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    Poster Networking

    Hemophilia and Rare Bleeding Disorders

    Poster Networking Session

    PB0237 - Inhibitor in congenital FXI deficiency

    Sunday, June 25, 2023
    18:30 – 19:30 ET
    Room: Exhibition

      Co-Author(s)

    • TF

      Tereza Fenclová (she/her/hers)

      laboratory scientist
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion
      Prague, Hlavni mesto Praha, Czech Republic

      • Co-Author(s)

    • DP

      Dana Provaznikova, PhD (she/her/hers)

      laboratory researcher
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
      Prague, Hlavni mesto Praha, Czech Republic

    • RL

      Renata Liskova

      laboratory technician
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
      Prague, Hlavni mesto Praha, Czech Republic

    • AR

      Alena Radovska

      laboratory technician
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
      Prague, Hlavni mesto Praha, Czech Republic

    • MS

      Martina Simonikova

      laboratory technician
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
      Prague, Hlavni mesto Praha, Czech Republic

    • JL

      Jan Loužil

      physician
      Centre for Thrombosis and Hemostasis, Institute of Hematology and Blood Transfusion
      Prague, Hlavni mesto Praha, Czech Republic

    • DÄ

      Daniela Češpivová

      laboratory technician
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion
      Prague, Hlavni mesto Praha, Czech Republic

    • FM

      Frantisek Marecek

      laboratory scientist
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
      Prague, Hlavni mesto Praha, Czech Republic

    • PS

      Peter Salaj

      physician
      Centre for Thrombosis and Hemostasis, Institute of Hematology and Blood Transfusion
      Prague, Hlavni mesto Praha, Czech Republic

      • Presenting Author(s)

    • IH

      Ingrid Hrachovinova

      head of laboratory
      National Reference Laboratory for Disorders in Hemostasis, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
      Prague, Hlavni mesto Praha, Czech Republic

    Background: Factor XI (FXI) deficiency is a rare bleeding disorder that causes an increased bleeding tendency after trauma or surgery.

    Aims: In our case report, we study genetical and functional grounds of a patient with very low level of FXI and no bleeding symptoms.

    Methods: The level of FXI was investigated by the coagulation one-stage assay (FXI:C), the determination of the inhibitor by the Bethesda method, lupus anticoagulant (LA) according to the recommendations of the SSC ISTH. Furthermore, analysis of genomic DNA by next generation sequencing was performed and verified by Sanger sequencing.

    Results: The patient was first examined when a prolonged APTT (ratio 1.88) was detected, and clearly positive LA was confirmed. Levels of factors VIII, IX, XI and XII were all reduced on repeat examination but normalized with sample dilution except for FXI, which was repeatedly very low (~12 IU/dl). The patient had no history of bleeding, even after surgery. After examining the family members, we found that the patient's father has a congenital FXI deficiency (~5 IU/dl), confirmed by two heterozygous mutations and has history of epistaxis and bleeding complications. With the information, we examined the patient for a presence of family mutations in the FXI gene. Only one familial mutation was found (p.Thr150Met) that is associated in heterozygous form with FXI:C 23-52 IU/dl. Due to unexpectedly low FXI, patient was tested for FXI inhibitor and we found 7.8 B.U/ml.

    Conclusion(s): We demonstrate the unique case of FXI inherited deficiency with the presence of inhibitor and no bleeding symptoms. It is possible that the simultaneous procoagulant action of LA corrects this deficiency clinically. This case should be followed carefully and factor substitution for surgery should be considered, since the hemostatic balance is complicated and could lean towards bleeding easily.