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 [Hayward CP, Rivard GE, Kane WH, Drouin J, Zheng S, Moore JC, Kelton JG. An autosomal dominant, qualitative platelet disorder associated with multimerin deficiency, abnormalities in platelet factor V, thrombospondin, von Willebrand factor, and fibrinogen and an epinephrine aggregation defect. "Blood" (1996) 87: 4967-78.] [Diamandis M, Veljkovic DK, Maurer-Spurej E, Rivard GE, Hayward CPM. Quebec platelet disorder: features, pathogenesis and treatment. "Blood Coagulation and Fibrinolysis" (2008). 19(2): 109-119] . The disorder is characterized by large amounts of the fibrinolytic enzyme urokinase-type plasminogen activator (u-PA) in platelets [Kahr, 2001] . 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 [Sheth, 2003] . These proteins include platelet factor V, Von Willebrand factor, fibrinogen, thrombospondin-1, and osteonectin [Kahr, 2001] . 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) [Diamandis & Adam, 2006] . Individuals with QPD are at risk for experiencing a number of bleeding symptoms, including joint bleeds, hematuria, and large brusing [McKay & Haq, 2004] . The genetic cause of QPD has not yet been determined.

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