CREATE TABLE table_1557752_1 (prothrombin_time VARCHAR2, condition VARCHAR2)

What is the prothrombin time in Von willebrand disease?
SELECT prothrombin_time FROM table_1557752_1 WHERE condition = "Von Willebrand disease"
SELECT "prothrombin_time" FROM "table_1557752_1" WHERE "Von Willebrand disease" = "condition"