Haemophilia C

Haemophilia C (also known as plasma thromboplastin antecedent (PTA) deficiency or Rosenthal syndrome) is a mild form of haemophilia affecting both sexes, due to factor XI deficiency. It predominantly occurs in Ashkenazi Jews. It is the fourth most common coagulation disorder after von Willebrand's disease and haemophilia A and B. In the United States, it is thought to affect 1 in 100,000 of the adult population, making it 10% as common as haemophilia A. In terms of the signs/symptoms of haemophilia C, unlike individuals with Haemophilia A and B, people affected by it 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 the following: Haemophilia C is caused by a deficiency of coagulation factor 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 (near 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. Haemophilia C is occasionally observed in individuals with systemic lupus erythematosus, because of inhibitors to the FXI protein. The diagnosis of haemophilia C (factor XI deficiency) is centered on prolonged activated partial thromboplastin time (aPTT).One will find that the factor XI has decreased in the individuals body. In terms of differential diagnosis one must consider: haemophilia A, haemophilia B, lupus anticoagulant and heparin contamination. The prolongation of the activated partial thromboplastin time should completely correct with a 1:1 mixing study with normal plasma if haemophilia C is present; in contrast, if a lupus anticoagulant is present as the cause of a prolonged aPTT, the aPTT will not correct with a 1:1 mixing study.