Fibrinogen Saint-Germain II: Hypofibrinogenemia due to heterozygous γ N345S mutation

We have identified a novel heterozygous fibrinogen γchain mutation, γN345S (Fibrinogen Saint-Germain II), in a subject with hypofibrinogenemia. There was no evidence by mass spectrometry of plasma fibrinogen containing the mutant chain. The hypofibrinogenemia was discovered in a 26-year-old man who experienced extensive deep venous thrombosis of the left leg associated with pulmonary embolism. Investigation of potential thromboembolic risk factors revealed heterozygosity of the factor V R506Q mutation (factor V Leiden) and heterozygosity of the prothrombin gene G20210A mutation.The hypofibrinogenemia may be contributory to the thrombophilic manifestations.