Platelet fibrinogen binding studies demonstrate that platelets from patients with Glanzmann thrombasthenia cannot bind fibrinogen in response to ADP stimulation. The upper curve is of platelets from a healthy subject and the 3 lower ones are from 3 different patients. Reprinted with permission from Bennett JS, Vilaire G. J Clin Invest. 1979;64:1393-1401.³¹