The thrombophilic gene polymorphisms, including factor V Leiden, prothrombin G20210A, antithrombin, fibrinogen, type 1 plasminogen activator inhibitor (PAI-1) 4G/5G, and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, are reported to be the genetic determinants of thrombophilia [10,11,12]. The gene discussed is F5; the disease is Rare hereditary thrombophilia.