Immunologic Studies of Antihemophilic Factor (AHF, Factor VIII): Cross-Reacting Material in a Genetic Variant of Hemophilia A

Immunologic studies have identified two genetically distinct types of hemophilia A. While a majority of patients apparently fail to synthesize AHF, a variant has been recognized in which a nonfunctional but antigenically cross-reacting AHF-like protein is present. Plasmas from two of twenty-seven families with hemophilia A have a cross-reacting material which inactivates an anticoagulant to AHF. Nonfunctional cross-reacting material was not present in plasmas from six patients with von Willebrand’s disease.