The purpose of this study is to find the genes that increase the risk of developing an ischemic stroke using DNA samples collected from concordant (stroke-affected) sibling pairs.

Stroke is the third leading cause of death in the United States and a leading cause of acquired disability in adults. Each year, about 700,000 people experience stroke in the country. Ischemic stroke, which constitutes about 80 percent of all strokes, is a complex genetic disorder--the result of interactions between multiple genes and multiple environmental exposures. Genes affecting cholesterol, blood pressure, clotting, and other factors may increase the risk of ischemic stroke.

In this clinical study, investigators are studying groups of siblings in which at least two of the siblings have had an ischemic stroke. The goal of this multi-center study is to find the genes that increase the risk of developing an ischemic stroke.

To accomplish the aims of the study, researchers are using DNA samples collected from concordant (stroke-affected) sibling pairs to determine if there are regions in the human genome associated with ischemic stroke or that may harbor stroke susceptibility genes.

Two teaspoons of blood will be collected from each participant and submitted for genetic analysis. Understanding the genetic predisposition to stroke could have major benefits for public health.

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.

in-patient or out-patient clinics, local community