A variant form of Bernard-Soulier syndrome: mild haemostatic defect associated with partial platelet GPIb deficiency

Platelets from patients with Bernard-Soulier syndrome (BSS) are larger than normal and demonstrate characteristic aggregation abnormalities. A molecular defect involving platelet membrane glycoproteins has been established as the primary abnormality, and the major defect is described as an absence of GPIb, the receptor for von Willebrand factor, which prevents the adhesion of BSS platelets to damaged endothelium. Associated deficiencies of GPV and GPIX are also recognized. The overall clinical effect is a haemorrhagic tendency which, although variable, is severe at times in all patients. We report a child who presented with the typical morphological and aggregation abnormalities associated with BSS, but who had negligible bleeding problems. Further investigation revealed a significant but incomplete deficiency of GPIb and of GPV and GPIX. This case suggests that BSS may be a heterogeneous disorder with clinical consequences dependent on the extent and complexity of the platelet membrane glycoprotein deficiency.