[Variant forms of von Willebrand's disease]

Abnormalities of platelet and plasma Willebrand's factor produce noticeable effects on the clinico-laboratory manifestations of Willebrand's disease. This is confirmed by more pronounced gravity of the hemorrhagic syndrome, the lack of the correcting effect in response to physiological conditions (pregnancy) and administration of DDAVP in contrast to beneficial effect seen in patients with normal content of Willebrand's factor in platelets.