Background: Glanzmann's thrombasthenia (GT), is a rare autosomalrecessive bleeding disorder. Platelets from patients with GT showquantitative or qualitative defects of the platelet membraneglycoprotein (GP) IIb/IIIa complex. A variety of genetic defects inITGA2B and ITGB3 (genes for GPIIb and GPIIIa) has been describedcausing the clinical entity of GT.Patients: A newborn with bleeding symptoms (petechiae) plateletanalyses revealed an inherited primary hemostasis disorder.Methods/Results: Analyses of patient's platelets using flow cytometryand immunoblotting showed absence of GPIIb protein and reduced amountof GPIIIa. Using restriction fragment length polymorphismheterozygosity for the deletion could be identified in the parents andin two siblings. Expression studies in mammalian cells revealed thatthe mutant GPIIb is missing and additionally affects the expression ofwildtype GPIIIa. This deletion leads to a truncation at the veryN-terminal region of the GPIIb protein.Conclusion: The present study describes a patient with GT associatedwith a novel homozygous deletion (c.175delG) in exon 1 of ITGA2B. Thisdeletion led to a reading frameshift and caused a severely truncatedform of GPIIb.