Biochemical characterisation of the haemophilias on the Witwatersrand.

Blood samples obtained from patients on the Witwatersrand with haemophilia A, haemophilia B and von Willebrand disease were analysed. Factor activities were assayed by conventional methods. Immunoradiometric assay using labelled monoclonal anti-VIIIC:Ag was developed to assay factor VIIIC:Ag in haemophilia A. Factor IX:Ag levels were determined by a commercial ELISA kit. Multimer pattern analysis of von Willebrand factor was performed by agarose gel electrophoresis and Western blotting. In 43 patients haemophilia A was severe, in 8 it was moderate and in 2 it was mild. Factor VIIIC:Ag was undetected in 36 haemophiliacs (CRM-) while VIIIC:Ag was detected in levels exceeding or correlating with those of VIII:C in 17 cases (CRM+). Four severe, CRM- haemophiliacs were found to have inhibitors. An assay of IX:Ag in 6 severely and 2 moderately affected patients with haemophilia B revealed 6 to be CRM- while 2 were CRM+. Multimer pattern analysis was performed on 11 von Willebrand disease patients, of which 5 were type I, 5 were type II and 1 was type III. More informative techniques for the diagnosis and classification of haemophilia are now available. In addition, these results will assist in further molecular studies of these disorders.