The condition is diagnosed by blood tests in the laboratory when it is noted that special blood clotting test are abnormal. Specifically prothrombin time (PT) or activated partial thromboplastin time (aPTT) are prolonged. The diagnosis is confirmed by an assay detecting very low or absent FXII levels. The FXII (F12) gene is found on chromosome 5q33-qter. In hereditary angioedema type III an increased activity of factor<unk>  has been described.
Factor XII deficiency
Factor VII deficiency
Factor XIII deficiency
Factor I deficiency
COAT platelet defect
Factor X deficiency
Protein C deficiency
Vitamin K deficiency