Heredity and Coagulation Studies in Ten Families with Factor XI (Plasma Thromboplastin Antecedent) Deficiency

Rosenthal, Dreskin and Rosenthal (1953) described a familial haemorrhagic disorder due to plasma thromboplastin antecedent (PTA) deficiency. Further studies have established the properties of this factor and its action in the early phase of thromboplastin generation (Rosenthal, 1954; Rosenthal, Dreskin and Rosenthal, 1955; Ramot, Angelopoulos and Singer, 1955; Campbell, Mednikoff and Dameshek, 1957; Cavins and Wall, 1960). The mode of hereditary transmission of this deficiency has been discussed by various authors (Cavins and Wall, 1960; Campbell et al., 1957; Rosenthal et al., 1955). Recently Rapaport, Proctor, Patch and Yettra (1961), using a quantitative assay of PTA, suggested that this deficiency is transmitted by an intermediate gene, which produces major PTA deficiency in the homozygote and minor PTA deficiency in the heterozygote. In the present communication, 10 families with PTA deficiency will be described and the mode of its inheritance will be discussed.