Coagulation Disorders USMLE Step 1 Practice Question
A 12 year old boy is evaluated for recurrent epistaxis and excessive bleeding after minor cuts. Laboratory studies show thrombocytopenia and prolonged bleeding time. Platelet aggregation studies are normal with ADP but absent with ristocetin. Peripheral smear shows giant platelets. Which of the following is the most likely defective protein?
Answer choices
- AProtein C
- BGlycoprotein IIb IIIa
- CFactor VIII
- DVon Willebrand factor
- EGlycoprotein IbCorrect answer
- FThromboxane A2 synthase
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