It is now possible to distinguish several disorders of blood coagulation within the condition previously designated as hemophilia, and to identify each as being characterized by defective production of thromboplastin. Whether the latter results from a quantitative deficiency in one of several substances or from the presence of an inhibitor of that substance is debated. Matters of terminology also remain unsettled, and the status of still other hemophilialike disorders awaits confirmation. At present, though, three forms of hemophilia are commonly recognized and usually designated antihemophilic globulin (AHG) deficiency, plasma thromboplastin component (PTC) deficiency, or plasma thromboplastin antecedent (PTA) deficiency.1 It is generally agreed that differentiation of these disorders on clinical grounds alone is virtually impossible and that definitive diagnosis, and to a certain extent rational therapy, rests on the results of certain laboratory tests.
In the light of these findings the present study was undertaken to reevaluate those patients