Hemophilia is one of the oldest known hereditary diseases and, therefore, has been a rich source of information for genetics. The reports in the older literature must, however, be interpreted with caution, because until recently the diagnosis of hemophilia was often uncertain and sometimes even erroneous. With the development of more definitive tests to study hemophilia and to differentiate it from other bleeding conditions, investigation of various aspects of the disease, especially that of genetics, can now be undertaken with greater assurance of accuracy. The object of the present study is to probe the evidence for the probability that hemophilia may arise de novo, i.e., by mutation.
The tests which were employed were the same as those described in the recent study of hemophilia B.1 Additional procedures and preparation of reagents were carried out as previously outlined.2 In most instances the cases selected for this investigation have