Haemophilia C (also known as plasma thromboplastin antecedent (PTA) deficiency or Rosenthal syndrome) 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 haemophiliaA 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.
It is caused by a deficiency of coagulationfactor XI and is distinguished from haemophilia A and B by the fact it does not lead to bleeding into the joints. Furthermore, it has autosomal recessive inheritance, since the gene for factor XI is located on chromosome 4 (close to the prekallikrein gene); and it is not completely recessive, individuals who are heterozygous also show increased bleeding. Many mutations exist, and the bleeding risk is not always influenced by the severity of the deficiency. Treatment is usually not necessary, except in relation to operations, leading to many of those having the condition not being aware of it. In these cases, fresh frozen plasma or recombinant factor XI may be used, but only if necessary. The afflicted may often suffer nosebleeds, and females can experience heavy menstrual bleeding. Heavy menstrual bleeding can be avoided by taking birth control such as: IUDs and oral or injected contraceptives to increase coagulation ability by adjusting hormones to levels similar to pregnancy. Haemophilia C was first discovered in a young Ashkenazic Jewish American in the 1950s.
Unlike individuals with Haemophilia A and B, patients affected by haemophilia C are not ones to bleed spontaneously. In these cases, haemorrhages tend to happen after a major surgery or injury. However, people affected with Haemophilia C might experience symptoms closely related to those of other forms of haemophilia such as:
Traces of blood in the urine.
Heavy menstrual bleeding in females.
The drug Cyklokapron is often used for both treatment after an incident of bleeding and as a preventative measure to avoid excessive bleeding during oral surgery.