Histocompatibility antigen patterns in haemophilic patients with factor VIII antibodies.

A number of studies suggest that there is a genetic basis for the formation by some haemophilia A patients of antibodies that inactivate factor VIII. In our study, human leucocyte antigen (HLA)-A, B, C, DR and DQ typing was carried out for 44 haemophilia A patients, including 16 who had developed an antibody to factor VIII. In contrast to previous reports, we found no association between HLA-DR antigens and haemophilia A per se or the formation of a factor VIII inhibitor. However, there was an absence of HLA-Cw5 in the 16 haemophilic patients who had formed an antibody to factor VIII. This finding, consistent with a previous report, identified a statistically significant difference in HLA-Cw5 frequency when the inhibitor patient group was compared to multi-transfused haemophilic patients who had no inhibitor (11/28).