Plasma thromboplastin antecedent (PTA) deficiency; clinical, coagulation, therapeutic and hereditary aspects of a new hemophilia-like disease.

1. An analysis of the original PTA deficient family, including coagulation studies performed upon 13 members comprising 4 generations, has been presented. 2. PTA deficiency is transmitted as an autosomal dominant trait with a probable high degree of penetrance and variable expression of the gene. 3. PTA deficiency can occur its varying degrees ranging from a severe form with prolonged clotting time and markedly abnormal heparin clotting time and prothrombin utilization to a mild form manifesting a normal clotting time and slightly impaired prothrombin utiliztition. 4. Studies on the treatment of PTA deficiency reveal that the defect is corrected by the administration of stored plasma with the effect gradually disappearing over the period of one week. 5. Various properties of PTA are discussed and compared with AHG and PTC.