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Background <p>Hereditary antithrombin deficiency (HATD) is a rare disease caused by mutations in the <i>SERPINC1</i> gene characterized with venous thromboembolism and/or arterial thrombotic events. We identified a proband with recurrent arterial and venous thrombosis at multiple anatomical sites and subsequently performed comprehensive thrombophilia screening and genetic analysis within the kindred.</p> Methods <p>Mutation screening of the SERPINC1 gene in the proband and family members was conducted using Sanger sequencing. Wild-type and mutant (<i>c.473T &gt; A</i>; p.Leu158Gln) <i>SERPINC1</i> expression plasmids were constructed and transiently transfected into HEK293T cells. Functional consequences of the variant were assessed through immunoblotting, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and computational structural analysis.</p> Results <p>Thrombophilia evaluation revealed significantly reduced antithrombin activity (46.2%) in the proband. Sanger sequencing identified an unreported heterozygous missense variant (<i>c.473T &gt; A</i>; p.Leu158Gln) in <i>SERPINC1</i>. Cellular studies demonstrated that this mutation reduced both the quantity and functional activity of secreted antithrombin. Immunoblot analysis indicated a slightly faster migration of the mutant protein compared to wild-type, while immunofluorescence revealed abnormal cytoplasmic aggregation. Bioinformatics analysis confirmed substitution of leucine-158 by glutamine without disruption of conserved disulfide bonds (Cys40-Cys160, Cys128-Cys182, Cys247-Cys430) or N-glycosylation sites (Asn128, Asn167, Asn187, Asn224).</p> Conclusion <p>We establish the <i>c.473T &gt; A</i> (p.Leu158Gln) variant in SERPINC1 as a pathogenic mutation underlying type I HATD, characterized by impaired secretion, cytoplasmic retention, and reduced functional activity of the mutant protein.</p>

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Clinical and functional characterization of a novel heterozygous mutation c.473T > A (p.Leu158Gln) in the SERPINC1 gene causing recurrent arteriovenous thrombophilia

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  • 发表日期：

    2025年11月20日

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  • Zhong Chongxia,
  • Guo Xuemei,
  • Xue Yanan,
  • Li Zhu,
  • Mao Kefan,
  • Zou Meijuan,
  • Yi Long,
  • Wang Yong,
  • Xu Biao,
  • Liu Yihai,
  • Kang Lina

摘要

Background

Hereditary antithrombin deficiency (HATD) is a rare disease caused by mutations in the SERPINC1 gene characterized with venous thromboembolism and/or arterial thrombotic events. We identified a proband with recurrent arterial and venous thrombosis at multiple anatomical sites and subsequently performed comprehensive thrombophilia screening and genetic analysis within the kindred.

Methods

Mutation screening of the SERPINC1 gene in the proband and family members was conducted using Sanger sequencing. Wild-type and mutant (c.473T > A; p.Leu158Gln) SERPINC1 expression plasmids were constructed and transiently transfected into HEK293T cells. Functional consequences of the variant were assessed through immunoblotting, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and computational structural analysis.

Results

Thrombophilia evaluation revealed significantly reduced antithrombin activity (46.2%) in the proband. Sanger sequencing identified an unreported heterozygous missense variant (c.473T > A; p.Leu158Gln) in SERPINC1. Cellular studies demonstrated that this mutation reduced both the quantity and functional activity of secreted antithrombin. Immunoblot analysis indicated a slightly faster migration of the mutant protein compared to wild-type, while immunofluorescence revealed abnormal cytoplasmic aggregation. Bioinformatics analysis confirmed substitution of leucine-158 by glutamine without disruption of conserved disulfide bonds (Cys40-Cys160, Cys128-Cys182, Cys247-Cys430) or N-glycosylation sites (Asn128, Asn167, Asn187, Asn224).

Conclusion

We establish the c.473T > A (p.Leu158Gln) variant in SERPINC1 as a pathogenic mutation underlying type I HATD, characterized by impaired secretion, cytoplasmic retention, and reduced functional activity of the mutant protein.