High Quality Content by WIKIPEDIA articles! Haemophilia C is a mild form of haemophilia affecting both sexes. However, it predominantly occurs in Jews of Ashkenazi descent. It is the fourth most common coagulation disorder after von Willebrand`s disease and haemophilia A and B. In the USA it is thought to affect 1 in 100,000 of the adult population, making it 10% as common as haemophilia A.