Hemophilia B can be divided into at least two mutant forms different from the mild, moderate, and severe categories previously described. In about 90% of hemophilia B patients, PTC-inhibitor-neutralizing activity is reduced in proportion to PTC clotting activity. In about 10% of the patients, PTC-inhibitor-neutralizing activity is fully effective, whereas PTC clotting activity is reduced. Extensive pedigree studies indicate that the presence or absence of inhibitor-neutralizing activity is genetically determined. It is suggested that those hemophilia B mutants with decreased inhibitor-neutralizing material produce decreased amounts of PTC-protein. It is further suggested that those with normal levels of inhibitor-neutralizing material produce normal amounts of PTC-protein, which is structurally altered so as to lose procoagulant activity but which retains inhibitor-neutralizing activity. The latter group may be analogous to CRM+ mutants described in bacteria and Neurospora.
Harold R. Roberts, James E. Grizzle, William D. McLester, George D. Penick
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.