2 POPULATIONS OF FACTOR-VIII-RELATED ANTIGEN IN A FAMILY WITH VONWILLEBRAND DISEASE

The factor VIII-related antigen in a patient with von Willebrand''s disease showed increased anodal mobility on 2-dimensional immunoelectrophoresis. The antigen present in several of this patient''s relatives showed 2 distinct peaks, 1 in the normal position and 1 similar to that of the patient. Very little of the patient''s antigen could be recovered from ethanol precipitates or cryoprecipitates of whole plasma. Only the slower component could be recovered from the precipitates prepared from plasma of these family members showing 2 populations of antigen, the faster moving antigen remaining in the supernatant. This antigen of increased mobility corresponded very closely to that remaining in the supernatant of normal plasma, following similar fractionation procedures. The factor VIII-related antigen in some variant forms of von Willebrand''s disease apparently is a normal component of plasma, present in increased amounts.