Factor VII deficiency: immunological characterization of genetic variants and detection of carriers.

Twenty-one patients with congenital factor VII deficiency belonging to 16 different kindreds were investigated. The existence of three immunochemical variants on the ground of factor VII activity (VII:C) and factor VII-related antigen (VII:Ag) levels (VII-, VII+ and VIIR) was established. There was no correlation between the presence of factor VII:Ag and either the clinical picture or the specific function as studied with the Km calculations. Genetically the model of inheritance is the same whatever the immunological variant, but the identification of carriers is simplified when the presence of factor VII-related antigen is assayed throughout a kindred.