Combination of von Willebrand disease type 1 and partial factor XII deficiency in children: clinical evidence for a diminished bleeding tendency

Factor XII deficiency can be associated with a thrombotic and VWF deficienc y with a haemorrhagic clinical course. To study the potential influence of factor XII deficiency on bleeding tendency in patients suffering from VWD w e retrospectively compared the clinical outcome of children with either an isolated factor XII deficiency, an isolated VWD, or a combination of both. Patients with the combined coagulation defect showed significantly fewer bl eeding events when compared to patients with isolated VWD, although ristoce tin cofactor activities were reduced to a comparable degree. As far as aPTT values are concerned, there were no significant differences among the thre e groups. Whether this combination of thrombophilic and haemorrhagic coagul ation disorders is only coincidental or the result of an active modulation of one of the two counteracting coagulation factors is not known at present .