Residual amounts of glycoproteins IIb and IIIa may be present in the platelets of most patients with Glanzmann's thrombasthenia

Glanzmann's thrombasthenia is an inherited bleeding disorder characterized by abnormalities of platelet membrane glycoproteins (GP) IIb and IIIa. Most patients, usually designated as type I, have been reported to have undetectable levels of GP IIb and GP IIIa with the assay used. We have used polyclonal rabbit antibodies against GP IIb and GP IIIa in a sensitive immunoblot procedure capable of revealing trace amounts of these glycoproteins. Platelets from nine thrombasthenic patients, including seven with type I disease, were studied. GP IIIa, although decreased, was clearly detectable in platelets of eight patients and GP IIb was identified in five. Our findings suggest that residual quantities of GP IIb and GP IIIa are present in most patients with thrombasthenia and therefore that major deletions in the gene or genes encoding these proteins are uncommon.