[DNA analysis in the inhibitor phenotype of the hemophilias].

In spite of many reports of DNA abnormalities in the hemophilias, the cause of the inhibitor phenotype in the hemophilias has not yet well known. For a better understanding of this problem, we have analyzed the factor VIII and IX gene in the hemophilia A and B patients with inhibitor we are following. In four out of eight hemophilia A inhibitor patients have shown partial gene deletions. In some literature, about 60% of hemophila A inhibitor patients have shown gross gene deletions. It seems likely that the titer of inhibitor in the hemophila A patients who have gross deletions are relatively high. In hemophila B inhibitor patients, on the other hand, not only gross gene deletion but also point mutations or small nucleotide deletions is predisposed to development of inhibitors. We believe that the characterization of both the gene defects and the epitope specificity of the antibodies against factor VIII or IX found in inhibitor patients would clarify the situation and reveal important immunological features of these coagulation factors.