Novel Mutations in the GPIIb and GPIIIa Genes in Glanzmann Thrombasthenia

Background: Glanzmann thrombasthenia (GT) is an inherited autosomal recessive platelet disorder characterized by a complete or partial lack, or mutation, of the GPIIb/IIIa complex (integrin αIIbβ3) on the thrombocytes' surface, leading to a severe bleeding syndrome. Material and Methods: Molecular genetic analysis was performed in patients with suspected GT. The aim of the present study was the identification of new natural variants, their impact on platelet function, and their relation to the risk of bleeding. Results: Expression of the platelet integrin αIIbβ3 was determined by flow cytometry. Mutations were identified through sequencing of cDNA and genomic DNA. In addition, platelet function studies (PAC-binding, aggregations) were implemented. The study included 25 patients revealing 13 mutations (GPIIb: n = 9; GPIIIa: n = 4). Two of the 13 mutations were previously described (T207I; L214P). The remaining mutations have not been published yet, whereas 1 mutation in 2 unrelated families was identical (3062 T→C). Conclusion: All patients with less than 25% of present αIIbβ3 have a medical history of bleeding.