“…Factor V Leiden causes the activated form of factor V to be relatively resistant to degradation by activated protein C with www.wjgnet.com Hugh James Freeman, MD, FRCPC, FACP, Series Editor increased generation of thrombin. Factor V Leiden is often detected with venous thrombosis, but, to date, no difference between patients with inflammatory bowel disease and those without inflammatory bowel disease has been defined [18] . In addition, a genetic variation of the prothrombin gene, G20210A, may be associated with deep venous thrombosis, but no definite association between this gene mutation and inflammatory bowel disease has been detected [18] .…”