Synonym: Factor V Quebec, BDPLT5
Chromosome location: 10q22.2
Gene affected: PLAU (plasminogen activator, urokinase), a serine protease
Mechanism: gain-of-function defect in fibrinolysis, with a degradation of alpha-granule proteins and accelerated clot lysis
Inheritance: autosomal dominant
Clinical features:
(1) familial bleeding disorder
(2) delayed bleeding (12 to 4 days after a hemostatic challenge), often prolonged
(3) joint bleeds with or without arthropathy
(4) other signs of bleeding disorder: bruising, nosebleeds, hematuria, abnormal bleeding after dental extraction, excessive bleeding after trauma, menorrhagia
(5) problems with wound healing
(6) variable need for transfusion because of bleeding
(7) positive response to a fibrinolytic inhibitor (tranexamic acid or aminocaproic acid)
Laboratory findings:
(1) variable thrombocytopenia
(2) variable iron deficiency from recurrent bleeding
(3) tests performed on plasma are usually normal
Complications:
(1) venous thrombotic event during therapy with fibrinolytic inhibitor
