This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding Disorders, Subject name: Pathology
Mega platelets are seen in? 
Select and explain. 
A. Glanzmann thrombasthenia, B. Von willebrand disease, C. Wiskot-Aldrich syndrome (WAS), D. Bernard soulier syndrome
D: Bernard soulier syndrome
Answer: D: Bernard soulier syndrome 
Explanation: Ans. is 'd' i.e., Bernard souiier syndrome Bernard soulier syndromeo It is an autosomal recessive disorder due to deficiency or dysfunction of glycoprotein Ib-IX (Gp Ib/IX). Thus there is defect in platelet adhesion.o Platelet aggregation is normal in response to standard agonists like collagen, ADP or thrombin. But platelets fail to aggregate in response to ristocetin (as ristacetin facilitates binding of vWF and Gp lb- IX).o There may be thrombocytopenia with abnormally large platelets.o There is prolonged BT. vWF is normal.About other optionso Small sized platelets are characteristic of Wiskot-Aldrich syndrome (WAS)o Platelet morphology is normal in Glanzmann thrombasthenia & Von willebrand disease.