Thrombasthenia: A Heterogenous Disorder

Abstract

We investigated the relation of the expression of platelet specific allo-antigens of Zw-, Ko- and Bak system and the glycoprotein (GP) and protein composition of platelets and isolated platelet membranes from a group (7) of Glanzmann Thrombasthenia (GT) patients. Using the platelet immunofluorescence test and the platelet agglutination test platelets of 6 GT patients were typed Zw Zwb negative, Koa and Kob positive and Bak (a) negative. These findings suggested a linkage between a regulator gene concerned in the synthesis of GP IIb and IIIa and the gene responsible for Bak (a) negativity. Quantitative polyacrylamide gelelectrophoresis revealed that platelets from one GT patient had the strongest periodic acid Schiff’s reagent (PAS) staining of GP IIIa (although just outside the normal range) and in addition showed a weak positive reaction with anti-Zwa serum, indicative of Zw3 antigenic marker to be associated with GP IIIa. The remaining 6 patients had a marked reduction in PAS staining of GP IIb and IIIa (mean value 80%) and protein staining of these GPs. GP profiles of thrombasthenic platelets also showed alterations in the GP I (one GT patient had two major PAS staining bands in this region) and GP IIIb region (broad diffuse PAS staining band). Total GP, GP IIIa and IIIb content, number and content of GP I and protein composition varied per patient and strongly suggested that thrombasthenia is a heterogenous disorder.