The propositus is a 4-year-old boy who presented with a history of excessive bleeding after surgical procedures as well as haematomas and epistaxis.
The defect in haemostasis consisted in an anomaly of the prothrombin consumption tests as the only abnormality while all the other conventional coagulation and fibrinolysis tests as well as platelet function tests were normal. The father of the propositus had no previous history of excessive bleeding but was found to have an abnormal prothrombin consumption index. The reaction to prothrombin conversion, normal at onset, slowed down to less than normal and did not reach completion until 24 h.
The in vivo studies suggest that the effect does not act on the interaction between platelet phospholipid and plasma. The factor II dosage and the electrophoretic mobility of prothrombin of the plasma were normal; nevertheless when studying the purified prothrombin by means of crossed immunoelectrofocusing there appeared an anomaly of pI.
This result suggests the possible existence of an abnormal prothrombin molecule responsible for a slow prothrombin conversion.
CITATION Br J Haematol. 1985 Sep;61(1):177-84