Factor viii-related antigen in the detection of the haemophilia carrier state.

The levels of factor VIII-related antigen (ERA) in normal White females, in White and Black obligatory haemorphilia carriers and in possible haemophilia carriers compared with the functional factor VIII activity. The results obtained compared favourably with those previously reported, in that the obligatory carrier group demonstrated excess antigen compared with functional factor VIII activity. The F VIII/ERA ration obtained for each obligatory carrier was compared statistically with the ratio of normal group. A ratio of 0,65 was the level below which haemophilia carrier status could be predicted within the 95% confidence limits.