NEW VARIANT FORMS OF von WILLEBRAND'S DISEASE

Abstract

Two unusual variants of von Willebrand's Disease (vWD) have been observed; one resembling Type Ic vWD and one an unclassified variant form of the disease. Both are associated with a history of mild bleeding and with a prolonged bleeding time.Two related patients (father and daughter) presented with reduced vWF activity (RiCoF) and vWF:Ag. Multimer analysis showed the presence of all molecular weight multimers but with a lack of triplet structure. This was confirmed in 3% agarose gels and resembled the pattern of multimers previously described as Type Ic vWD. Both patients responded well to DDAVP.In the second case the patient had a lowered vWF activity (RiCoF) but normal vWF:Ag, analogous to a Type Ila vWD pattern. Mutimer analysis however demonstrated the presence of all MW multimers with a normal triplet structure. This defect was not detected with two monoclonal antibodies that recognise the GPIb binding site on vWF and is thought to represent a minor abnormality in the vWF molecule in this patient.