Clinical implications of factor XII deficiency

A patient with known factor XII deficiency underwent extraction of four impacted third molars. Significant preoperative laboratory values included a partial thromboplastin time (PTT) of greater than 100 seconds and a factor XII level of less than 1%. The third molars were removed without any significant intraoperative or postoperative bleeding. Factor XII not only has an important function in the initiation of the intrinsic pathway of the coagulation cascade, but it also plays a significant role in complement activation, kinin generation, and fibrinolysis. It would seem that a deficiency in this factor would have widespread clinical implications. In fact, the only clinical significance seems to be a predisposition to thromboembolism in factor XII deficient patients.