A novel homozygous variant of the thrombomodulin gene causes a hereditary bleeding disorder

Makoto Osada, Keiko Maruyama, Koichi Kokame, Ryunosuke Denda, Kohei Yamazaki, Hisako Kunieda, Maki Hirao, Seiji Madoiwa, Nobuo Okumura, Mitsuru Murata, Yasuo Ikeda, Kentaro Watanabe, Yuiko Tsukada, Takahide Kikuchi

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


We report a 19-year-old Vietnamese woman who experienced several life-threatening bleeding events, including ovarian hemorrhage. Blood analysis revealed a decreased fibrinogen level with markedly elevated fibrinogen/fibrin degradation products and D-dimer levels. Despite hemostatic surgery and administration of several medications, such as nafamostat mesylate, tranexamic acid, and unfractionated heparin, the coagulation abnormalities were not corrected, and the patient experienced repeated hemorrhagic events. We found that administration of recombinant human thrombomodulin (rhTM) remarkably improved the patient’s pathophysiology. Screening and sequencing of the TM gene (THBD) revealed a previously unreported homozygous variation: c.793T.A (p.Cys265Ser). Notably, the Cys265 residue forms 1 of 3 disulfide bonds in the epidermal growth factor (EGF)–like domain 1 of TM. Transient expression experiments using COS-1 cells demonstrated markedly reduced expression of TM-Cys265Ser on the plasma membrane relative to wild-type TM. The TM-Cys265Ser mutant was intracellularly degraded, probably because of EGF-like domain 1 misfolding. The reduced expression of TM on the endothelial cell membrane may be responsible for the disseminated intravascular-coagulation–like symptoms observed in the patient. In summary, we identified a novel TM variant, c.793T.A (p.Cys265Ser). Patients homozygous for this variant may present with severe bleeding events; rhTM should be considered a possible treatment option for these patients.

Original languageEnglish
Pages (from-to)3830-3838
Number of pages9
JournalBlood Advances
Issue number19
Publication statusPublished - 2021 Oct 12

ASJC Scopus subject areas

  • Hematology


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