F5 and MELAS syndrome: Some rare risk factors for stroke include hypercoagulable blood disorders (antiphospholipid syndrome, factor V Leiden, protein C/S deficiency), as well as genetic disorders such as cerebral autosomal dominant arteriopathy with subcortical infarcts (CADSIL), moyamoya disease, Ehlers-Danlos syndrome type IV, Fabry disease, and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome.