A stroke is an acute neurologic event leading to death of neural tissue of the brain and resulting in loss of motor, sensory and/or cognitive function. It is said to be the third leading cause of death in the United States. Gunel and Lifton (1996) noted that about 20% of strokes are hemorrhagic, resulting in bleeding into the brain. Ischemic strokes, resulting from vascular occlusion, account for the majority of strokes. Bersano et al. (2008) reviewed genetic polymorphisms that have been implicated in the development of stroke. Candidate genes include those involved in hemostasis (see, e.g., F5; 612309), the renin-angiotensin-aldosterone system (see, e.g., ACE; 106180), homocysteine (see, e.g., MTHFR; 607093), and lipoprotein metabolism (see, e.g., APOE; 107741). See also hemorrhagic stroke, or intracerebral hemorrhage (ICH; 614519).

Increased numbers of platelets in the peripheral blood.

The presence of abnormally high numbers of micromegakaryocytes in the bone marrow. Micromegakaryocytes are mononuclear diploid cells, with a nucleus similar in size to that of a myeloblast or promyelocyte with the cell being less than 30 micrometers in diameter.