title: [A patient with isolated prolongation of aPTT without hemorrhagic diathesis anamnesis: severe, hereditary factor XII deficiency].
abstract: By virtue of a severely prolonged aPTT with a normal thromboplastin time (prothrombin time) and a normal thrombin time, severe FXII deficiency has been diagnosed in a woman without a bleeding diathesis or a history of thromboembolic complications. A deficiency of a factor of the contact activation system (FXII, prekallikrein, high molecular weight kininogen) is usually diagnosed during routine coagulation tests demonstrating a prolonged aPTT. The severe and partial deficiency of FXII, of prekallikrein or high molecular weight kininogen is not associated with a bleeding tendency. In contrast, severely factor XI deficient subjects may suffer from a mild hemorrhagic diathesis, whereas FVIII deficiency (hemophilia A, autoimmune "hemophilia", von Willebrand disease) and FIX deficiency (hemophilia B) are associated with a bleeding tendency of varying severity, depending on the clotting activity of FVIII or FIX, respectively. An isolated prolongation of the aPTT due to a lupus anticoagulant, however, is frequently associated with arterial and/or venous thrombosis. Therefore, in case of a prolongation of the aPTT, its cause has to be determined.
authors.affiliation: Hämatologisches Zentrallabor der Universität Bern, Inselspital, Bern.
authors.forename: S
authors.initials: S
authors.lastname: Zeerleder
authors.forename: L
authors.initials: L
authors.lastname: Asmis
authors.forename: M
authors.initials: M
authors.lastname: Redondo
authors.forename: I
authors.initials: I
authors.lastname: Sulzer
authors.forename: B
authors.initials: B
authors.lastname: Lämmle
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005175:Factor XII Deficiency / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D006474:Hemorrhagic Disorders / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D010314:Partial Thromboplastin Time; D011517:Prothrombin Time