Effect of FLNA mutations on platelet morphology. Typical illustrations of platelet morphology as seen for each patient by EM. Discoid control platelets are homogeneous in size, and the α-granules are distributed homogeneously. Several examples are shown for each patient (P1-P3). Note the presence of size heterogeneity with enlarged more rounded platelets intermingled with discoid platelets of normal size. Heterogeneity also is noted in the α-granule content (i,iii,v-vii) with some platelets having few granules (v,vii), whereas giant granules are occasionally seen (ii,iv). Zones enriched in membrane complexes are seen in some giant platelets (i,iv). Bars indicate 1 μm for all EMs.