Objective:To investigate the molecular pathogenic mechanism of venous thrombosis caused by heterozygous missense mutations in two protein C (PROC) genes through laboratory phenotype analysis, genetic mutation analysis, and in vitro expression experiments.Methods:Two probands presented with venous thromboembolism at the First Affiliated Hospital of Wenzhou Medical University. Clinical data and blood samples were collected from the probands and their family members to evaluate the plasma protein C (PC) activity (PC∶A), PC antigen (PC∶Ag) levels, and other relevant coagulation parameters. The anticoagulant capacity was assessed using the thrombin generation test (TGT). The mutation sites of the PROC gene were identified using direct DNA sequencing. Bioinformatics software was used to analyze the conservation and pathogenicity of the mutated gene. PyMOL software was used for the analysis of the protein three-dimensional models and interactions between mutated amino acids. Wild-type and two mutant expression vectors were constructed and HEK293T cells were transiently transfected. Total cellular RNA was extracted from positively transfected cells to investigate the transcriptional levels of the mutant PROC gene. Enzyme-linked immunosorbent assay, Western blot, and cellular immunofluorescence assays were used to investigate the translation levels of the mutant PROC protein.Results:Probands 1 and 2 exhibited PC∶A levels of 35% and 40% and PC∶Ag levels of 44% and 39%, with increasing D-dimer levels to 4.42 mg/L and 0.83 mg/L, respectively. Meanwhile, other coagulation parameters revealed no significant abnormalities. TGT demonstrated impaired anticoagulant function in both proband witnesses and their familial PC carriers. Sequencing analysis revealed heterozygous missense mutations c. 833T>C (p. Leu278Pro) in proband 1 and c. 1330T>C (p. Trp444Arg) in proband 2 within exon 9 of the PROC gene. Conservation analysis revealed that Leu278 and Trp444 were highly conserved across homologous species. Pathogenicity analysis indicated that both p. Leu278Pro and p. Trp444Arg mutations are deleterious. Protein modeling analysis demonstrated that both mutations induce structural alterations in the protein. In vitro expression experiments revealed that compared with the wild-type, both p. Leu278Pro and p. Trp444Arg mutations showed no significant differences in the mRNA expression level of the PC protein. However, both mutations caused significantly lower PC∶Ag content and protein expression levels in the cell culture supernatant compared with the wild-type, whereas higher levels were observed in the cell culture lysate. This indicates the association of both mutations with the secretion function of the PC protein.Conclusion:The heterozygous missense mutations p. Leu278Pro and p. Trp444Arg in exon 9 of the PROC gene in both probands are associated with decreased PC levels.

OBJECTIVE: To investigate the molecular mechanism for a family with Hereditary coagulation factor Ⅻ (FⅫ) deficiency. METHODS: The proband, a 63-year-old female, was admitted to the First Affiliated Hospital of Wenzhou Medical University in August 2024 for lumbar disc herniation. Coagulation tests, including prothrombin time (PT), activated partial thromboplastin time (APTT), and FⅫ activity (FⅫ:C), were carried out for the proband and her family members (9 individuals from three generations) using a one-stage clotting assay. The level of FⅫ antigen (FⅫ:Ag) was determined with an Enzyme-linked immunosorbent assay (ELISA). Sanger sequencing was conducted to identify potential variants in the F12 gene. Multiple in silico tools were used to predict the conservation, hydrophobicity, and structural impact of the identified variants. Recombinant expression plasmids were constructed and transiently transfected into HEK293T cells. The recombinant FⅫ protein was analyzed using Western blotting (WB) and ELISA. This study was approved by the Ethics Committee of the First Affiliated Hospital of Wenzhou Medical University (Ethics No.: KY2022-R193). RESULTS: The proband showed a markedly prolonged APTT (160.3 s) and significantly decreased FⅫ:C (2%) and FⅫ:Ag (5%) levels. Analysis of the F12 gene sequence revealed a 46C/T genotype in the promoter region, a heterozygous c.1457G>A (p.Cys467Tyr) missense variant in exon 12, and a heterozygous c.1561G>A (p.Glu502Lys) missense variant in exon 13. Bioinformatic analysis showed that the p.Cys467 is highly conserved across various species, and the p.Cys467Tyr variant may affect local structural stability of the FⅫ protein. The p.Cys467Tyr variant had no effect on the transcription of the F12 gene. However, the variant has significantly decreased the FⅫ:Ag levels and FⅫ protein expression in the cell culture supernatant compared to the wild-type expression vector, while in the cell lysate, it is higher than the wild-type expression vector. In other words, the p.Cys467Tyr variant has probably caused a secretion defect of FⅫ protein. CONCLUSION The 46C/T genotype, the heterozygous p.Cys467Tyr missense variant, and the heterozygous p.Glu502Lys missense variant are associated with reduced plasma FⅫ levels in this pedigree. The p.Cys467Tyr variant, which was unreported previously, did not affect the synthesis of FⅫ but may have resulted in a secretion defect.
Humans ; Female ; Middle Aged ; Mutation, Missense ; Pedigree ; HEK293 Cells ; Male ; Factor XII/genetics* ; Adult ; Factor XII Deficiency/genetics*

Objective:To investigate the molecular pathogenic mechanism of venous thrombosis caused by heterozygous missense mutations in two protein C (PROC) genes through laboratory phenotype analysis, genetic mutation analysis, and in vitro expression experiments.Methods:Two probands presented with venous thromboembolism at the First Affiliated Hospital of Wenzhou Medical University. Clinical data and blood samples were collected from the probands and their family members to evaluate the plasma protein C (PC) activity (PC∶A), PC antigen (PC∶Ag) levels, and other relevant coagulation parameters. The anticoagulant capacity was assessed using the thrombin generation test (TGT). The mutation sites of the PROC gene were identified using direct DNA sequencing. Bioinformatics software was used to analyze the conservation and pathogenicity of the mutated gene. PyMOL software was used for the analysis of the protein three-dimensional models and interactions between mutated amino acids. Wild-type and two mutant expression vectors were constructed and HEK293T cells were transiently transfected. Total cellular RNA was extracted from positively transfected cells to investigate the transcriptional levels of the mutant PROC gene. Enzyme-linked immunosorbent assay, Western blot, and cellular immunofluorescence assays were used to investigate the translation levels of the mutant PROC protein.Results:Probands 1 and 2 exhibited PC∶A levels of 35% and 40% and PC∶Ag levels of 44% and 39%, with increasing D-dimer levels to 4.42 mg/L and 0.83 mg/L, respectively. Meanwhile, other coagulation parameters revealed no significant abnormalities. TGT demonstrated impaired anticoagulant function in both proband witnesses and their familial PC carriers. Sequencing analysis revealed heterozygous missense mutations c. 833T>C (p. Leu278Pro) in proband 1 and c. 1330T>C (p. Trp444Arg) in proband 2 within exon 9 of the PROC gene. Conservation analysis revealed that Leu278 and Trp444 were highly conserved across homologous species. Pathogenicity analysis indicated that both p. Leu278Pro and p. Trp444Arg mutations are deleterious. Protein modeling analysis demonstrated that both mutations induce structural alterations in the protein. In vitro expression experiments revealed that compared with the wild-type, both p. Leu278Pro and p. Trp444Arg mutations showed no significant differences in the mRNA expression level of the PC protein. However, both mutations caused significantly lower PC∶Ag content and protein expression levels in the cell culture supernatant compared with the wild-type, whereas higher levels were observed in the cell culture lysate. This indicates the association of both mutations with the secretion function of the PC protein.Conclusion:The heterozygous missense mutations p. Leu278Pro and p. Trp444Arg in exon 9 of the PROC gene in both probands are associated with decreased PC levels.

Objective:This study aimed to primarily discuss the pathogenesis of hereditary coagulation factor Ⅴ (FⅤ) deficiency in a family with a consanguineous cousin marriage.Methods:The coagulation indices of the pedigree (three generations with seven individuals) and the thrombin levels of the proband and his father were assessed. All exons of the F5 gene were analyzed with Sanger sequencing, and a new mutation was confirmed with reverse sequencing. The corresponding sites of the family members were then determined. A set of online software was utilized to predict the conservation and pathogenicity of the mutation site. The pathogenicity of this mutation site was evaluated according to the American College of Medical Genetics and Genomics (ACMG) guidelines.Results:The prothrombin time (PT) and activated partial thromboplastin time (APTT) of the proband were 52.2 s and 108.3 s, respectively. FⅤ activity (FⅤ∶ C) and FⅤ antigen (FⅤ∶Ag) were greatly decreased by 2% and 4%, respectively. The problem was diagnosed as type Ⅰ F Ⅴ deficiency. PT and APTT of the proband’s father, mother, and grandfather were slightly higher than the upper limit of the reference range, and FⅤ∶C and FⅤ∶Ag were approximately 50% of normal. The thromboplastin generation assay revealed that the amount of thromboplastin produced by the proband and his father was lower than that of the healthy controls and that the proband’s ability to produce thromboplastin was more severely impaired. Sequencing analysis revealed that the proband demonstrated a homozygous missense mutation of c.5128T > C (p.Trp1682Arg) in exon 15 of the F5 gene. The grandfather, father, and mother of the proband were all heterozygous for c.5128 T > C. Conservative analysis revealed that p.Trp1682 was a highly conserved site in the homozygous species, and five online software programs, including Mutation Taster, SIFT, REVEL, PolyPhen-2, and CADD, indicated that the mutation was pathogenic. The ACMG guidelines recommend that the new mutation c.5128 T > C is a possible pathogenic mutation (PM2 + PM3 + PP1 + PP3 + PP4). The comparison of the protein models before and after the mutation revealed that the benzene ring and the hydrogen bond were reduced after the mutation, which changed the local structure of the F Ⅴ protein.Conclusion:The missense mutation c.5128T > C (p. Trp1682Arg) in exon 15 of the F5 gene was initially considered the genetic cause of the FⅤ deficiency family. This mutation is the first report globally, which further enriches the gene-phenotype spectrum of FⅤ deficiency.

A 34 year old female patient was scheduled to undergo surgical resection due to a "breast nodule". Preoperative examination revealed an activated partial thromboplastin time (APTT) of 66.2 seconds, coagulation factor Ⅺ activity (FⅪ: C) of 2%, and FⅪ antigen (FⅪ: Ag) of 40.3%. The patient and family members showed no abnormal bleeding symptoms. Diagnosed as hereditary coagulation factor Ⅺ deficiency. Genetic testing revealed that the F11 gene had a heterozygous nonsense mutation in exon 10, c.1107C>A (p.Tyr351stop), and a heterozygous missense mutation in exon 13, c.1562A>G (p.Tyr503Cys). The father and son were p Heterozygous carriers of Tyr351stop mutation, while the mother and daughter are p Heterozygous carriers of Tyr503Cys mutations. The in vitro expression results showed that p The Tyr351stop mutation resulted in a significant decrease in the transcription level of F11 gene, while p The Tyr503Cys mutation has no effect on the transcription level and protein expression level of F11 gene, but it leads to a significant decrease in the level of FⅪ:C in the cell culture supernatant.

Objective:Molecular mechanisms underlying compound heterozygous mutations in a patient with inherited antithrombin (AT) deficiency.Methods:The proband was admitted to the First Affiliated Hospital of Wenzhou Medical University in November 2018 with a one-day history of sudden syncope and limb twitching. Peripheral venous blood was collected from the proband and members of his lineages, totaling nine persons across three generations, and a family lineage survey was conducted. AT activity (AT:A) was measured using a chromogenic substrate assay, while AT antigen (AT:Ag) was detected through an immunoturbidimetric assay. Mutation sites were identified by means of Sanger sequencing of the SERPINC1 gene, and silico tools were applied to predict the mutational conservation and hydrophobicity changes. Recombinant plasmid expression vectors were constructed and transfected into HEK293T cells for in vitro overexpression studies. The recombinant AT protein was characterized using Western Blotting, ELISA, and cellular immunofluorescence assays.Results:The proband was a 21-year-old man with type Ⅰ AT deficiency. His AT:A was 33%, along with a corresponding reduction in AT:Ag. The genetic analysis revealed there was a heterozygous insertion mutation at c.318_319insT (p.Asn107*) and a heterozygous missense mutation at c.922G>T (p.Gly308Cys) in exons 2 and 5, respectively. These mutation sites were entirely conserved among the homologous species. Additionally, hydrophobicity studies showed that the p.Gly308Cys mutation will decrease the hydrophilicity of amino acid residues 307-313. The in vitro expression studies indicated a reduction of approximately 46.98%±2.94% and 41.35%±1.48% in the amount of recombinant protein AT-G308C in transfected cell lysates and culture supernatants, respectively. Treatment with the proteasome inhibitor (MG132) restored the cytoplasmic levels of AT-G308C protein to a level similar to that of wild-type protein. However, neither cell lysate nor culture supernatant demonstrated the presence of the recombinant protein AT-N107*. Conclusions:The heterozygous insertion mutation of p.Asn107* and the heterozygous missense mutation of p.Gly308Cys have been associated with reduced AT levels in proband. The p.Asn107* heterozygous insertion mutation may initiate the degradation of mRNA via nonsense mutation-mediated mechanisms, which would remove the defective transcripts, as well as the p.The Gly308Cys heterozygous missense mutation may cause the AT protein to undergo proteasome-dependent degradation by modifying the hydrophobicity of nearby residues in the cytoplasm.

Objective:This study aimed to primarily discuss the pathogenesis of hereditary coagulation factor Ⅴ (FⅤ) deficiency in a family with a consanguineous cousin marriage.Methods:The coagulation indices of the pedigree (three generations with seven individuals) and the thrombin levels of the proband and his father were assessed. All exons of the F5 gene were analyzed with Sanger sequencing, and a new mutation was confirmed with reverse sequencing. The corresponding sites of the family members were then determined. A set of online software was utilized to predict the conservation and pathogenicity of the mutation site. The pathogenicity of this mutation site was evaluated according to the American College of Medical Genetics and Genomics (ACMG) guidelines.Results:The prothrombin time (PT) and activated partial thromboplastin time (APTT) of the proband were 52.2 s and 108.3 s, respectively. FⅤ activity (FⅤ∶ C) and FⅤ antigen (FⅤ∶Ag) were greatly decreased by 2% and 4%, respectively. The problem was diagnosed as type Ⅰ F Ⅴ deficiency. PT and APTT of the proband’s father, mother, and grandfather were slightly higher than the upper limit of the reference range, and FⅤ∶C and FⅤ∶Ag were approximately 50% of normal. The thromboplastin generation assay revealed that the amount of thromboplastin produced by the proband and his father was lower than that of the healthy controls and that the proband’s ability to produce thromboplastin was more severely impaired. Sequencing analysis revealed that the proband demonstrated a homozygous missense mutation of c.5128T > C (p.Trp1682Arg) in exon 15 of the F5 gene. The grandfather, father, and mother of the proband were all heterozygous for c.5128 T > C. Conservative analysis revealed that p.Trp1682 was a highly conserved site in the homozygous species, and five online software programs, including Mutation Taster, SIFT, REVEL, PolyPhen-2, and CADD, indicated that the mutation was pathogenic. The ACMG guidelines recommend that the new mutation c.5128 T > C is a possible pathogenic mutation (PM2 + PM3 + PP1 + PP3 + PP4). The comparison of the protein models before and after the mutation revealed that the benzene ring and the hydrogen bond were reduced after the mutation, which changed the local structure of the F Ⅴ protein.Conclusion:The missense mutation c.5128T > C (p. Trp1682Arg) in exon 15 of the F5 gene was initially considered the genetic cause of the FⅤ deficiency family. This mutation is the first report globally, which further enriches the gene-phenotype spectrum of FⅤ deficiency.