Unrecognized blood clotting factors

Most clotting factors were initially discovered as agents functionally deficient in the plasmas of rare patients with hereditary coagulation disorders. During 1940s to 1960s, many factors were named by different investigators after the name of the patient who lacked a new factor. Consequently, there were the same factors with different names. To avoid confusion, the International Committee on the nomenclature of clotting factors was founded and discussed the identity or non-identity of clotting factors by specialists. There remain, however, several factors that were not officially authorized. We attempt to review some of these factors that seem to be not identical with any known clotting factors.