Abstract
Four cases with congenital factor XI (PTA) deficiency from a Korean family were reported. An 11 year old girl with nasal bleeding was found to have prolonged whole blood clotting time and plasma recalcification time, abnormal prothrombin consumption test and abnormal thromboplastin generation test.
The factor XI activity examined using PTA deficient plasma (DADE) as a substrate was around 20%. Other plasmatic clotting factors were within normal range. The patient's father, mother and younger sister (7 year old) showed 36, 44 and 32% of factor XI activity, respectively. All of them have had mild hemorrhagic tendencies such as nasal and gingival bleeding.
With these laboratory findings, four patients were diagnosed to be factor XI deficiency, and were classified as a minor deficiency type under Rapaport's criteria.
Following a single fresh plasma infusion of 5 U/kg of body weight, the factor XI activity was elevated from 23% to 44% and returned to the preinfusion level within 24 hours. But plasma recalcification time and activated partial thromboplastin time were kept normal for 48 to 72 hours after infusion.
