This study will measure the frequency of several coagulation factor abnormalities (factor V Leiden, prothrombin 20210A, protein C, protein S, antithrombin III, and antiphospholipid antibodies) in children with a history of porencephaly and stroke, and will compare these to the prevalence of these mutations in population controls and family members. We will also describe the exogenous conditions which in concert with these coagulation factors, may have led to the development of thrombosis in these children....