Schematic representation of the structure of the GPIIb (α IIb) gene (ITGA2B) together with a representative spectrum of the types of genetic abnormalities that give rise to Glanzmann thrombasthenia (GT). The defects responsible for variant forms of the disease are in blue type, those which are prevalent in ethnic groups are in green. Asterisks indicate the number of times that the same genetic defect has been described in apparently unrelated families. For a continually updated list of defects please consult the ISTH database http://sinaicentral.mssm.edu/intranet/research/glanzmann. UTR: untranslated region, del = deletion, ins = insertion, inv = inversion, term = premature termination, stop = stop codon. For simplicity, the initial genetic defect is highlighted. Frameshifts and aberrant splicing are not always noted.