Abnormal platelets observed in blood films from patients with ARC syndrome. Romanowsky (Wright-Giemsa)–stained blood films from 3 patients with ARC syndrome (A-C) and a neonatal control (D) visualized using oil-immersion 63×/1.32-0.6 objective lenses). Large homogeneous, nongranular gray-appearing platelets (arrows) are observed in the fetal (A), the related neonatal (B), and unrelated neonatal (C) patients with ARC syndrome (A). Inset (C) shows magnified view of a typical large platelet compared with an erythrocyte taken from the top right corner of the underlying image. Normal neonatal control platelets (D) are typically smaller, granular, and stained dark blue (arrows).