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

Clinical and functional characterization of p.Lys322stop variant in the SERPINC1 gene causing severe thrombophilia

BACKGROUND

Identification of mutations in the SERPINC1 has illuminated the intricate pathways underlying antithrombin (AT) deficiency. Our group identified a variation in the SERPINC1 gene (c.964 A > T, p.Lys322stop) and further investigated the mechanism of this variant causing AT deficiency.

METHODS

Multiple in silico tools were utilized to predict the conservation of mutations and their impact on the AT structure. The coagulation state was evaluated using the thrombin generation assay. Recombinant AT was overexpressed in HEK293T cells. Intracellular kinetics and extracellular secretion of recombinant AT-K322* were scrutinized by RT-qPCR, Western blotting, ELISA, and immunocytofluorescence.

RESULTS

Analysis of conservation in silico indicated 43 out of the 143 amino acids deleted byAT-K322* in AT were highly conserved across homologous species. In vitro expression experiments showed that there was no significant difference in mRNA levels between the mutant (AT-K322*) and wild-type (AT-WT) forms of the protein. The truncated AT-K322* protein was clearly detected in cell lysates, but not in the culture medium.

CONCLUSION

AT-K322* resulted in the generation of a truncated protein, which in turn affected the secretion of AT, ultimately leading to AT deficiency.

Do we need more guidance on thrombophilia testing? Challenges and special considerations

INTRODUCTION

Thrombophilia testing (TT) is a laboratory procedure designed to detect the risk factors involved in the pathogenesis of vascular occlusions. The role of TT is also controversial because it has a limited impact on the choice and duration of antithrombotic treatments.

AREAS COVERED

We reviewed, by examining MEDLINE up to October 2023. Accepted and not accepted thrombophilia markers are discussed along with the appropriateness or not of prescribing TT in several conditions such as: provoked and unprovoked venous thromboembolism (VTE), women who are planning a pregnancy whose relatives had VTE or have a hereditary thrombophilia, before assumption of estro-progestins, after multiple pregnant loss, arterial thrombosis, retinal vein occlusion, and splanchnic vein thrombosis.

EXPERT OPINION

TT is not essential in the management of VTE, but it may be useful for limiting adverse events in case of thrombophilia. We expose our criticism of items afforded by other guidelines by presenting our opinion based on both the scientific evidence and clinical practice. We also deal with common mistakes in prescribing and interpretations of TT hoping to purpose an educational approach on this topic. Finally, we emphasize the creation of the expert in hemostasis and thrombosis who should be present in every hospital.