There are ten clotting factors necessary in forming a blood clot. Deficiencies in Factors VIII and IX are found in hemophilia and von Willebrand, but the others are less known and are rare. Deficiencies in eight of the lesser known coagulation factors (Factors I, II, V, VII, X, XI, XII and XIII) have only been discovered within the last 40 years.
In most cases, rare factor deficiencies occur equally among men and women and not all factor deficiencies have the same severity, with some not even needing treatment. Those who do need treatment often have to take fresh frozen plasma to help their blood clot.