SERPINC1 and hyperinsulinemic hypoglycemia, familial, 4: Besides severe inflammation in patients with retinal vasculitis, other factors causing CRVO in patients with CD have been proposed, including abnormalities in the coagulation system (protein C and S deficiency, high plasminogen activator inhibitor levels, antithrombin III deficiency, and hyperfibrinogenemia) and change in the vessel walls [8–11].