A novel type 2A von Willebrand factor mutation (V1499E) associated with variable clinical expression.

We have identified a previously unreported mutation, V1499E, with a high penetrance in a family with type 2A von Willebrand disease. Affected family members were difficult to identify owing to variable von Willebrand factor (VWF) levels, variable expression of VWF multimers, and clinical symptoms. Recombinant V1499E-VWF was more readily cleaved by ADAMTS13 than the wild-type protein, suggesting that V1499E is the causative mutation.

Correlation between the potency of a beta2-glycoprotein I-dependent lupus anticoagulant and the level of resistance to activated protein C.

The antiphospholipid syndrome is characterized by the occurrence of vascular thrombosis combined with the presence of antiphospholipid antibodies in plasma of patients. It has been published that antibeta2-glycoprotein I (beta2-GPI) antibodies, with lupus anticoagulant activity (LAC), highly correlate with thrombosis. Resistance related to antiphospholipid antibodies against activated protein C (APC) is one of the proposed mechanisms responsible for thrombosis.