Summary
Thrombomodulin is an endothelial cell membrane glycoprotein that promotes protein
C activation. It has been clearly demonstrated that the anticoagulant functions of
the protein C system are important in the prevention of thromboembolic disease. Patients
with protein C or protein S deficiency and/or resistance to activated protein C (APC
resistance) are at higher risk for developing thromboembolic disease. The first mutation
in the thrombomodulin gene was discovered in an American patient suffering from pulmonary
embolism at the age of 45 (Öhlin and Marlar 1995). Here we report a case of sagittal
sinus thrombosis in a 42-year-old Swedish woman. She was found to carry a heterozygous
point mutation changing G127 to A, predicting an Ala25 to a Thr change in the mature thrombomodulin protein. This mutation was also found
in her 16-year-old daughter, who so far has not suffered from any thrombotic events.
The patient had no other detectable prothrombotic genetic defects associated with
the coagulation system. This case supports the hypothesis of an association between
mutations in the thrombomodulin gene and venous thrombosis.