Phenotypic heterogeneity among the affected family members. (A) Nanobody binding. Binding of the AU/VWFa-11 nanobody to plasma VWF was higher in most of the affected family members than in pooled normal plasma (PNP), and binding varied considerably among the affected individuals. (B) VWF multimers. Multimer patterns of plasma VWF varied significantly among the affected individuals; whereas some samples lack both high- and intermediate-sized molecular-weight forms, others showed normal multimer patterns. Individual III.4 was an infant and a bleeding survey was not completed for this subject. For each of the VWD patients, 1 μL of plasma was loaded; for the PNP control, 0.5 μL of plasma was loaded.