Inclusion Criteria- Subject diagnosed by a study neurologist as having had a symptomatic ischemic stroke in the past.
- Head Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) done within 7 days of symptom onset confirms absence of etiology other than ischemic stroke.
- Subject reports having at least one living sibling with a stroke.
- Subject is 18 years of age or older.
Exclusion Criteria- The index ischemic stroke occurred within 48 hours after a cardiovascular or cerebrovascular procedure.
- The index ischemic stroke occurred within 60 days after a non-traumatic subarachnoid hemorrhage.
- The subject has brain biopsy-proven central nervous system vasculitis.
- The subject is known to have any one of the following genetic disorders: CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), Fabry's disease, homocystinuria, MELAS (Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, Stroke), or sickle cell anemia.
- The subject has a mechanical aortic valve or mechanical mitral valve.
- The subject had untreated or actively treated bacterial endocarditis at the time of the index ischemic stroke.