Glanzmann thrombasthenia 2

A platelet type bleeding disorder characterized by lifelong mucocutaneous bleeding, severely impaired platelet aggregation, and absent or markedly reduced clot retraction due to loss of αIIbβ3‑mediated fibrinogen binding. Platelet number and morphology are typically normal, but responses to physiologic agonists, such as ADP, collagen, epinephrine, and thrombin are severely diminished or absent, while ristocetin‑induced agglutination is preserved. Biallelic loss‑of‑function ITGB3 variants result in reduced or absent β3 integrin production, preventing assembly or surface expression of the αIIbβ3 receptor complex and producing the characteristic Glanzmann thrombasthenia phenotype.