Plasma [FVIIa] is decreased in patients with SCD. Citrated plasma samples from normal controls or patients with SCD were assayed for plasma [FVIIa] as described in Patients and Methods. Each symbol represents a single data point; samples are included from both Black (•) and Caucasian (○) control subjects. Patient samples include those drawn during steady-state disease (▵) as well as during pain crisis (▴).