Quebec Platelet Disorder

Quebec Platelet Disorder (QPD) is a rare, autosomal dominant bleeding disorder described in a family from the province of Quebec in Canada. The disorder is characterized by large amounts of the fibrinolytic enzyme urokinase-type plasminogen activator (u-PA) in platelets. Consequently, stored platelet plasminogen is converted to plasmin, which is thought to play a role in degrading a number of proteins stored in platelet α-granules.

These proteins include platelet factor V, Von Willebrand factor, fibrinogen, thrombospondin-1, and osteonectin. There is also a quantitative deficiency in the platelet protein multimerin 1 (MMRN1). Furthermore, upon QPD platelet activation, u-PA can be released into forming clots and accelerate clot lysis, resulting in delayed-onset bleeding (12-24hrs after injury). Individuals with QPD are at risk for experiencing a number of bleeding symptoms, including joint bleeds, hematuria, and large brusing . The genetic cause of QPD has not yet been determined.