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Gemmati D, D’Aversa E, Antonica B, Grisafi M, Salvatori F, Pizzicotti S, Pellegatti P, Ciccone M, Moratelli S, Serino ML, Tisato V. Gene Dosage of F5 c.3481C>T Stop-Codon (p.R1161Ter) Switches the Clinical Phenotype from Severe Thrombosis to Recurrent Haemorrhage: Novel Hypotheses for Readthrough Strategy. Genes (Basel) 2024; 15:432. [PMID: 38674367 PMCID: PMC11050146 DOI: 10.3390/genes15040432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
Inherited defects in the genes of blood coagulation essentially express the severity of the clinical phenotype that is directly correlated to the number of mutated alleles of the candidate leader gene (e.g., heterozygote vs. homozygote) and of possible additional coinherited traits. The F5 gene, which codes for coagulation factor V (FV), plays a two-faced role in the coagulation cascade, exhibiting both procoagulant and anticoagulant functions. Thus, defects in this gene can be predisposed to either bleeding or thrombosis. A Sanger sequence analysis detected a premature stop-codon in exon 13 of the F5 gene (c.3481C>T; p.R1161Ter) in several members of a family characterised by low circulating FV levels and contrasting clinical phenotypes. The propositus, a 29 y.o. male affected by recurrent haemorrhages, was homozygous for the F5 stop-codon and for the F5 c.1691G>A (p.R506Q; FV-Leiden) inherited from the heterozygous parents, which is suggestive of combined cis-segregation. The homozygous condition of the stop-codon completely abolished the F5 gene expression in the propositus (FV:Ag < 1%; FV:C < 1%; assessed by ELISA and PT-based one-stage clotting assay respectively), removing, in turn, any chance for FV-Leiden to act as a prothrombotic molecule. His father (57 y.o.), characterised by severe recurrent venous thromboses, underwent a complete molecular thrombophilic screening, revealing a heterozygous F2 G20210A defect, while his mother (56 y.o.), who was negative for further common coagulation defects, reported fully asymptomatic anamnesis. To dissect these conflicting phenotypes, we performed the ProC®Global (Siemens Helthineers) coagulation test aimed at assessing the global pro- and anticoagulant balance of each family member, investigating the responses to the activated protein C (APC) by means of an APC-sensitivity ratio (APC-sr). The propositus had an unexpectedly poor response to APC (APC-sr: 1.09; n.v. > 2.25), and his father and mother had an APC-sr of 1.5 and 2.0, respectively. Although ProC®Global prevalently detects the anticoagulant side of FV, the exceptionally low APC-sr of the propositus and his discordant severe-moderate haemorrhagic phenotype could suggest a residual expression of mutated FV p.506QQ through a natural readthrough or possible alternative splicing mechanisms. The coagulation pathway may be physiologically rebalanced through natural and induced strategies, and the described insights might be able to track the design of novel treatment approaches and rebalancing molecules.
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Affiliation(s)
- Donato Gemmati
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
- University Strategic Centre for Studies on Gender Medicine, University of Ferrara, 44121 Ferrara, Italy
- Centre Haemostasis & Thrombosis, University of Ferrara, 44121 Ferrara, Italy
| | - Elisabetta D’Aversa
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Bianca Antonica
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Miriana Grisafi
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Francesca Salvatori
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | | | | | - Maria Ciccone
- Haematology Unit, Hospital-University of Ferrara, 44121 Ferrara, Italy
| | - Stefano Moratelli
- Centre Haemostasis & Thrombosis, University of Ferrara, 44121 Ferrara, Italy
| | - Maria Luisa Serino
- Centre Haemostasis & Thrombosis, University of Ferrara, 44121 Ferrara, Italy
| | - Veronica Tisato
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
- University Strategic Centre for Studies on Gender Medicine, University of Ferrara, 44121 Ferrara, Italy
- Laboratory of Technology for Advanced Therapies (LTTA) Centre, University of Ferrara, 44121 Ferrara, Italy
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Laboratory assessment of Activated Protein C Resistance/Factor V-Leiden and performance characteristics of a new quantitative assay. Transfus Apher Sci 2017; 56:906-913. [PMID: 29162399 DOI: 10.1016/j.transci.2017.11.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Activated Protein C Resistance is mainly associated to a factor V mutation (RQ506), which induces a deficient inactivation of activated factor V by activated protein C, and is associated to an increased risk of venous and arterial thrombosis in affected individuals, caused by the prolonged activated factor V survival. Its prevalence is mainly in Caucasians (about 5%), and this mutation is absent in Africans and Asians. Presence of Factor V-Leiden is usually evidenced with clotting methods, using a two-step APTT assay performed without or with APC: prolongation of blood coagulation time is decreased if this factor is present. The R506Q Factor V-Leiden mutation is now usually characterized using molecular biology, and this technique tends to become the first intention assay for characterization of patients. Both techniques are qualitative, and allow classifying tested individuals as heterozygotes or homozygotes for the mutation, when present. A new quantitative assay for Factor V-Leiden, using a one-step clotting method, has been developed, and designed with highly purified human coagulation proteins. Clotting is triggered with human Factor Xa, in presence of calcium and phospholipids (mixture which favours APC action over clotting process). Diluted tested plasma, is supplemented with a clotting mixture containing human fibrinogen, prothrombin, and protein S at a constant concentration. APC is added, and clotting is initiated with calcium. Calibration is performed with a pool of plasmas from patients carrying the R506Q Factor V mutation, and its mixtures with normal plasma. Homozygous patients have clotting times of about <40sec; heterozygous patients have clotting times of about 40-60sec and normal individuals yield clotting times >70sec. Factor V-Leiden concentration is usually >75% in homozygous patients, 30-60% in heterozygous patients and below 5% in normal. The assay is insensitive to clotting factor deficiencies (II, VII, VIII: C, IX, X), dicoumarol or heparin therapies, and has no interference with lupus anticoagulant (LA). This new assay for Factor V-Leiden can be easily used in any coagulation laboratory, is performed as a single test, and is quantitative. This assay has a high robustness, is accurate and presents a good intra- (<3%) and inter-assay (<5%) variability. It contributes solving most of the laboratory issues faced when testing factor V-Leiden. Quantitation of Factor V-L could contribute to a better assessment of thrombotic risk in affected patients, as this complication is first associated to and caused by the presence of a defined amount of FVa.
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Screening, Testing, or Personalized Medicine: Where do Inherited Thrombophilias Fit Best? Obstet Gynecol Clin North Am 2010; 37:87-107, Table of Contents. [DOI: 10.1016/j.ogc.2010.02.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Gessoni G, Valverde S. Clinical evaluation of a functional prothrombin time-based assay for identification of factor V Leiden carriers in a group of Italian patients with venous thrombosis. Blood Coagul Fibrinolysis 2007; 18:603-10. [PMID: 17890946 DOI: 10.1097/mbc.0b013e3282891e2f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The efficiency of a new prothrombin-based activated protein C (APC) resistance test to detect factor V Leiden (FVL) was clinically evaluated in 150 Italian patients with deep venous thrombosis. Patient samples are diluted in factor-V-deficient plasma, an APC-containing reagent, and specific factor V activator; after incubation, clotting is initiated by addition of activated-factor-FV-dependent prothrombin activator. Two prothrombin time determinations were performed under identical assay conditions except that no APC was added to one. A ratio over 4.2 for normal individuals and under 2.0 for FVL patients is expected: between 1.3 and 1.9 for FVL heterozygotes, and between 1.0 and 1.1 for FVL homozygotes. Using a predefined cut-off ratio of 2.0, a specificity and a sensitivity of 1.00 for detection of FVL mutation were found. With a cut-off ratio of 1.1, a specificity of 0.98 and a sensitivity of 1.00 were found for discrimination between FVL heterozygous (n = 60) and homozygous (n = 6). No interferences by heparins, oral contraceptives, oral anticoagulant therapy, protein C, protein S, D-dimer, homocysteine, MTHFR mutations and antiphospholipid autoantibodies were detected. In our experience, this new prothrombin time-based APC resistance assay provides improved discrimination between normal individuals and FVL carriers compared with the classical methods. Moreover, this new assay allows good discrimination between homozygous and heterozygous FVL carriers. In the authors' experience this prothrombin time-based method was not influenced by many factors compared with the classical activated partial thromboplastin time-based method.
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Affiliation(s)
- Gianluca Gessoni
- Clinical Pathology Laboratory, Ospedale Civile, Chioggia, Venice, Italy.
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Brugge JM, Simioni P, Bernardi F, Tormene D, Lunghi B, Tans G, Pagnan A, Rosing J, Castoldi E. Expression of the normal factor V allele modulates the APC resistance phenotype in heterozygous carriers of the factor V Leiden mutation. J Thromb Haemost 2005; 3:2695-702. [PMID: 16359508 DOI: 10.1111/j.1538-7836.2005.01634.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Functional defects of the protein C pathway, detectable in plasma as activated protein C (APC) resistance, are a prevalent risk factor for venous thrombosis. The factor V (FV) Leiden mutation causes APC resistance by interfering with the APC-mediated inactivation of both FVa and FVIIIa. Co-inheritance of FV Leiden and quantitative FV deficiency on different alleles, a rare condition known as pseudo-homozygous APC resistance, is associated with pronounced APC resistance and 50% reduced FV levels, because of non-expression of the non-Leiden FV allele. OBJECTIVES The role of normal FV in modulating the APC resistance phenotype in carriers of FV Leiden was investigated in patients with pseudo-homozygous APC resistance and in model systems. PATIENTS/METHODS Four functional plasma assays probing both components of APC resistance (susceptibility of FVa to APC and cofactor activity of FV in FVIIIa inactivation) were employed to compare seven clinically and genetically characterized FV Leiden pseudo-homozygotes to 30 relatives with different FV genotypes (including 12 FV Leiden heterozygotes and seven carriers of FV deficiency) and to 32 unrelated FV Leiden homozygotes. RESULTS AND CONCLUSIONS All assays consistently indicated that FV Leiden pseudo-homozygotes are significantly more APC-resistant than heterozygotes and indistinguishable from homozygotes. Thrombin generation measurements in FV-deficient plasma reconstituted with purified normal FV and FV Leiden confirmed these observations and showed that the expression of the normal FV allele is an important modulator of APC resistance in FV Leiden heterozygotes. These findings provide an explanation for the higher thrombotic risk of FV Leiden pseudo-homozygotes when compared with heterozygotes.
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Affiliation(s)
- J M Brugge
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, Netherlands
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