Practical guideline for major hereditary thrombophilia

Main text

Thrombophilia encompasses a spectrum of disorders characterized by a predisposition to a hypercoagulable state, frequently culminating in thromboembolism.¹ Among these, hereditary thrombophilia is defined as conditions arising from genetic mutations that disrupt hemostatic equilibrium. The clinical manifestations of thrombophilia primarily involve venous thromboembolism (VTE). Certain genetic variants may also predispose individuals to arterial thrombotic events.

While previous articles have provided guidance on indications for thrombophilia screening, discussions are largely confined to whether such screening informs the “duration of anticoagulation therapy.”¹ This guideline, focusing specifically on hereditary thrombophilia, seeks to delineate the impact of diverse genetic factors on the selection of anticoagulant drug types and their duration. This work primarily addresses major hereditary thrombophilias. Gene polymorphisms with minimal contributions to disease, such as those associated with the ABO blood group, as well as exceedingly rare genetic mutations like F9 Padua, are not discussed here due to their limited clinical relevance or scant supporting evidence. The panel adopts the 2011 Oxford Center for Evidence-Based Medicine framework to assess the level of evidence (LoE) and make recommendations.

Indications for suspected thrombophilia

Recommendation (Figure 1): screening for thrombophilia is suggested under the following circumstances (LoE 4): (1) VTE at a young age, usually considered to be less than 50 years, particularly in the absence of strong provoking factors such as active malignancy, major surgery, or systemic vasculitis; (2) ischemic stroke or myocardial infarction at a young age, usually considered to be less than 40 years, especially in the absence of atherosclerotic risk factors; (3) neonatal purpura fulminans; (4) VTE at atypical sites, including cerebral, portal, mesenteric, or splenic veins; (5) multisite VTE during a single thrombotic event; (6) recurrent VTE without regional anatomic abnormalities; (7) poor response or progression of thrombosis during standard antithrombotic therapy; (8) warfarin-induced skin necrosis; and (9) VTE with a family history of thrombosis or diagnosed thrombophilia.

Figure 1.

Management of major hereditary thrombophilia

Although thrombophilia screening does not aid in determining the duration of anticoagulation for patients who have been planned for prolonged anticoagulation, it provides other practical clinical value. Identifying specific thrombophilias enables tailored anticoagulant drug selection, refines VTE risk assessment during hospitalization, and promotes awareness of preventive measures. In China, the prevalence of hereditary antithrombin (AT) deficiency and F2 gain-of-function mutations in unprovoked VTE cases is approximately 11.2% and 3.5%, respectively.² These mutations often result in heparin and/or antithrombin resistance. Furthermore, the prevalence of hereditary deficiencies in protein C (PC) and protein S (PS) is approximately 22.2% and 18.7%, respectively.² These are associated with an elevated risk of warfarin-induced skin necrosis. The identification of pathogenic genetic mutations also fosters advancements in gene therapy. While such therapies remain under investigation, their development underscores the clinical significance of precise genetic characterization.³

Diagnostic evaluation of major hereditary thrombophilia

Recommendations (Figure 1): the following tests are suggested for diagnosing hereditary thrombophilia (LoE 4): (1) PC activity assays and PROC1 gene analysis; (2) free PS antigen testing and PROS1 gene analysis; (3) AT activity assays and SERPINC1 gene analysis, noting that rare mutations in PMM2, MPI, or ALG12 may also be implicated; (4) factor V Leiden genotyping; (5) prothrombin G20210A mutation analysis; and (6) F2 Arg541 and Arg596 mutations analysis.

To minimize the confounding effects of acquired factors on anticoagulant protein levels, repeat testing is recommended after a 3-month interval. Quantitative antigen assays serve as diagnostic tools for deficiency subtyping. Genetic testing, complementing functional activity assays, enhances the sensitivity of detecting underlying hereditary anomalies. Key methodologies for genetic testing include Sanger sequencing and next-generation sequencing via targeted gene panels.² For identifying large structural variants or copy-number alterations, multiplex ligation-dependent probe amplification, or third-generation sequencing are recommended.

Anticoagulation therapy and secondary thromboprophylaxis

Recommendation (Figure 1):

• (1)Heterozygous PC deficiency: for anticoagulation of an acute thrombotic event, the use of full-dose low-molecular-weight heparins (LMWHs) or direct oral anticoagulants (DOACs) is suggested. In refractory thrombosis or severe complications, such as warfarin-induced skin necrosis, purpura fulminans, or disseminated intravascular coagulation (DIC), PC concentrates are indicated. For secondary prevention, indefinite anticoagulation with a prophylactic dose of DOACs is suggested, alongside regular follow-up. Dose-adjusted warfarin remains a second-line option (LoE 4).
• (2)Heterozygous PS deficiency: similar to PC deficiency, using full-dose LMWHs or DOACs is suggested for the treatment of acute thromboembolism. For secondary thromboprophylaxis, indefinite anticoagulation with a prophylactic dose of DOACs is suggested, alongside regular follow-up. Dose-adjusted warfarin remains a second-line option (LoE 4).
• (3)AT deficiency: for treatment of an acute thrombotic event, using full-dose DOACs or LMWH bridging to warfarin is suggested. LMWH monotherapy is ineffective in cases of AT deficiency due to varying levels of heparin resistance, and dosage adjustments are necessary if LMWHs are unavoidable. AT concentrates are indicated in cases of refractory thrombosis or DIC or during perioperative or perinatal periods. For secondary thromboprophylaxis, lifelong anticoagulation with dose-adjusted DOACs or dose-adjusted warfarin is suggested, alongside with regular follow-up (LoE 4).
• (4)Heterozygous factor V Leiden or prothrombin G20210A mutation: standard anticoagulation therapy for a duration of 3–6 months is suggested (LoE 3).
• (5)AT-resistance-associated F2 mutations: DOACs or dose-adjusted warfarin is suggested for both anticoagulation therapy and secondary prophylaxis (LoE 4).
• (6)Homozygous or combined hereditary deficiencies: lifelong anticoagulation with therapeutic-dose DOACs or dose-adjusted warfarin is suggested. Adjustments to the anticoagulation strategy should be guided by thrombotic or bleeding symptoms, renal function, and D-dimer trends (LoE 4).

In addition to anticoagulation therapy, the management of acute VTE also encompasses thrombolysis, thrombectomy, and other advanced modalities, which are beyond the scope of this guideline. PC and PS are vitamin K-dependent anticoagulant proteins. When warfarin monotherapy is employed for the treatment of VTE, its mechanism of action precipitates a concurrent decline in PC and PS levels. This reduction exacerbates the hypercoagulable state. Even when initial anticoagulation is achieved through heparins, transitioning to warfarin therapy carries the potential for warfarin-induced skin necrosis, as is well documented in the literature, although this remains a rare phenomenon. Antithrombin deficiency, even in mild forms, can attenuate the ability of heparins to prolong activated partial thromboplastin time. In cases of severe AT deficiency, the administration of heparins alone proves insufficient to achieve a satisfactory anticoagulant effect.⁴ Patients with a single heterozygous mutation in either factor V Leiden or the prothrombin G20210A generally demonstrate a low-to-modest risk of VTE recurrence. In contrast, those harboring multiple or complex genetic abnormalities exhibit significantly higher risk profiles, frequently requiring lifelong anticoagulation.⁵ Prolonged anticoagulation requires vigilant monitoring of clinical signs indicative of either thrombosis or hemorrhage, facilitating timely modification of the therapeutic strategy accordingly.

Hereditary thrombophilia remains a relatively rare condition, and high-quality clinical trials addressing its diagnosis, treatment, and long-term management are notably scarce. The recommendations provided herein are largely informed by case reports, case series, and a few cohort studies as part of expert opinion. As advancements in clinical research yield novel diagnostic tools and therapeutic strategies—such as factor XI inhibitors and gene therapies—future updates to this guideline will be undertaken to integrate emerging evidence.

Funding and acknowledgments

This work was supported by the Chang Jiang Scholars Program (No. 2022161). The funder had no role in the development of this guideline.

Declaration of interests

The authors declare no conflicts of interest.

Published Online: April 01, 2025