Glanzmann thrombasthenia 1

A platelet type bleeding disorder characterized by lifelong mucocutaneous bleeding, markedly impaired platelet aggregation, and absent or severely reduced clot retraction due to failure of the αIIbβ3 integrin complex to bind fibrinogen. Platelets appear normal in number and morphology, but aggregation responses to physiologic agonists (including ADP, collagen, epinephrine, and thrombin) are severely decreased or absent, while ristocetin‑induced agglutination remains normal. Biallelic loss‑of‑function ITGA2B variants reduce or abolish surface expression of the αIIbβ3 receptor, preventing fibrinogen‑mediated platelet bridging and producing the classic Glanzmann thrombasthenia phenotype.