Diversity of glycoprotein deficiencies in Glanzmann's thrombasthenia

The platelet proteins of 9 thrombasthenic patients from 7 families were analysed by high resolution two-dimensional gel electrophoresis (HR-2DE) and crossed immunoelectrophoresis (CIE). In 7 patients both glycoproteins (GPs) IIb and IIIa were absent or reduced to roughly the same extent. In two related patients only a trace of GP IIb-IIIa complex was detected in CIE, but HR-2DE revealed a glycopeptide in the position of GP IIIa in an amount comparable to type II thrombasthenia. This GP IIIa-like component was neither recognized normally by anti-GP IIb-IIIa antibodies nor labeled by surface iodination. In unreduced-reduced two-dimensional gel electrophoresis two components were observed in the region of GP IIIa. The assumption of a structural variant of GP IIIa in the two related patients is discussed.