This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Hemophilia A due to deficiency of \nSelect and explain. \nA. Factor VIII, B. Factor IX, C. Factor X, D. Factr XI', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hemophila A:- \n\nHemophilia A is due to deficiency of factor VIII\nHemophilia A is inherited as an X-linked recessive trait.\nFactor VIII is an intrinsic pathway component required for activation of factor X. \nClinical manifestations are due to defect in coagulation system : -\n\n\nLarge post traumatic ecchymoses or hematoma. Prolonged bleeding after a laceration or any form of surgical procedure.\nBleeding into weight bearing joints.\n\n\nPetechiae are characteristically absent (in contrast to platelet dysfunction where bleeding occur from small vessels of skin and mucous membrane, e,g.: petechiae). \nLaboratory findings :-\n\n□ ↑ PTT □ Normal BT □ Normal PT\nNormal platelet counts Remember \nHemophilia B (christmas disease)\xa0is due to deficiency of factor IX.\nHemophilia B has clinical features and laboratory findings similar to hemophilia A', 'role': 'assistant'}]