Problems in the detection of carriers of haemophilia A

sYNoPsIs Factor VIII activity and factor VIII related-or Willebrand-antigen were studied in 49 known carriers of haemophilia A and 31 normal women, and the data were analysed by four statisti-cal approaches. Sixteen per cent of normals and 18 % of carriers were misclassified, overlapping with the other group. Although the percentage of carriers detected is higher when taking into account the results of both biological and immunological factor VIII, it is lower than others recently reported, and the discrepan-cies between the results obtained are discussed. Haemophilia A is X-chromosome linked and is characterized by decreased plasma factor VIII (anti-haemophilic factor A) levels as measured by specific clotting assays. The detection of carriers of haemo-philia A remains a difficult and still controversial problem. Previous attempts at defining them have depended upon the measurement of factor VIII clotting activity (Soulier and Josso, 1966). It has bee