A proportion of unexplained stroke caused by inherited and acquired thrombophilia may be excluded after checking a list of conditions, including anti-thrombin III deficiency, prothrombin gene mutation, Factor V Leiden mutation, protein C and S deficiency, antiphospholipid antibody syndrome, methylenetetrahydrofola reductase mutation, and hyperhomocysteinemia [59]. Here, F5 is linked to hyperhomocysteinemia.