Fatal hemorrhage from mucosal surfaces has also been observed in Glanzmann's thrombasthenia, a rare autosomal recessive disorder. Platelet morphology and platelet count are normal, but the bleeding time is long. Ristocetin-induced agglutination, however, is normal. The binding of fibronectin and vWF to thrombasthenic platelets is also defective, presumably because these factors also have a binding site somewhere on the GPIIb-IIIa complex. Acute hemorrhage is treated as in Bernard-Soulier syndrome.
Moderate thrombocytopenia is present, and the bleeding time is prolonged.
The platelets are larger than normal and appear agranular because of the absence of alpha granules. Platelet aggregation with collagen is abnormal. Bleeding episodes should be treated by infusion of normal platelets. Another rare disorder, the dense granule deficiency syndrome, is characterized by mucosal bleeding associated with a normal platelet count, normal platelet morphology, and variable prolongation of the bleeding time. Platelet aggregation with ADP and collagen are abnormal.