Analysis of the Phenotype and Gene Mutations of Two Families With Combined Mutations of Anticoagulant Protein Genes.

Proband 1 had decreased protein C activity and antigen levels, with PC:A reduced to 57% and PC:Ag reduced to 59.2%.

• PC:A (protein C activity) of proband 1 was decreased to 57%
• PC:Ag (protein C antigen) of proband 1 was decreased to 59.2%
• These reductions indicate insufficient protein C levels contributing to VTE susceptibility
• Anticoagulant protein activity and antigen levels were evaluated in all family members

Proband 2 had decreased protein C activity, with PC:A reduced to 68%.

• PC:A of proband 2 was decreased to 68%
• This reduction was identified alongside SERPINC1 and PROC gene mutations
• Anticoagulant protein levels were measured as part of clinical characterization of two pedigrees

Proband 1 carried compound heterozygous mutations c.400+5G>A and c.883G>A in the SERPINC1 and PROC genes respectively.

• SERPINC1 (OMIM#:613118) and PROC (OMIM#:176860) gene analysis identified these variants in proband 1
• Mutations were identified using next-generation sequencing (NGS) and CNVplex technology
• Both mutation sites were found to be highly conserved across homologous species
• Bioinformatics analysis predicted their potential pathogenicity

Proband 2 carried compound heterozygous mutations c.811C>T and c.880C>T in the SERPINC1 and PROC genes respectively.

• SERPINC1 (OMIM#:613118) and PROC (OMIM#:176860) gene analysis identified c.811C>T and c.880C>T in proband 2
• Mutations were identified using next-generation sequencing (NGS) and CNVplex technology
• These mutation sites are highly conserved across homologous species
• Bioinformatics analysis predicts their potential pathogenicity

The identified mutations are predicted to alter the three-dimensional structures of both antithrombin (AT) and protein C (PC) proteins, thereby compromising their functional integrity.

• Bioinformatics analysis predicted pathogenicity for all identified variants
• Structural modeling suggested mutations may alter the three-dimensional structures of both AT and PC proteins
• Evolutionary conservation analysis confirmed the mutation sites are highly conserved across homologous species
• Compromised functional integrity of both proteins contributes to VTE susceptibility

Two AT mutation carriers exhibited varying degrees of elevated endogenous thrombin potential (ETP) as measured by calibrated automated thrombogram (CAT) assay.

• Thrombin generation was measured using the calibrated automated thrombogram (CAT) assay
• Both AT (antithrombin) mutation carriers showed elevated ETP, indicating a procoagulant state
• The degree of ETP elevation varied between the two AT mutation carriers
• ETP elevation reflects impaired thrombin inhibition due to AT dysfunction

In the presence of soluble thrombomodulin (sTM), two PC mutation carriers showed significantly impaired plasma anticoagulant function without a significant reduction in thrombin generation.

• CAT assay was performed in the presence of sTM to assess the protein C anticoagulant pathway
• PC mutation carriers demonstrated significantly impaired plasma anticoagulant function under sTM conditions
• No significant reduction in thrombin generation was observed in PC mutation carriers
• This pattern suggests PC pathway-specific dysfunction rather than global thrombin generation impairment

Combined mutations in SERPINC1 and PROC in both pedigrees represent two distinct mutation combinations that together confer markedly increased VTE susceptibility.

• Two pedigrees were studied, each carrying distinct combinations of SERPINC1 and PROC mutations
• AT and PC are described as key components of the anticoagulant system
• Mutations in SERPINC1 and PROC can lead to insufficient protein levels or impaired function
• The authors conclude that 'dual mutations in SERPINC1 and PROC confer markedly increased VTE susceptibility'