Hageman Trait (Factor XII Deficiency): A Probable Second Genotype Inherited as an Autosomal Dominant Characteristic

A family is described in which Hageman trait appeared to be inherited in an autosomal dominant manner in contrast to previously reported families in which the disorder behaves as an autosomal recessive characteristic. Immunologic studies suggested that the molecular defect was similar to that of the autosomal recessive form and consisted of deficiency of antigens related to Hageman factor.