In this task, you will be given a sentence. You need to reconize the name of the disorder or disease. Disease is a disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury. Although there might be several correct answers, you need to write one of them.
Q:  Neither vWf nor vWf propolypeptide ( von Willebrand antigen II ) were detectable in plasma , platelets , or endothelial cells of the homozygous mutant mice .
A: 
von Willebrand