Identification and characterization of two SERPINC1 mutations causing congenital antithrombin deficiency

Genetic factors, risk prediction and AI application of thrombotic diseases

In thrombotic diseases, coagulation, anticoagulation, and fibrinolysis are three key physiological processes that interact to maintain blood in an appropriate state within blood vessels. When these processes become imbalanced, such as excessive coagulation or reduced anticoagulant function, it can lead to the formation of blood clots. Genetic factors play a significant role in the onset of thrombotic diseases and exhibit regional and ethnic variations. The decision of whether to initiate prophylactic anticoagulant therapy is a matter that clinicians must carefully consider, leading to the development of various thrombotic risk assessment scales in clinical practice. Given the considerable heterogeneity in clinical diagnosis and treatment, researchers are exploring the application of artificial intelligence in medicine, including disease prediction, diagnosis, treatment, prevention, and patient management. This paper reviews the research progress on various genetic factors involved in thrombotic diseases, analyzes the advantages and disadvantages of commonly used thrombotic risk assessment scales and the characteristics of ideal scoring scales, and explores the application of artificial intelligence in the medical field, along with its future prospects.

In vivo LNP-CRISPR Approaches for the Treatment of Hemophilia

Hemophilia is a genetic disorder that is caused by mutations in coagulation factor VIII (hemophilia A) or IX (hemophilia B) genes resulting in blood clotting disorders. Despite advances in therapies, such as recombinant proteins and products with extended half-lives, the treatment of hemophilia still faces two major limitations: the short duration of therapeutic effect and production of neutralizing antibodies against clotting factors (inhibitor). To overcome these limitations, new hemophilia treatment strategies have been established such as gene therapy, bispecific antibody, and rebalancing therapy. Although these strategies have shown promising results, it is difficult to achieve a permanent therapeutic effect. Advances in the clustered regularly interspaced short palindromic repeat (CRISPR) technology have allowed sustainable treatment by correcting mutated genes. Since genome editing generates irreversible changes in host genome, safety must be ensured by delivering target organs. Therefore, the delivery tool of the CRISPR system is crucial for safe, accurate, and efficient genome editing. Recently, non-viral vector lipid nanoparticles (LNPs) have emerged as safer tools for delivering CRISPR systems than other viral vectors. Several previous hemophilia pre-clinical studies using LNP-CRISPR showed that sufficient and sustainable therapeutic effects, which means that LNP-CRISPR-mediated genome-editing therapy can be a valid option for the treatment of hemophilia. In this paper, we summarize the latest advancements in the successful treatment of hemophilia and the potential of CRISPR-mediated genome-editing therapy using LNPs.

Clinical and functional characterization of rare compound heterozygous mutations in the SERPINC1 gene causing severe thrombophilia

INTRODUCTION

Hereditary antithrombin (AT) deficiency is a rare autosomal dominant disorder with significant clinical heterogeneity. In the study, we identified a patient with AT deficiency caused by compound heterozygous mutations in the SERPINC1 gene.

METHODS

A total of 9 individuals from three generations were investigated. The mutations were identified by direct sequencing of SERPINC1. Multiple in silico tools were programmed to predict the conservation of mutations and the effect on the AT structure. The coagulation state was evaluated by the thrombin generation assay. Recombinant AT was overexpressed in HEK293T cells; the mRNA level was determined using RT-qPCR. Western blotting, ELISA, and immunocytofluorescence were applied to characterize the recombinant AT protein.

RESULTS

The proband was a 26-year-old male who experienced recurrent venous thrombosis. He presented the type I deficiency with 33 % AT activity and a synchronized decrease in AT antigen. Genetic screening revealed that he carried a heterozygous c.318_319insT (p.Asn107*) in exon 2 and a heterozygous c.922G > T (p.Gly308Cys) in exon 5, both of which were completely conserved in homologous species and resulted in enhanced thrombin generation capability. Hydrophobicity analysis suggested that the p.Gly308Cys mutation may interfere with the hydrophobic state of residues 307-313. In vitro expression studies indicated that the levels of the recombinant protein AT-G308C decreased to 46.98 % ± 2.94 % and 41.35 % ± 1.48 % in transfected cell lysates and media, respectively. After treatment with a proteasome inhibitor (MG132), the quantity of AT-G308C protein in the cytoplasm was replenished to a level comparable to that of the wild type. The mRNA level of AT-N107* was significantly reduced and the recombinant protein AT-N107* was not detected in either the lysate or the culture media.

CONCLUSION

These two mutations were responsible for the AT defects and clinical phenotypes of the proband. The p.Gly308Cys mutation could lead to proteasome-dependent degradation of the AT protein in the cytoplasm by altering local residue hydrophobicity. The c.318_319insT could eliminate aberrant transcripts by triggering nonsense-mediated mRNA degradation. Both mutations resulted in type I AT deficiency.

Perioperative management of venous recanalization in a patient with inherited antithrombin deficiency: case report

Background

Inherited antithrombin (AT) deficiency (ATD) is a severe thrombophilia causing venous thromboembolism, which can be complicated by postthrombotic syndrome (PTS). Venous recanalization, used to treat PTS, often requires a temporary withdrawal of anticoagulant therapy. In ATD patients, there is a risk of insufficient perioperative anticoagulation due to altered heparin response.

Key Clinical Question

There is no consensus on how to manage perioperative anticoagulation in ATD patients.

Clinical Approach

Warfarin-unfractionated heparin transition could be a more reliable strategy than low-molecular-weight heparin transition because unfractionated heparin anti-Xa activity not only reflects heparin-bound AT but also AT's activity, which correlates strongly with therapeutic anticoagulation. Biological monitoring could thus decrease the number of plasma-derived AT supplementation.

Conclusion

This study describes a successful perioperative management of anticoagulation for venous recanalization that could be suggested to type 1 ATD patients with PTS.

Multiple venous thromboembolisms in a pregnant patient carrying a novel mutation in SERPINC1 (p.M313T) that causes a transient antithrombin deficiency: a case report

BACKGROUND

Congenital antithrombin deficiency is an autosomal dominant disease that results in deep venous thrombosis and pulmonary embolism, which is mainly caused by mutations in the antithrombin gene (SERPINC1). Since SERPINC1 is highly susceptible to alterations, severe structural and functional changes that promote thrombosis may occur. Clinical presentations vary from different alterations. We report a pregnant case with novel mutation in SERPINC1 presenting transient antithrombin deficiency and multiple venous thromboembolisms.

CASE PRESENTATION

We report a case of a 36-year-old pregnant patient who was diagnosed with congenital antithrombin deficiency for carrying a novel heterozygous mutation, NM_000488:exon5:c.T9 38 C:p. M313T in SERPINC1 presenting transient antithrombin deficiency and multiple venous thromboembolisms. Thrombolytic with alteplase and anticoagulant therapies with low-molecular-weight heparin and warfarin were administrated. After confirming the genetic analysis and the termination of pregnancy, rivaroxaban was administrated, and the thrombosis reduced.

CONCLUSIONS

Our study enriched the mutation database of SERPINC1 gene, provided some new theoretical basis for gene diagnosis and genetic counseling of patients with transient antithrombin deficiency. While it still needs for subsequent exploration of molecular pathogenesis.

Human induced pluripotent stem cells derived from a patient with a mutation of SERPINC1 c.236G>A (p.R79H)

Mutation of SERPINC1 is related to the incidence of Inherited antithrombin (AT) deficiency. In this study, we generated a human induced pluripotent stem cell (iPSC) line from peripheral blood mononuclear cells of a patient with a mutation of SERPINC1 c.236G>A (p.R79H). The generated iPSCs express pluripotent cell markers with no mycoplasma contamination. Besides, it has a normal female karyotype and could differentiate into all three germ layers in vitro.

Antithrombin Therapy: Current State and Future Outlook

Antithrombin (AT) is a natural anticoagulant pivotal in inactivating serine protease enzymes in the coagulation cascade, making it a potent inhibitor of blood clot formation. AT also possesses anti-inflammatory properties by influencing anticoagulation and directly interacting with endothelial cells. Hereditary AT deficiency is one of the most severe inherited thrombophilias, with up to 85% lifetime risk of venous thromboembolism. Acquired AT deficiency arises during heparin therapy or states of hypercoagulability like sepsis and premature infancy. Optimization of AT levels in individuals with AT deficiency is an important treatment consideration, particularly during high-risk situations such as surgery, trauma, pregnancy, and postpartum. Here, we integrate the existing evidence surrounding the approved uses of AT therapy, as well as potential additional patient populations where AT therapy has been considered by the medical community, including any available consensus statements and guidelines. We also describe current knowledge regarding cost-effectiveness of AT concentrate in different contexts. Future work should seek to identify specific patient populations for whom targeted AT therapy is likely to provide the strongest clinical benefit.