[Type 2N von Willebrand disease (Normandy)].

Willebrand disease is the most common constitutional abnormality of hemostasis. It reflects a qualitative or quantitative abnormality of von Willebrand factor (vWF) responsible for hemorrhagic syndrome, mainly mucosal, of variable expression. Type 2N (Normandy) is a rare form of von Willebrand disease due to a qualitative abnormality of vWF that disrupts its ability to bind to factor VIII. The disease biologically combines APTT prolongation, a lower level of factor VIII, and a normal or subnormal rate of vWF, which may suggest a mild form of hemophilia A. This confusion can lead not only to a misdiagnosis but also to inappropriate treatment.