Dataset Information

Patients with SERPINC1 rs2227589 polymorphism found to have multiple cerebral venous sinus thromboses despite a normal antithrombin level: A case report.

ABSTRACT:

Background

The hereditary antithrombin (AT) deficiency caused by SERPINC1 gene mutation is an autosomal dominant thrombotic disorder. An increasing number of studies have shown that mutations in the SERPINC1 rs2227589 polymorphic site are correlated with a risk of venous thromboembolism (VTE) at common sites, such as lower extremity deep venous thrombosis and pulmonary thromboembolism. Currently, there are no reports of cerebral venous sinus thrombosis (CVST), a VTE site with a low incidence rate and rs2227589 polymorphism.

Case summary

Here, we report a Chinese CVST case with a mutation of the SERPINC1 rs2227589 polymorphic site, which did not cause significant AT deficiency. In a 50-year-old male patient presenting with multiple cerebral venous sinus thromboses no predisposing factors were detected, although a relative had a history of lower extremity deep venous thrombosis. We performed sequencing of the SERPINC1 gene for the patient and his daughter, which revealed the same heterozygous mutation at the rs2227589 polymorphic site: c.41+141G>A.

Conclusion

The results showed that more studies should be conducted to assess the correlation between rs2227589 polymorphism and CVST.

SUBMITTER: Liao F

PROVIDER: S-EPMC8771368 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundAntithrombin (AT) is the main physiological anticoagulant involved in hemostasis. Hereditary AT deficiency is a rare autosomal dominant thrombotic disease mainly caused by mutations in SERPINC1, which was usually manifested as venous thrombosis and pulmonary embolism. In this study, we analyzed the clinical characteristics and screened for mutant genes in two pedigrees with hereditary AT deficiency, and the functional effects of the pathogenic mutations were evaluated.MethodsCandidate gene variants were analyzed by next-generation sequencing to screen pathogenic mutations in probands, followed by segregation analysis in families by Sanger sequencing. Mutant and wild-type plasmids were constructed and transfected into HEK293T cells to observe protein expression and cellular localization of SERPINC1. The structure and function of the mutations were analyzed by bioinformatic analyses.ResultsThe proband of pedigree A with AT deficiency carried a heterozygous frameshift mutation c.1377delC (p.Asn460Thrfs*20) in SERPINC1 (NM000488.3), a 1377C base deletion in exon 7 resulting in a backward shift of the open reading frame, with termination after translation of 20 residues, and a different residue sequence translated after the frameshift. Bioinformatics analysis suggests that the missing amino acid sequence caused by the frameshift mutation might disrupt the disulfide bond between Cys279 and Cys462 and affect the structural function of the protein. This newly discovered variant is not currently included in the ClinVar and HGMD databases. p.Arg229* resulted in a premature stop codon in exon 4, and bioinformatics analysis suggests that the truncated protein structure lost its domain of interaction with factor IX (Ala414 site) after the deletion of nonsense mutations. However, considering the AT truncation protein resulting from the p.Arg229* variant loss a great proportion of the molecule, we speculate the variant may affect two functional domains HBS and RCL and lack of the corresponding function. The thrombophilia and decreased-AT-activity phenotypes of the two pedigrees were separated from their genetic variants. After lentiviral plasmid transfection into HEK293T cells, the expression level of AT protein decreased in the constructed c.1377delC mutant cells compared to that in the wild-type, which was not only reduced in c.685C > T mutant cells but also showed a significant band at 35 kDa, suggesting a truncated protein. Immunofluorescence localization showed no significant differences in protein localization before and after the mutation.ConclusionsThe p.Asn460Thrfs*20 and p.Arg229* variants of SERPINC1 were responsible for the two hereditary AT deficiency pedigrees, which led to AT deficiency by different mechanisms. The p.Asn460Thrfs*20 variant is reported for the first time.