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F13B gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

F13B gene

The F13B gene provides instructions for the B subunit of factor XIII, a protein essential for stabilizing blood clots and supporting wound healing.

Normal Function

The F13B gene provides instructions for making the B subunit of a protein called factor XIII. This protein is a coagulation factor essential for normal blood clotting. Factor XIII acts at the end of the coagulation cascade to strengthen and stabilize newly formed clots, preventing further blood loss.

In the bloodstream, factor XIII consists of two A subunits (produced by the F13A1 gene) and two B subunits. The B subunits function to carry and stabilize the A subunits, protecting them from degradation. When a clot forms, the subunits separate, and the A subunits are activated to link together molecules of fibrin, the material that forms the clot. Factor XIII is also believed to play roles in wound healing, immune function, pregnancy maintenance, bone formation, and the growth of new blood vessels (angiogenesis).

Health Conditions Related to Genetic Changes

Factor XIII deficiency

At least 17 mutations in the F13B gene have been found to cause inherited factor XIII deficiency, a rare bleeding disorder. Mutations in this gene severely reduce the amount or disrupt the function of the B subunit, which prevents it from stabilizing and protecting the A subunit. The resulting loss of factor XIII activity weakens blood clots, leading to an increased risk of abnormal bleeding episodes, including life-threatening intracranial hemorrhage.

Other Names for This Gene

  • coagulation factor XIII B chain precursor
  • coagulation factor XIII, B polypeptide
  • fibrin-stabilizing factor B subunit
  • FXIIIB
  • protein-glutamine gamma-glutamyltransferase B chain
  • TGase
  • transglutaminase B chain

Frequently Asked Questions

Patients may present with delayed wound healing, easy bruising, spontaneous mucosal bleeding, or recurrent hemarthroses. A hallmark is a prolonged bleeding time that does not improve with standard factor replacement, suggesting a specific deficiency in factor XIII. A detailed bleeding history and a factor XIII activity assay are key to suspicion.
Diagnosis starts with a clotting screen showing normal PT, aPTT, and fibrinogen but a low factor XIII activity level (<50 %). A functional assay (e.g., amidolytic or clot solubility test) confirms deficiency. Genetic testing of F13B identifies pathogenic variants, which helps confirm the diagnosis, informs prognosis, and guides family counseling.
Treatment involves intravenous infusion of plasma‑derived or recombinant factor XIII concentrate. The dosing schedule depends on the severity and bleeding risk but typically ranges from 50–100 IU/kg every 2–4 weeks to maintain activity above 10–15 %. In acute bleeding, higher doses are given until hemostasis is achieved. Regular monitoring of factor XIII levels ensures adequate protection.
Yes, factor XIII deficiency increases the risk of postpartum hemorrhage and placental abruption. Pre‑delivery planning includes ensuring adequate factor XIII levels, arranging for blood products, and having a multidisciplinary team (obstetrician, hematologist, anesthesiologist) ready. Post‑delivery, patients often receive prophylactic factor XIII infusions to prevent bleeding.===
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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