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What is Glanzmann thrombasthenia is due to defect in and explain in detail?
Platelet Function Defects:- * Defect in platelet adhesion:- Bernard Soulier syndrome,Von Willebrand's disease * Defect in platelet aggregation:- Glanzmann thrombasthenia, Afbrinogenemia * Defect in platelet secretion:- Storage pool disorders,drugs (NSAID) induced Glanzmann thrombasthenia is due to defective platelet aggregation, due to defect in receptor Gp IIb-IIIa Bernard Soulier syndrome is due to defective platelet adhesion due to defect in Gp Ib-IX * In the image shown above, agglutination is seen with theristocetin. There is no aggregation with ADP, adrenaline or collagen. * Possible diagnosis:- Glanzmann's thrombasthenia or afibrinogenaemia * In the image above, there is lack of agglutination with ristocetin, but agglutination occurs with other agonists. * Possible diagnosis:- Von Willebrand Disease (vWD) or Bernard Soulier Syndrome (BSS). * vWD is differentiated from BSS by repeating the platelet aggregometry after adding cryoprecipitate. * After adding cryoprecipitate (which contains von Willebrand factor), agglutination occurs with ristocetin.Then a diagnosis of vWD can be made. * BSS - Disorder of platelet adhesion, due to defect in Ib-IX receptor * Glanzmann thrombasthenia - Disorder of platelet aggregatation, due to defect in IIb-IIIa receptor. * Glanzmann's thrombasthenia (GT) is an autosomal recessive inherited platelet function defect characterized by normal platelet count, prolonged bleeding time and abnormal clot retraction. * Clot retraction test is a measurement of platelet function. Clot retraction test is abnormal in thrombocytopenia, thrombasthenia and polycythemia Ref:- Robbins Basic Pathology 9th Edition; Pg num:- 660