Impaired platelet aggregation and degranulation. (A) Platelet aggregation after stimulation with ADP from the patient (bottom line) and 2 healthy controls (top lines). (B) Degranulation of activated platelets assessed by CD63 expression. The data show the mean fluorescence intensity (MFI) of anti-CD63-stained unstimulated or thrombin-stimulated platelets from the patient and 3 controls, including both parents. (C) Baseline expression of CD62 and up-regulation upon activation with the indicated concentrations of thrombin.