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).
^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
^Persons with Quebec platelet disorder have a tandem duplication of PLAU, the urokinase plasminogen activator gene. Paterson AD, Rommens JM, Bharaj B, Blavignac J, Wong I, Diamandis M, Waye JS, Rivard GE, Hayward CP. Blood. 2010 Feb 11;115(6):1264-6. Epub 2009 Dec 9