OBJECTIVE: To explore the molecular pathogenesis for a pedigree affected with hereditary coagulation factor XII (FXII) deficiency. METHODS: Potential variant of the F12 gene was analyzed by PCR and Sanger sequencing. Expression plasmids were constructed by site-directed mutagenesis based on the wild-type and transiently transfected into 293T cells. FXII:C and FXII:Ag of the expression products were determined in the supernatant and cell lysate. Western blotting was used to verify the identify of the protein. RESULTS: Gene sequencing revealed that the proband has carried 46TT genetype and heterozygous p.Glu502Lys variants in exon 13, and a heterozygous p.Gly542Ser variant in exon 14 of the F12 gene. Transfection experiment suggested that the FXII:C and FXII:Ag of p.Glu502Lys variant in the supernatant were 28% and 24%, compared with the wild-type (100%) and FXII:Ag of cell lysates was 39% compared to the wild-type (100%). The FXII:C and FXII:Ag of p. Gly542Ser variant in the supernatant were 32% and 17% and the FXII:Ag of cell lysates was 59%. CONCLUSION The 46TT genetype, p.Glu502Lys and p.Gly542Ser variants of the F12 gene probably underlie the low FXII level in the proband. As shown by in vitro experiment, the p.Glu502Lys and p.Gly542Ser variants can both inhibit the synthesis and secrection of the FXII protein.
Exons ; Factor XII ; genetics ; Factor XII Deficiency ; genetics ; Heterozygote ; Humans ; Pedigree

OBJECTIVE: To analyze the sequence of the F12 gene and molecular mechanism for 20 patients with coagulation factor Ⅻ (FⅫ) deficiency. METHODS: The patients were selected from the outpatient department of the Second Hospital of Shanxi Medical University from July 2020 to January 2022. The activity of coagulation factor Ⅷ (FⅧ:C), factor Ⅸ (FⅨ:C), factor Ⅺ (FⅪ:C) and factor Ⅻ (FⅫ:C) were determined by using a one-stage clotting assay. All exons and 5' and 3' UTR of the F12 gene were analyzed by Sanger sequencing to detect the potential variants. Bioinformatic software was used to predict the pathogenicity of the variants, conservation of amino acids, and protein models. RESULTS: The FⅫ:C of the 20 patients has ranged from 0.07% to 20.10%, which was far below the reference values, whilst the other coagulation indexes were all normal. Sanger sequencing has identified genetic variants in 10 patients, including 4 with missense variants [c.820C>T (p.Arg274Cys), c.1561G>A (p.Glu521Lys), c.181T>C (p.Cys61Arg) and c.566.G>C (p.Cys189Ser)], 4 deletional variants c.303_304delCA(p.His101GlnfsX36), 1 insertional variant c.1093_1094insC (p.Lys365GlnfsX69) and 1 nonsense variant c.1763C>A (p.Ser588*). The remaining 10 patients only harbored the 46C/T variant. The heterozygous c.820C>T(p.Arg274Cys) missense variant in patient 1 and the homozygous c.1763C>A (p.Ser588*) nonsense variant in patient 2 were not included in the ClinVar and the Human Gene Mutation Database. Bioinformatic analysis predicted that both variants were pathogenic, and the corresponding amino acids are highly conserved. The protein prediction models suggested that the c.820C>T (p.Arg274Cys) variant may affect the stability of the secondary structure of FⅫ protein by disrupting the original hydrogen bonding force and truncating the side chain, leading to changes in the vital domain. c.1763C>A (p.Ser588*) may produce a truncated C-terminus which may alter the spatial conformation of the protein domain and affect the serine protease cleavage site, resulting in extremely reduced FⅫ:C. CONCLUSION Among individuals with low low FⅫ:C detected by one-stage clotting assay, 50% have harbored variants of the F12 gene, among which the c.820C>T and c.1763C>A were novel variants underlying the reduced coagulating factor FⅫ.
Humans ; Factor XII/genetics* ; Pedigree ; Mutation ; Mutation, Missense ; Heterozygote ; Factor XII Deficiency/genetics*

OBJECTIVE: To carry out phenotypic and genotypic analysis for two Chinese pedigrees affected with coagulation factor XII (F XII) deficiency. METHODS: Plasma prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), thrombin time (TT), and blood coagulation factor VIII, IX, XI, XII activity (FVIII:C, FIX:C, FXI:C, FXII:C) were determined with one stage clotting assay on a STAGO coagulation analyzer. FXII antigen was determined with an enzyme linked immunosorbent assay (ELISA). The 14 exons and their flanking sequences of the F12 gene were subjected to PCR amplification and Sanger sequencing. The conservation and structure of mutant protein were analyzed with MegAlign software and PYMOL software. RESULTS: The APTT of the probands was significantly prolonged, while their FXII:C and FXII:Ag were significantly reduced. Genetic analysis of the proband has revealed three novel mutations in the F12 gene, including g.5972G>A splice site mutation in intron 5, g.8810_8814delGTCTA in exon 14, and g.6259G>A (p.Pro182Leu) in exon 7. In addition, a previously known mutation IVS13-1G>A has been found. CONCLUSION Four mutations have been identified in the two Chinese pedigrees, among which three were novel. Above mutations probably played a role in the defect of FXII in the two pedigrees.
Exons ; Factor XII ; genetics ; Factor XII Deficiency ; genetics ; Genetic Testing ; Humans ; Pedigree

OBJECTIVE: To analyze the clinical phenotypes and genetic variants of a Chinese pedigree affected with Hereditary coagulation factor Ⅻ (FⅫ) deficiency. METHODS: A pedigree presented at the First Affiliated Hospital of Air Force Medical University on December 24,2021 was selected as the study subject. Activated partial thromboplastin time (APTT) and coagulation factor Ⅻ activity (FⅫ:C) were determine by a clotting method, and FⅫ antigen was detected with an ELISA assay. Following the extraction of genomic DNA, all exons and flanking regions of the F12 gene were subjected to Sanger sequencing. Clustalx-2.1-win, PROVEAN and Swiss-PDB Viewer software was used to analyze the conservation of amino acids at the variant sites, impact of of the variants on the amino acid substitutions and the protein structure. RESULTS: The APTT of the proband has prolonged to 70.2 s. Her FⅫ:C and FⅫ:Ag have decreased to 12% and 13%, respectively. DNA sequencing revealed that the proband has harbored c.346G>A (p.Gly97Ser) and c.1583C>A (p.Ser509Tyr) heterozygous compound missense variants in exons 5 and 13 of the F12 gene, respectively. Her father and sister were heterozygous carriers for the c.346G>A (p.Gly97Ser) variant, whilst her mother and brother were heterozygous for the c.1583C>A (p.Ser509Tyr) variant. CONCLUSION The c.346G>A (p.Gly97Ser) and c.1583C>A (p.Ser509Tyr) compound heterozygous variants of the F12 gene probably underlay the pathogenesis of hereditary coagulation FⅫ deficiency in this pedigree.
Humans ; Male ; Female ; Pedigree ; Factor XII/genetics* ; Mutation ; East Asian People ; Heterozygote ; Mothers ; Factor XII Deficiency/genetics*

OBJECTIVE: To explore the clinical characteristics and genetic etiology of a consanguineous Chinese pedigree affected with Congenital coagulation factor XII (XII) deficiency. METHODS: Members of the pedigree who had visited Ruian People's Hospital on July 12, 2021 were selected as the study subjects. Clinical data of the pedigree were reviewed. Peripheral venous blood samples were taken from the subjects. Blood coagulation index and genetic testing were carried out. Candidate variant was verified by Sanger sequencing and bioinformatic analysis. RESULTS: This pedigree has comprised 6 individuals from 3 generations, including the proband, his father, mother, wife, sister and son. The proband was a 51-year-old male with kidney stones. Blood coagulation test showed that his activated partial thromboplastin time (APTT) was significantly prolonged, whilst the FXII activity (FXII:C) and FXII antigen (FXII:Ag) were extremely reduced. The FXII:C and FXII:Ag of proband's father, mother, sister and son have all reduced to about half of the lower limit of reference range. Genetic testing revealed that the proband has harbored homozygous missense variant of c.1A>G (p.Arg2Tyr) of the start codon in exon 1 of the F12 gene. Sanger sequencing confirmed that his father, mother, sister and son were all heterozygous for the variant, whilst his wife was of the wild type. By bioinformatic analysis, the variant has not been included in the HGMD database. Prediction with SIFT online software suggested the variant is harmful. Simulation with Swiss-Pbd Viewer v4.0.1 software suggested that the variant has a great impact on the structure of FXII protein. Based on the Standards and Guidelines for the Interpretation of Sequence Variants: A Joint Consensus Recommendation of the American College of Medical Genetics and Genomics (ACMG), the variant was rated as likely pathogenic. CONCLUSION The c.1A>G (p.Arg2Tyr) variant of the F12 gene probably underlay the Congenital FXII deficiency in this pedigree. Above finding has further expanded the spectrum of F12 gene variants and provided a reference for clinical diagnosis and genetic counseling for this pedigree.
Male ; Female ; Humans ; Middle Aged ; Factor XII/genetics* ; Pedigree ; Codon, Initiator ; East Asian People ; Mothers ; Factor XII Deficiency/genetics* ; Mutation

OBJECTIVETo identify the genotype and pathogenesis in four Chinese pedigrees with Factor Ⅻ deficiency.

METHODSActivated partial thromboplastin time (APTT), FⅫ procoagulant activity (FⅫ∶C), FⅫ antigen（FⅫ∶Ag）and other coagulant parameters were detected. The FⅫ deficiency Pedigree members,all exons,boundary introns including the splice junctions of the FⅫ gene were amplified with Polymerase chain reaction (PCR). Expression plasmids were constructed by mutagenesis based on the wild-type and transfected into COS7 cells. FⅫ∶C and FⅫ∶Ag of the expression levels were tested in the supernatant and cell lysate.

RESULTSThe four probands presented prolonged APTT with all the values of FⅫ∶C and FⅫ∶Ag were low to 2% and 1%, respectively. There were common 46C/T polymorphism in the promoter regions of FⅫ gene in four pedigrees. Proband A was heterozygous for two mutations, g.5741-5742delCA (His101Gln) and g.7142insertC (Lys346Gln). Proband B was a heterozygous deletion mutation g.6800-6808del9bp. The results of the transfection revealed that FⅫ∶Ag in cell lysates and conditioned media protein FⅫ6800-6808del9bp were 85.6% and 51.9%. The FⅫ∶C in the conditioned media was 56.4%. Proband C was a heterozygous mutation g.8699G>A(Gly542Ser). Proband D was a homozygous mutation 8699G>A, whose parents with consanguineous marriage.

CONCLUSIONFour mutations, g.5741-5742delCA, g.7142insertC, g.6800-6808del9bp and g.8699G>A with 46C/T polymorphism in the promoter regions of FⅫ gene, were identified in the four Factor Ⅻ deficiency pedigrees. The two mutations g.5741-5742delCA and g.6800-6808del9bp were first found in China. FⅫ 6800-6808del9bp expressed in vitro suggested that almost normal proteinum synthesis but defect proteinum secretion.

Adult ; Aged ; DNA Mutational Analysis ; Factor XII ; genetics ; Factor XII Deficiency ; genetics ; Female ; Humans ; Infant ; Male ; Mutation ; Pedigree ; Polymorphism, Genetic

Adolescent ; Adult ; Aged ; Blood Coagulation ; Factor XII ; genetics ; Factor XII Deficiency ; blood ; genetics ; Female ; Humans ; Male ; Point Mutation

OBJECTIVE: To explore the laboratory phenotype and molecular pathogenesis in a Chinese pedigree affected with Hereditary coagulation factor Ⅻ (FⅫ) deficiency. METHODS: A male proband admitted to Ningbo No.2 Hospital on July 17, 2021 due to chronic gastritis and members of his pedigree (7 individuals from three generations) were selected as the study subjects. Prothrombin time (PT), activated partial thromboplastin time (APTT), FⅧ activity (FⅧ: C), FⅨ activity (FⅨ: C), FⅪ activity (FⅪ: C), FⅫ activity (FⅫ: C), and FⅫ antigen (FⅫ: Ag) were determined. All of the exons, exon-intronic boundaries, as well as the 5'- and 3'-untranslated regions of the F12 gene were subjected to Sanger sequencing. Candidate variants were verified by cloning sequencing. The effect of candidate variants on the protein function was analyzed by bioinformatics software. RESULTS: The proband, a 47-year-old male, had significantly prolonged APTT (180.0 s) and decreased FⅫ:C and FⅫ:Ag levels (< 1%). His father, mother, brother and two sons also showed certain degrees of reduction. Genetic testing revealed that the proband has harbored compound heterozygous variants of the F12 gene, namely c.1092_1093insC (p.Lys365Glnfs*69) in exon 10 and c.1792_1796delGTCTA (p.Val579Hisfs*32) in exon 14. His mother and elder son were heterozygous for the c.1092_1093ins variant, whilst his father, brother, and younger son were heterozygous for the c.1792_1796delGTCTA variant. Analysis of the promoter region of exon 1 also showed that the proband and both sons had harbored a 46T/T polymorphism, whilst other family members were 46C/T. Bioinformatic analysis suggested that the p.Val579 is a highly conserved site. Protein model analysis showed that, with the p.Val579Hisfs*32 variant, a benzene ring was added and the hydrogen bond of surrounding amino acids was changed. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.1792_1796delGTCTA was classified as a pathogenic variant (PVS1+PM2_Supporting+PM4). CONCLUSION The c.1092_1093insC (p.Lys365Glnfs*69) and c.1792_1796delGTCTA (p.Val579Hisfs*32) compound heterozygous variants of the F12 gene probably underlay the decreased FXII levels in this pedigree. Above finding has also enriched the mutational spectrum for FⅫ deficiency.
Male ; Humans ; Aged ; Middle Aged ; Pedigree ; East Asian People ; Exons ; Introns ; Family ; Factor XII Deficiency/genetics* ; 3' Untranslated Regions ; Factor XII/genetics*

OBJECTIVETo identify potential mutation underlying hereditary coagulation factor XII (FXII) deficiency in a pedigree and explore its molecular pathogenesis.

METHODSActivated partial thromboplastin time (APTT), FXII activity (FXII:C) and FXII antigen(FXII:Ag) and other coagulant parameters of the proband and 5 family members were measured. Potential mutations in the 14 exons and intron-exon boundaries of the FXII gene were screened with polymerase chain reaction (PCR) and direct DNA sequencing. Suspected mutations were confirmed with reverse sequencing. Corresponding PCR fragments from other family members were also sequenced.

RESULTSAPPT of the proband and his son were significantly prolonged to 121.5 s and 98.5 s, respectively. FXII:C and FXII:Ag of the proband and his son have reduced to 5%, 6.8% and 9%, 12.2%, respectively. Plasma plasminogen activity (PLG:A) in both individuals was slightly higher than the normal reference range. FXII:C of his second daughter and grandson were slightly reduced to 64% and 60%. FXII:C of the other family members were all in the normal range (72%-113%). A heterozygous missense mutation, g.8597G>A, was identified in exon 13 of the FXII gene in the proband, which resulted in an p.Asp538Asn substitution. For the promoter regions of the FXII gene, the genotype of the proband was 46TT. The same mutations and 46T/T were also found in the proband's son but not in other members of the family. The genotypes of the proband's spouse, eldest daughter and grandson were 46CT, and his second daughter was 46TT.

CONCLUSIONThe heterozygous mutation of g.8597G>A identified in exon 13 of FXII gene is a novel mutation. Heterozygous p.Asp538Asn mutation and 46TT in the FXII gene can cause hereditary FXII deficiency, which was probably responsible for the low FXII concentrations in this pedigree.

Adult ; Base Sequence ; Exons ; Factor XII ; genetics ; Factor XII Deficiency ; congenital ; genetics ; Female ; Genotype ; Heterozygote ; Humans ; Male ; Middle Aged ; Molecular Sequence Data ; Pedigree ; Point Mutation ; Young Adult

OBJECTIVETo analyze genetic mutation and explore its molecular pathogenesis for an hereditary coagulation factor XII(F XII) deficiency in a pedigree featuring consanguineous marriage.

METHODSActivated partial thromboplastin time (APTT), F XII procoagulant activity (F XII:C), F XII antigen (F XII:Ag) and other coagulant parameters were assayed. For the proband and his family members, exons 1-4, introns including the splice junctions of the F XII gene were amplified with polymerase chain reaction (PCR). The PCR product was purified and sequenced. The mutations were confirmed by sequencing the complimentary strand.

RESULTSThe proband has featured prolonged APTT at 157.5 s (reference range, 27.0-41.0 s). The APTT of his son has increased slightly at 48.3 s. The remaining members of the family were in normal range. F XII activity and F XII antigen of the proband were significantly decreased (<1%). The F XII activity of his wife, daughter, son and mother was also dropped to about 51%, 21%, 21% and 50%, respectively, and so was the F XII antigen (42%, 32%, 37% and 48%, respectively). Homozygous missense mutation of G→A transition at position 8699 in exon 14 resulting in Gly542Ser was identified in the proband. His mother, son and daughter were heterozygous for Gly542Ser. In the promoter regions of F XII gene, the genotype of the proband and the other members was 46T/T.

CONCLUSIONHomozygous missense mutation Gly542Ser was found in a pedigree of hereditary F XII deficiency. The homozygous missense mutation might have resulted from his parents by consanguineous marriage. Gly542Ser and 46T/T have contributed to the pathogenesis of the hereditary factor XII deficiency pedigree.

Adult ; Base Sequence ; Blood Coagulation Tests ; Consanguinity ; Exons ; Factor XII ; genetics ; Factor XII Deficiency ; blood ; genetics ; Female ; Genotype ; Humans ; Male ; Middle Aged ; Pedigree ; Polymorphism, Single Nucleotide ; Young Adult