Detection of Heterozygotes for Recessive von Willebrand's Disease by the Assay of Antihemophilic-Factor-like Antigen

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Abstract
Asymptomatic relatives of a girl with an extremely severe form of von Willebrand's disease who had consanguineous parents were investigated to determine whether they carried the von Willebrand gene. Bleeding time, procoagulant antihemophilic-factor activity (one-stage method), and antihemophilic-factor-like antigen level (quantitative immunoelectrophoresis) and antibody-neutralizing capacity were estimated in 22 relatives. All showed normal antihemophilic-factor procoagulant activity, but five had significantly low levels of antihemophilic-factor-like antigen. Comparison of the levels of antigen and antihemophilic-factor activity (on the basis of a regression analysis) made it possible to identify three additional carriers of this von Willebrand gene. These results suggest that the antigen is more directly related to the primary gene-product of the von Willebrand locus than antihemophilic-factor activity. (N Engl J Med 289:882–885, 1973)