Analysis of two Chinese pedigrees affected with Hereditary factor V deficiency due to compound heterozygous variants of F5 gene

Factor V Leiden pseudo‐homozygotes have a more pronounced hypercoagulable state than factor V Leiden homozygotes

Objective: To analyze the gene variation of a genetic coagulation factor Ⅴ (FⅤ) deficiency pedigree and explore the molecular pathogenesis. Methods: The proband was a 32 years old female. The patient was prone to nose bleeding since childhood which was usually self-healed. On March 10, 2021, the proband went to the First Affiliated Hospital of Air Force Medical University for treatment of knee hematoma caused by a fall. None of the family members reported any history of bleeding. The prothrombin time (PT), activated partial thromboplastin time (APTT) and FⅤ activity (FⅤ: C) were detected by clotting method and the FⅤ antigen (FⅤ: Ag) was tested with enzyme-linked immunosorbent assay (ELISA). All exons and flanks of F5 gene were determined by Sanger sequencing. Clustalx-2.1-win, PolyPhen-2 and Swiss-PDBViewer software were used to analyze the conservatism of missense variation sites, whether the variations were harmful and their influences on protein structure and function. MutationTaster and NetGene2 software were used to analyze whether the splice site variation was harmful and its effect on the splice site. Results: The PT and APTT of the proband prolonged to 24.0 s and 69.8 s, respectively. The FⅤ: C and FⅤ: Ag decreased to 6% and 9%, respectively. There were compound heterozygous variations in F5 gene, which included c.911G>A heterozygous missense variation in exon 6 leading to p.Gly276Glu variation and c.5208+1G>A heterozygous missense variation in intron 15. The father and daughter had the p.Gly276Glu heterozygous variation. Her mother and son had the c.5208+1G>A heterozygous variation. Software analysis results of p.Gly276Glu heterozygous variation showed that Gly276 was conserved among homologous species, the variation was harmful, and it could affect the local structure and function of the protein. The c.5208+1G>A heterozygous variation was deleterious and resulted in the disappearance of the splice site, thereby affecting the protein function. Conclusion: The p.Gly276Glu and c.5208+1G>A compound heterozygous variants are deleterious variants associated with the patient's disease and may be the molecular pathogenesis of inherited FⅤ deficiency in this family.

Thrombin generation assay in a patient with acquired factor V inhibitor.

The C-Terminus of Tfpiα Inhibits Factor V Activation By Protecting the Arg1545 Cleavage Site

Mammalian blood has numerous essential and well-known functions, including oxygen and nutrient delivery. This elixir is recognized by blood-feeding species of mosquitos, ticks, fleas, lice, leeches, and bats that rely on blood meals for nutrition, life cycle progression, and survival. To obtain these blood meals that require minutes to a week or longer to complete,1 these blood-sucking creatures must thwart endogenous defense systems contained within blood—immune and procoagulant cells and plasma proteins that rapidly clot (within 3–4 minutes) to provide first-line defense against breaches in vascular integrity. In a fascinating display of evolutionary agility, hemovores have adapted elegant mechanisms to evade detection and to prevent blood coagulation by synthesizing an extensive armament of molecules with anesthetic, immunosuppressive, vasodilatory, anticoagulant, and profibrinolytic properties in mammals.1–3 Research characterizing the molecules generated by hemovores to bypass mammalian defense pathways has revealed exciting new mechanisms and, in some cases, novel therapeutic approaches for anticoagulation. Article see p 254 In particular, ticks have received considerable attention for their remarkable evolutionary adaptations to life as obligate hemovores. Briefly, the typical tick life cycle includes 4 stages: egg, 6-legged larva, 8-legged nymph, and adult (Figure). It takes 1 to 3 years to complete this full cycle. Ticks must consume blood at the larval, nymph, and adult stages to survive, and they die if they do not find a host. Interestingly, although neither larva nor nymphs have overt sexual differentiation, adults are fully differentiated into males and females, and compared with males, longer nymph feeding is required for the expression of female characteristics.4 Consequently, tick saliva contains multiple proteins that maintain blood fluidity to enable feeding and therefore tick survival. Figure. Life cycle of a typical tick. Larvae, nymphs, and adults require blood meals for survival and secrete anticomplement (tick salivary lectin pathway inhibitor …

Ser234Leu missense mutation in the A1 domain of factor V causing moderate factor V deficiency in a Chinese family

Severe Factor V Deficiency Caused by a Novel Compound Heterozygous Mutation: Factor V G1617V and 1-Bp Insertion

Mechanism of the Potent Activated Protein C Resistance of Novel Factor V Mutation with W1920R (FV Nara) Relative to R506Q (FV Leiden)

Novel Compound Heterozygous Factor V Deficiency with Severe Clinical Phenotype.

Effects of Multimerin 1 on Platelet and Plasma FV as Determined by Calibrated Automated Thrombography.

To screen potential mutation and explore the underlying mechanism for a consanguineous pedigree featuring hereditary coagulation factor Ⅴ (FⅤ) deficiency. Clinical diagnosis was validated by coagulant parameter assays of prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), FⅤ procoagulant activity (FⅤ:C) and FⅤ antigen (FⅤ:Ag). Potential mutations of the F5 gene in the proband and his family members were analyzed by direct DNA sequencing of PCR products of all exons, exon-intron boundaries and 3', 5' untranslated regions. Suspected mutation was confirmed by reverse sequencing. The PT and APTT in the proband were significantly prolonged, which measured 23.5 s (reference range 11.8-14.8 s) and 50.5 s (reference range 27.0-41.0 s), respectively. FⅤ activity and FⅤ antigen of the proband were significantly reduced to 8% and <1%, respectively. PT and APTT in the younger sister of the proband were also significantly prolonged (24.1 s and 62.4 s, respectively). Her FⅤ activity and FⅤ antigen were also significantly decreased (7% and <1%, respectively). PT and APTT of other family members were within the normal range. The homozygous missence mutation causing T→C transition at position 29170 in exon 5 of F5 gene has resulted in a Phe190Ser substitution in the proband. His younger sister was also homozygous for Phe190Ser. Heterozygosity for Phe190Ser was confirmed in his elder brother, elder sister, two daughters and niece, and their FⅤ activity were slightly decreased (57%, 73%, 72%, 66% and 75%, respectively). A normal wild type was observed in two younger brothers of the proband, and their FⅤ activity and FⅤ antigen were in the normal range. Homozygous missence mutation of Phe190Ser has been found in above family featuring hereditary FⅤ deficiency. The homozygous missence mutation was inherited from the parents by consanguineous marriage. Phe190Ser probably underlies may underlie the pathogenesis of hereditary FⅤ deficiency in this pedigree.

Activated protein C (APC) resistance (Dahlback et al, 1993) is a common risk factor for venous thromboembolism (Bucciarelli et al, 1999). This phenotype is highly associated with the F5 R506Q (F5 rs6025; factor V Leiden, FVL) mutation (Bertina et al, 1994). Heterozygous and homozygous discrepancies between F5 R506Q genotype and phenotype (APC resistance), known as pseudo-homozygosity, have been described (Castaman et al, 1997; Brugge et al, 2005). This incidental phenomenon suggests that, based on APC-resistance testing, there is a homozygous F5 R506Q mutation, yet, genetic testing only shows a heterozygous F5 R506Q mutation (Simioni et al, 1996). In such cases, polymorphisms located on the second factor V (FV) protein coding allele (i.e. wild-type for F5 R506Q) cause intracellular decreased FV protein production, leading to reduced FV activity (Castoldi et al, 1998). In contrast, the phenomenon “pseudo-wild-type” FVL, suggesting a wild-type F5 R506Q according to APC resistance testing but heterozygous F5 R506Q mutation by genetic testing, is infrequently described (Dargaud et al, 2003; Asselta et al, 2004). In these two studies, the polymorphisms responsible for the reduced FV protein levels were found to be located on the same FV protein coding allele, together with the F5 R506Q mutation.

Molecular Mechanism Underlying the Need for Three Cleavage Sites within the B-Domain to Activate Factor V by Thrombin

Identification and Cloning of Novel Mutations In a Compound Heterozygous Factor V Deficient Patient

Acquired factor V deficiency in a patient without evidence of a classical inhibitor