Figure 4. TPM4 insufficiency results in altered platelet morphology.

(A and B) Ultrastructure of platelets from cases 1-II-5 and 1-III-7 carrying the variant, showing the presence of large platelets with numerous vacuoles indicating increased fragility, contrasting the normal discoid platelet appearance in controls. (A) Overview. (B) Detail. Scale bars: 1 μm. (C) Representative electron microscopic pictures illustrating increased size and fragile appearance in Tpm4^Plt53/Plt53 and Tpm4^Plt53/+ compared with Tpm4^+/+ platelets (n = 2; each sample was pooled from 2 individuals). Scale bars: 1 μm. (D) Western blot showing the presence of degraded filamin A and actinin 1 in Tpm4^Plt53/Plt53 and Tpm4^Plt53/+ compared with Tpm4^+/+ platelets. Results are representative of 2 independent experiments. Bottom panel: β-Actin loading control.