Reduction, abnormal size, and distribution of platelet-dense granules. (A-D) Mepacrine staining of platelets from a healthy control (A-B) and the patient (C-D). Representative staining patterns are shown. (E) Fluorescence histograms of mepacrine-stained platelets from the patient (blue) and a healthy control (red). Unstained platelets from the patient are shown in gray. (F-H) Whole-mount electron microscopy of representative platelets from a control (F) and the patient (G-H). Granules were present in 41% of the patient's platelets.