Further studies on the abnormal factor X (factor X Friuli) coagulation disorder. A report of another family.

Another patient with a congenital coagulation disorder due to the presence of an abnormal factor X (factor X Friuli) is presented. The proposita was a 43-yr-old white female who had a bleeding tendency from early childhood (epistaxes, monorrhagias, bleeding after tooth extractions and other surgical procedures, posttraumatic hemarthroses, bleeding from the gums and postpartum hemorrhages). The coagulation work-up demonstrated a prolonged prothrombin time, prolonged partial thromboplastin time, abnormal prothrombin consumption, and abnormal thromboplastin generation corrected by normal serum. Factors II, V, VII, IX, and XII were within normal limits. Platelets, vascular tests and fibrinolysis were normal. Mr. Stuart’s plasma failed to correct the defect of the proposita’s plasma, but a known factor VII deficient plasma was able to correct the abnormality. The factor X assay was low (6-9%) only when tissue thromboplastin, whole or partial, was used. When Factor X was assayed with a Stypven-cephalin mixture, normal or near normal values were observed. Likewise, the Stypven-cephalin clotting time, the Stypven clotting time and the factor II + factor X level using a Stypven-cephalin mixture were normal. The presence of the abnormal factor X was demonstrated immunologically. The defect, like classical factor X deficiency, is transmitted as an autosomal incompletely recessive trait. The mother and the two children of our proposita had factor X levels varying from 38 to 56% of normal and were considered to be heterozygotes.