F2 and Stroke: Note that all other possible confounding factors for stroke were excluded by doing additional tests, which are all normal, including hemoglobin electrophoresis, paroxysmal nocturnal hemoglobinuria marker, proteins S and C, antithrombin III, factor Leiden V, erythrocyte sedimentation rate, antinuclear antibody, rapid plasma reagin, anticardiolipin antibody, vitamin B12 levels, homocysteine levels, prothrombin and partial prothrombin times, hemoccult stool, TEE, and lupus anticoagulant antibodies.