Polymorphisms of the human platelet antigens HPA-1, HPA-2, HPA-3, and HPA-5 on the platelet receptors for fibrinogen (GPIIb/IIIa), von Willebrand factor (GPIb/IX), and collagen (GPIa/IIa) are not correlated with an increased risk for stroke.
Carlsson LE, Greinacher A, Spitzer C, Walther R, Kessler C. Stroke. 1997 Jul; 28(7):1392-5.