Deep vein thrombosis during enoxaparin prophylactic treatment in a young pregnant woman homozygous for factor V Leiden and heterozygous for the G127 -> A mutation in the thrombomodulin gene

Variability of thrombotic disease among individuals homozygous for factor V Leiden has been described. It has been shown that some thrombotic patients carry an additional genetic risk factor such as protein C, protein S, anti thrombin deficiency or the G20210A mutation on the prothrombin gene. The oc currence of a deep vein thrombosis during enoxaparin prophylactic treatment in a pregnant woman homozygous for factor V Leiden, without other known pr othrombotic genetic factors, led us to investigate her thrombomodulin gene. We found that the patient was heterozygous for the previously described G( 127) --> A mutation, which results in an Ala(25) --> Thr substitution. Furt hermore, for this patient, the allelic combination at the 1418 polymorphic site was C/T, which predicts an Ala (455) --> Val replacement. Although lar ger studies are required, this case report suggests that thrombomodulin gen e mutations could be an additional genetic risk factor for thrombosis in ca rriers of the factor V Leiden mutation. Blood Coagul Fibrinolysis 11:761-76 5 (C) 2000 Lippincott Williams & Wilkins.