user: ### NOW ANSWER:
Question: What is the prothrombin time of Von Willebrand disease? 
Columns: ['Condition', 'Prothrombin time', 'Partial thromboplastin time', 'Bleeding time', 'Platelet count']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Vitamin K deficiency or warfarin', 'Prolonged', 'Normal or mildly prolonged', 'Unaffected', 'Unaffected']
SQL:

assistant: SELECT COUNT("Prothrombin time") FROM "Table" WHERE "Condition" = 'Von Willebrand disease';