This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bleeding disorder, Subject name: Pathology
[{'content': 'In von Willebrands disease there is: \nSelect and explain. \nA. Isolated prolonged PTT with normal PT, B. Normal PTT with normal PT, C. Prolongation of both PT and PTT, D. Prolongation of thrombin time', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Von Willebrand disease (VWD) - - Autosomal dominant disorder - The main source of plasma von-Willebrand factor is endothelial cells. - vWF circulates in the plasma in association with factor VIII. - Patients with VWD have defects in platelet function despite a normal platelet count - Deficiency of von willebrand factor (VWF -promote platelet adherence and activation) causes | platelet adhesion ( |BT) and | Intrinsic pathway activity ( | aPTT) . - von willebrand factor can also be found in : Platelet granules Subendothelium Endothelial cells within cytoplasmic vesicles called Weibel-Palade bodies C/F Spontaneous mucosal bleeding - Petechiae /purpura /epistaxis / melena excessive bleeding from wounds menorrhagia Lab findings - Platelet count - Normal Prothrombin time - Normal Bleeding time - Increased Activated paial thromboplastin time (aPTT)-Increased Rx - Desmopressin for mild form - Cryoprecipitate for severe form', 'role': 'assistant'}]