[Factor XII deficiency - Hageman trait. Report of 2 cases]

For the first time in our literature we have described the two cases of hereditary deficiency of factor XII (Hageman trait), a very rare disorder. It was discovered when a long clotting time was found in our patients during the course of a preoperative evaluation. Abnormal thrombelastogram, with a picture typical for hemophilia, gave as a reason to continue with laboratory investigation. The laboratory findings showed us a very low value of factor XII in one case, and total absence of factor XII in the other.