Background: Antithrombin deficiency is associated with an increased risk of thromboembolism. It can be congenital, due to gene variation, or acquired, as consequence of certain clinical conditions or therapeutics. Congenital antithrombin deficiency is one of the most severe thrombophilia affecting 0,02-0,2% of the general population and exerts a dominant inheritance with incomplete penetrance and variable expression. SERPINC1 is the gene that codes for antithrombin. So far, more than 350 mutations in this gene are known to cause disease.

Aims: Report a new mutation in the SERPINC1 gene responsible for congenital antithrombin deficiency.

Methods: Collection of data in hospital clinical software.

Results: A 36-years-old woman presented with lower extremity deep vein thrombosis without apparent trigger factor. The patient reported low levels of antithrombin in previous isolated blood tests, after a DVT family study. The study we carried out after the acute phase of the disease confirmed deficiency of antithrombin, presenting low antithrombin activity values (20-30%). SERPINC1 gene mutation search was requested and identified a novel heterozygous mutation variant c.332C>T, p.(Ser111Leu). The patient underwent therapeutic anticoagulation with LMWH and fully recovered from the event after 6 months of therapeutics. Based on the results we choose to maintain prophylaxis anticoagulation indefinitely with rivaroxaban 10mg.

Conclusions: Congenital antithrombin deficiency presents with clinical heterogeneity. Genetic sequencing makes it possible to identify mutations already known or novel mutations, allowing a fully characterization of the disease that may have an impact on its management. In our case we provide genetic counseling to the patient and are currently studying her family.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/deep-vein-thrombosis-in-young-woman-reveals-a-novel-mutation-on-serpinc1-gene/