[Factor XI deficiency--a rare coagulopathy in the GDR].

The authors report on a kin affected with PTA deficiency. The person with homozygous features and a factor XI content below 1% is solely characterized by prolongations of ART and PTT, which were clinically correlated as severe secondary hemorrhages after injuries and surgical treatments. Three heterozygous persons had normal results in global and group tests at 40-50% of factor XI with objectively unambiguous bleeding episodes being absent. As a peculiarity of the recessive heredity of this kin the marriage of two descendants in the fourth generation deserves to be mentioned.