partial thromboplastin time (65.0 s) were prolonged. Marked declines in FX activity (< 1%) and FX antigen levels (5%) were also observed. Genetic analysis of the proband identified two types of single-base substitutions, c.353G>A (p.Gly118Asp) and c.1303G>A (p.Gly435Ser), indicating compound heterozygous congenital FX deficiency. Genetic analysis of family members revealed that her father and older sister (5-year-old) were also heterozygous for p.Gly118Asp, and that her mother was heterozygous for p.Gly435Ser. To improve the bleeding tendency, the proband received regular replacement of 500 units of PPSB-HT, a prothrombin complex concentrate (PCC). Following continued regular replacement of 500 units of PPSB-HT once per week, the proband has exhibited no bleeding tendencies and no new bruises have been observed. There are no previous report of the use of PPSB-HT for regular FX replacement. Regular replacement therapy with PPSB-HT may be an effective method for preventative control of bleeding tendencies in FX deficiency.

Plasma-derived Factor X therapy for treatment of intracranial bleeding in a patient with Factor X deficiency: a case report.

BACKGROUND: Factor X (FX) deficiency (FXD) is an extremely rare autosomal recessive hereditary hematologic disorder, affecting approximately one in 1,000,000 of the general population. CASE REPORT: This case report describes an infant with hereditary severe FXD who presented with a spontaneous, life-threatening intracranial hemorrhage and was treated with the first licensed plasma-derived FX (pdFX) concentrate. On admission, laboratory assays showed severe coagulopathy of unknown cause; the patient was empirically treated using a multimodal hemostatic approach with prothrombin complex concentrate, fresh-frozen plasma, and tranexamic acid. Subsequent single-factor coagulation and genetic analyses confirmed the hereditary FXD diagnosis, and the therapeutic regimen was changed to a targeted regimen of 250 IU pdFX daily. Based on careful monitoring of the coagulation profile, pdFX administration frequency was increased to twice daily, followed by a reduction to once every 18 hours. The patient was discharged after 7 weeks of hospitalization in good clinical condition and now receives prophylactic pdFX three times weekly.

The Disulfide Bond between Cys22 and Cys27 in the Protease Domain Modulate Clotting Activity of Coagulation Factor X.

The Cys22-Cys27 disulfide bond of factor X (FX) protease domain is not conserved among coagulation factors and its contribution to the physiological haemostasis and implication in the pathogenesis of haemostatic and thrombotic disorders remain to be elucidated. Mutation p.Cys27Ser was identified in a pedigree of congenital FX deficiency and fluorescence labelling study of transiently transfected HEK293 cells showed accumulation of FX p.Cys27Ser within cell, indicating incompetent secretion partially responsible for the FX deficiency. The clotting activity of FX p.Cys27Ser was decreased to about 90% of wild-type, while amidolytic and pro-thrombinase activities (kcat/Km) determined with recombinant FXa mutant were 1.33- and 4.77-fold lower. Molecular dynamic simulations revealed no major change in global structure between FXa p.Cys27Ser and wild-type FXa; however, without the Cys22-Cys27 disulfide bond, the insertion of newly formed N terminal of catalytic domain after the activation cleavage is hindered, perturbing the conformation transition from zymogen to enzyme. The crystal structure of FXa shows that this disulfide bond is solvent accessible, indicating that its stability might be subject to the oxidation/reduction balance. As demonstrated with FX p.Cys27Ser here, Cys22-Cys27 disulfide bond may modulate FX clotting activity, with reduced FX pertaining less pro-coagulant activity.

Cutaneous adverse event associated with vemurafenib in a 3-year-old pediatric patient with BRAF mutation-positive metastatic melanoma and factor X deficiency.

Malignant melanoma is very rare in childhood. The approach to diagnosis and treatment in children has been adopted from adult guidelines. Vemurafenib is indicated in adults with BRAF V600 mutation-positive stage IIIc/IV melanoma and causes cutaneous adverse events. We report on a 3-year-old child with recurrent, metastatic (bone) BRAF mutation-positive melanoma. He also had severe factor X deficiency. Four days after vemurafenib treatment, bilateral palpebral edema and violet-colored hyperpigmentation were observed. There was no objective response to vemurafenib; however, bone pain regressed slightly. Our patient is the youngest patient who received vemurafenib for BRAF V600 mutation-positive metastatic melanoma in the literature.

Genotype analysis and identification of novel mutations in a multicentre cohort of patients with hereditary factor X deficiency.

: The objective was to examine the genotypic and phenotypic characteristics of individuals with hereditary factor X deficiency (FXD), a rare autosomal recessive bleeding disorder caused by mutations in the F10 gene located on chromosome 13q34-ter. To date, 149 F10 mutations have been identified as contributory to FXD. Three open-label phase 3 trials enrolled individuals with mild, moderate, or severe FXD. Individuals received plasma-derived factor X concentrate as routine prophylaxis, to treat bleeds, and/or during or after surgery. F10 genotyping was performed (studies 1 and 2) or genotype data was collected at screening (study 3), and identified F10 mutations were compared against the Human Gene Mutation Database to assess novelty. Genotype data were combined to evaluate the number, type, and novelty of the F10 mutations identified. Genotype data were available for 24 of 27 individuals with mild (n = 2), moderate (n = 2), or severe (n = 20) FXD. Analyses identified 22 separate mutations, including 15 missense mutations, 2 deletions, 4 splice site mutations, and 1 nonsense mutation. Sixteen individuals had homozygous mutations; 8 had compound heterozygous mutations. Eleven unique novel mutations (all compound heterozygous) were identified in seven individuals: six missense mutations, three splice site mutations, one exon deletion, and one nonsense mutation. In silico analyses strongly supported the pathogenicity of all novel mutations. The identification of 11 novel F10 mutations provides a substantial contribution to the mutations known to cause FXD.

Factor X Deficiency Due to a Compound Heterozygosis Between a New Mutation (Gla72Asp) in Exon 2 and an Already Known one (Gly154Arg) in Exon 5: Factor X Mar Del Plata1).

BACKGROUND: Investigation of rare bleeding disorders in Latin-America. OBJECTIVES: The report of a new case of FX deficiency due to a compound heterozygosis. METHODS: Accepted clotting procedures were used. Sequencing of DNA was carried out by means of Applied Biosystems Instruments. RESULTS: A compound heterozygote due to the association of a new mutation (Gla72Asp) with an already known mutation (Gly154Arg) of the FX gene is reported. The proposita is a 38 year old female who had a moderate bleeding tendency (menorrhagia, epistaxis, easy bruising). The proposita has never received substitution therapy but in the occasion of a uterine biopsy. The mother was asymptomatic but was a heterozygote for the new mutation. The father was asymptomatic but had deserted the family and could not be investigated. After this abandonment the mother of the proposita re-married with an asymptomatic man and she gave birth to a son who was asymptomatic but was also heterozygous for the new mutation (Gla72Asp). As a consequence it has to be assumed that the first husband of the mother of the proposita was heterozygous for the known mutation (Gly154Arg). CONCLUSIONS: This is the third case of a new mutation in the FX gene reported, during the past few years, in Argentina.

[Genotypic and phenotypic analysis of a case with inherited coagulation factor X deficiency].

OBJECTIVE: To explore the correlation between F10 gene mutation and its phenotype in a Chinese pedigree affected with FX deficiency. METHODS: Prothrombin time(PT), activated partial thromboplastin time(APTT), fibrinogen, FII activity(FII:C), FVII activity(FVII:C), FIX activity (FIX:C), FX activity(FX:C) were determined with a one-stage clotting assay. The FX antigen(FX:Ag) was detected with an enzyme linked immunosorbent assay(ELISA). The 8 exons, introns and 5' and 3' untranslated regions(UTR) of the F10 gene of the proband and her family members were subjected to PCR amplification and Sanger sequencing. Suspected mutation was confirmed by reverse sequencing. Polymorphisms were excluded by direct sequencing of 100 healthy individuals. RESULTS: The PT and APTT of the proband have prolonged to 16.1 s and 49.0 s, respectively. Her FX:C and FX:Ag were reduced by 27% and 56%, and her mother's PT, APTT, FX:C and FX:Ag were 14.8 s, 37.4 s, 44%, 34%, respectively. Her grandmother's PT, APTT, FX:C and FX:Ag were 15.8 s, 42.2 s, 31%, 45%, respectively. The results of her father and other family members were all within the normal range. Genetic analysis has revealed a heterozygous G to A mutation in the proband at position 28076 in exon 8 of the F10 gene, which resulted in a p.Gly363Ser substitution. The same mutation was also found in her mother and grandmother. No mutation of the F10 gene was found in her father. Gly363Ser may result in changes in the secondary structure of the FX protein and reduction of its activity. CONCLUSION: The g.28076G to A(p.Gly363Ser) mutation of the F10 gene probably underlies the FX deficiency in this pedigree. The mutation was discovered for the first time in Chinese patients.

Congenital coagulation factor X deficiency: Genetic analysis of five patients and functional characterization of mutant factor X proteins.

Congenital factor X (FX) deficiency is a rare bleeding disorder that is inherited as an autosomal recessive trait. In this study, a genetic analysis of the FX gene was performed in five families with this disorder. Four heterozygous mutations [p.Gly154Arg, p.Val236Met, p.Gly263Val and p.Arg387Cys] and one pair of compound heterozygous FX gene mutations consisting of p.Gly406Ser and p.Val424Phe were identified. Mutant FX proteins containing the identified amino acid substitutions were also expressed in cultured cells. These proteins were analysed by enzyme-linked immunosorbent assay and pulse-chase experiments. The results demonstrated normal intracellular synthesis and extracellular secretion of mutant FX proteins carrying the p.Val236Met, p.Arg387Cys and p.Gly406Ser amino acid substitutions. However, the results also showed that the p.Gly154Arg, p.Gly263Val and p.Val424Phe proteins were secreted less efficiently than the wild-type protein, although they were synthesized normally in the cell. Collectively, these observations suggest that the amino acid substitutions p.Gly154Arg, p.Gly263Val and p.Val424Phe induce protein misfolding, leading to the intracellular degradation of many FX proteins containing any of these mutations, and ultimately to the development of FX deficiency. On the other hand, for the p.Val236Met, p.Arg387Cys and p.Gly406Ser mutant proteins, we hypothesize that secreted FX proteins have impaired coagulant activities due to functional defects caused by these amino acid substitutions.

Genotyping of five Pakistani patients with severe inherited factor X deficiency: identification of two novel mutations.

: Congenital factor X deficiency is a rare coagulation defect characterized by variable bleeding tendency. The aim of the study was to give a first insight of F10 gene mutations in Pakistani probands. Direct sequencing and/or next-generation sequencing was performed on the coding regions, boundaries and 5' and 3' untranslated regions of the F10 gene in five severe factor X-deficient patients from Pakistan. All patients were born from consanguineous marriages and displayed FX:C levels below 2%. Sequencing revealed five different substitutions, including three previously reported p.Ala15Asp, p.Gly406Ser, and p.Gly420Arg missense variants, and also two novel variants: p.Cys57Arg and p.Gln175*. Though one genotype could not be characterized, we were able to confirm the inherited nature of the defect using familial studies. As the copy number variations were ruled out, we hypothesized the presence of deep intronic mutants that might have escaped detection from sequencing or abnormalities in epigenetic regulation. Three patients presented with severe clinical symptoms, in the early days of life, whereas two presented only with trauma-provoked bleeds and bruises later in life. Those patients with milder forms bore the p.Gly406Ser at the homozygous state and F10 unknown alleles, respectively. F10 mutation spectrum in Pakistan is heterogeneous as seen in other populations. Identification of the F10 mutations is important for genetic counseling and prenatal diagnosis in subsequent pregnancies.

Factor X heterozygous mutation in a patient with potential risk of bleeding: A case report.

RATIONALE: Factor X (FX) deficiency is a rare autosomal recessive bleeding disorder. The majority of patients carry a missense mutation in F10, and patients with bleeding disorders are either homozygous or compound heterozygous for F10. Nonsense mutations are exceptionally rare, and a heterozygous nonsense mutation is not considered to cause bleeding disorders. PATIENT CONCERNS: A 35-year-old Japanese female with an incidental hemorrhage after gynecologic polypectomy was referred to our hospital. DIAGNOSES: Following differential diagnostic workup, including cross-mixing test, congenital FX deficiency was strongly suspected. INTERVENTION: Coagulation tests and mutation analyses were conducted for the patient and her parents. OUTCOMES: Mutation analysis revealed that she carried a heterozygous nonsense mutation in F10. Pedigree analysis revealed that the mutation was inherited from her mother although there was no familial history of bleeding or hemostatic disturbance. LESSONS: Hemostatic disturbance may occur even in a patient with heterozygous F10. Because heterozygous nonsense mutation in F10 is expected to be hidden in an apparently healthy population, as observed in our patient, unexpected hemostatic disturbance may occur, particularly during the use of direct oral anticoagulant (DOAC)-targeting factor Xa for thrombotic diseases. FX activity should be evaluated before prescribing DOACs to patients.

Efficacy, safety and pharmacokinetics of a new high-purity factor X concentrate in women and girls with hereditary factor X deficiency.

Essentials Plasma-derived factor X concentrate (pdFX) is used to treat hereditary factor X deficiency. pdFX pharmacokinetics, safety and efficacy were assessed in factor X-deficient women/girls. Treatment success rate was 98%; only 6 adverse events in 2 subjects were possibly pdFX related. On-demand pdFX 25 IU kg-1 was effective and safe in women/girls with factor X deficiency. SUMMARY: Background A high-purity, plasma-derived factor X concentrate (pdFX) has been approved for the treatment of hereditary FX deficiency, an autosomal recessive disorder. Objective To perform post hoc assessments of pdFX pharmacokinetics, safety and efficacy in women and girls with hereditary FX deficiency. Patients/Methods Subjects aged ≥ 12 years with moderate/severe FX deficiency (plasma FX activity of < 5 IU dL-1 ) received on-demand or preventive pdFX (25 IU kg-1 ) for ≤ 2 years. Results Of 16 enrolled subjects, 10 women and girls (aged 14-58 years [median, 25.5 years]) received 267 pdFX infusions. Mean monthly infusions per subject were higher among women and girls (2.48) than among men and boys (1.62). In women and girls, 132 assessable bleeding episodes (61 heavy menstrual bleeds, 47 joint bleeds, 15 muscle bleeds, and nine other bleeds) were treated with pdFX, with a 98% treatment success rate versus 100% in men and boys. Mean pdFX incremental recovery was similar in the two groups (2.05 IU dL-1 versus 1.91 IU dL-1 per IU kg-1 ), as was the mean half-life (29.3 h versus 29.5 h). Of 142 adverse events in women and girls, headache was the most common (12 events in six subjects). Six events (two infusion-site erythema, two fatigue, one back pain, one infusion-site pain) in two subjects were considered to be possibly pdFX-related. Following the trial, pdFX was used to successfully maintain hemostasis in two subjects undergoing obstetric delivery. Conclusions pdFX was well tolerated and effective in women and girls with FX deficiency. Although women and girls had different bleeding symptoms and sites than men and boys, their pdFX pharmacokinetic profile was comparable.