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Sacco M, Testa MF, Ferretti A, Basso M, Lancellotti S, Tardugno M, Di Gennaro L, Concolino P, Minucci A, Spoliti C, Branchini A, De Cristofaro R. An integrated multitool analysis contributes elements to interpreting unclassified factor IX missense variants associated with hemophilia B. J Thromb Haemost 2024:S1538-7836(24)00425-2. [PMID: 39019441 DOI: 10.1016/j.jtha.2024.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 06/10/2024] [Accepted: 07/05/2024] [Indexed: 07/19/2024]
Abstract
BACKGROUND Dissection of genotype-phenotype relationships in hemophilia B (HB) is particularly relevant for challenging (mild HB) or for HB-associated but unclassified factor (F)IX missense variants. OBJECTIVE To contribute elements to interpret unclassified HB-associated FIX missense variants by a multiple-level approach upon identification of a reported, but uncharacterized, FIX missense variant associated with mild HB. METHODS Molecular modeling of wild-type and V92A FIX variants, expression studies in HEK293 cells with evaluation of protein (ELISA, western blotting) and activity (activated partial thromboplastin time-based/chromogenic assays) levels after recombinant expression, and multiple prediction tools. RESULTS The F9(NM_000133.4):c.275T>C (p.V92A) variant was found in a mild HB patient (antigen, 45.4 U/dL; coagulant activity, 23.6 IU/dL; specific activity, 0.52). Newly generated molecular models showed alterations in Gla/EGF1-EGF2 domain conformation impacting Ca++ affinity and protein-protein interactions with activated factor XI (FXIa). Multitool analysis indicated a moderate impact on protein structure/function of the valine-to-alanine substitution, in accordance with patient and modeling data. Expression studies on the V92A variant showed a specific activity (0.49 ± 0.07; wild-type, 1.0 ± 0.1) recapitulating that of the natural variant, and pointed toward a moderate activation impairment as the main determinant underlying the p.V92A defect. The validated multitool approach, integrated with evidence-based data, was challenged on a panel (n = 9) of unclassified FIX missense variants, which resulted in inferred protein (secretion/function) outputs and HB severity. CONCLUSION The rational integration of multitool and multiparameter analyses contributed elements to interpret genotype/phenotype relationships of unclassified FIX missense variants, with implications for diagnosis, management, and treatment of HB patients, and potentially translatable into other human disorders.
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Affiliation(s)
- Monica Sacco
- Department of Translational Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
| | - Maria Francesca Testa
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Antonietta Ferretti
- Center for Hemorrhagic and Thrombotic Diseases, Foundation University Hospital "A. Gemelli" IRCCS, Rome, Italy
| | - Maria Basso
- Center for Hemorrhagic and Thrombotic Diseases, Foundation University Hospital "A. Gemelli" IRCCS, Rome, Italy
| | - Stefano Lancellotti
- Center for Hemorrhagic and Thrombotic Diseases, Foundation University Hospital "A. Gemelli" IRCCS, Rome, Italy
| | - Maira Tardugno
- Department of Translational Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
| | - Leonardo Di Gennaro
- Center for Hemorrhagic and Thrombotic Diseases, Foundation University Hospital "A. Gemelli" IRCCS, Rome, Italy
| | - Paola Concolino
- Molecular and Genomic Diagnostics Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
| | - Angelo Minucci
- Molecular and Genomic Diagnostics Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy
| | - Claudia Spoliti
- Department of Translational Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy.
| | - Raimondo De Cristofaro
- Department of Translational Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy; Center for Hemorrhagic and Thrombotic Diseases, Foundation University Hospital "A. Gemelli" IRCCS, Rome, Italy.
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Todaro AM, Radu CM, Ciccone M, Toffanin S, Serino ML, Campello E, Bulato C, Lunghi B, Gemmati D, Cuneo A, Hackeng TM, Simioni P, Bernardi F, Castoldi E. In vitro and ex vivo rescue of a nonsense mutation responsible for severe coagulation factor V deficiency. J Thromb Haemost 2024; 22:410-422. [PMID: 37866515 DOI: 10.1016/j.jtha.2023.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/24/2023]
Abstract
BACKGROUND Coagulation factor V (FV) deficiency is a rare bleeding disorder that is usually managed with fresh-frozen plasma. Patients with nonsense mutations may respond to treatment with readthrough agents. OBJECTIVES To investigate whether the F5 p.Arg1161Ter mutation, causing severe FV deficiency in several patients, would be amenable to readthrough therapy. METHODS F5 mRNA and protein expression were evaluated in a F5 p.Arg1161Ter-homozygous patient. Five readthrough agents with different mechanisms of action, i.e. G418, ELX-02, PTC-124, 2,6-diaminopurine (2,6-DAP), and Amlexanox, were tested in in vitro and ex vivo models of the mutation. RESULTS The F5 p.Arg1161Ter-homozygous patient showed residual F5 mRNA and functional platelet FV, indicating detectable levels of natural readthrough. COS-1 cells transfected with the FV-Arg1161Ter cDNA expressed 0.7% FV activity compared to wild-type. Treatment with 0-500 μM G418, ELX-02, and 2,6-DAP dose-dependently increased FV activity up to 7.0-fold, 3.1-fold, and 10.8-fold, respectively, whereas PTC-124 and Amlexanox (alone or in combination) were ineffective. These findings were confirmed by thrombin generation assays in FV-depleted plasma reconstituted with conditioned media of treated cells. All compounds except ELX-02 showed some degree of cytotoxicity. Ex vivo differentiated megakaryocytes of the F5 p.Arg1161Ter-homozygous patient, which were negative at FV immunostaining, turned positive after treatment with all 5 readthrough agents. Notably, they were also able to internalize mutant FV rescued with G418 or 2,6-DAP, which would be required to maintain the crucial platelet FV pool in vivo. CONCLUSION These findings provide in vitro and ex vivo proof-of-principle for readthrough-mediated rescue of the F5 p.Arg1161Ter mutation.
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Affiliation(s)
- Alice M Todaro
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Claudia M Radu
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Maria Ciccone
- Department of Medical Sciences, Section of Haematology, Sant'Anna Hospital, Ferrara University, Ferrara, Italy
| | - Serena Toffanin
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - M Luisa Serino
- Department of Medical Sciences, Section of Haematology, Sant'Anna Hospital, Ferrara University, Ferrara, Italy
| | - Elena Campello
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Cristiana Bulato
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Barbara Lunghi
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, Ferrara University, Ferrara, Italy
| | - Donato Gemmati
- Department of Translational Medicine, Haemostasis & Thrombosis Centre, Ferrara University, Ferrara, Italy
| | - Antonio Cuneo
- Department of Medical Sciences, Section of Haematology, Sant'Anna Hospital, Ferrara University, Ferrara, Italy
| | - Tilman M Hackeng
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Paolo Simioni
- Department of Medicine, Thrombotic and Haemorrhagic Diseases Unit, Padua University Medical School, Padua, Italy
| | - Francesco Bernardi
- Department of Life Sciences and Biotechnology, Section of Biochemistry and Molecular Biology, Ferrara University, Ferrara, Italy
| | - Elisabetta Castoldi
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
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Li F, He L, Chen G, Lu Y, Li R, Zhang Y, Jing X, Ling R, Li D, Liao C. Variant spectrum of F8 and F9 in hemophilia patients from southern China and 26 novel variants. Front Genet 2023; 14:1254265. [PMID: 38196513 PMCID: PMC10775173 DOI: 10.3389/fgene.2023.1254265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 12/11/2023] [Indexed: 01/11/2024] Open
Abstract
Hemophilia, an X-linked recessive disorder, is characterized by spontaneous or trauma-induced prolonged bleeding. It is classified as hemophilia A when caused by variants in the F8 gene, and hemophilia B when caused by F9 variants. Few studies have described hemophilia variants in the Chinese population. This study aimed to investigate the clinical and genetic profiles of 193 hemophilia patients from southern China. Utilizing Sanger sequencing, multiplex ligation-dependent probe amplification, gap detection, long-range PCR, and multiplex PCR, we identified both F8 and F9 gene variants. Pregnant women with a history of hemophilia A offspring underwent amniocentesis or villus sampling for the variant detection. Variants in F8 and F9 were pinpointed in 183 patients, with 26 being novel discoveries. Notably, genetic testing was absent in the initial evaluation of 133 out of 161 patients, leading to a protracted average definitive diagnosis timeline of 2 years. Remarkably, two hemophilia A cases with anticipated severe phenotypes due to protein-truncating variants presented with only moderate or mild clinical manifestations. Among the 40 fetuses tested, 34 were males, with 17 exhibiting hemizygous variants in the F8 gene. Our results contribute to the broader understanding of F8 and F9 variant spectrum and highlight the underuse of genetic analyses in southern China.
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Affiliation(s)
- Fucheng Li
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Liya He
- Hematology Department, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Guilan Chen
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Yan Lu
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Ru Li
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Yongling Zhang
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Xiangyi Jing
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Rujuan Ling
- Department of Internal Medicine, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Dongzhi Li
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Can Liao
- Department of Prenatal Diagnostic Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
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