Hemophilia C is caused by a deficiency of coagulation FXI and has autosomal recessive inheritance. It is not completely recessive because if either parent had the defective gene, their offspring might still have a FXI deficiency and excessive bleeding. Acquired hemophilia C can develop due to an immunologic response or an additional disease state, like systemic lupus erythematosus or Noonan syndrome, which causes inhibitors to the FXI protein.
Symptoms and Diagnosis of Hemophilia C
If you have hemophilia C, you likely won’t have spontaneous bleeds, and bleeding tendency can be mild. However, you may have hemorrhaging or prolonged bleeding after a major surgery or a serious enough injury. In addition, you may have some of the following symptoms:
- Oral bleeding, especially after dental surgery or tooth extraction
- Easy bruising
- Blood in the urine
- Post-partum hemorrhage
- Tonsils (excessive bleeding upon removal)
- Bleeding after circumcision
- Hematomas after surgery
- Menorrhagia (heavy or prolonged menstrual bleeding: longer than 5 days, more than 90 ml of bleeding, and/or clots larger than a grape)
- bleeding in the gut (less common)
- blood in the urine (less common)
To diagnose hemophilia C, your hematologist will look for these symptoms, your family history of bleeding (especially if you have known hemophilia C in your lineage), and the results of a clinical evaluation. A coagulation study to diagnose hemophilia C might include the following:
- Activated partial thromboplastin time (aPTT)
- Prothrombin time (PT)
- Bleeding time
- Serum FXI activity
- Thrombin generation tests (still in development)
If you have hemophilia C, your aPTT test will likely be prolonged (taking longer to clot than normal), but your PT tests will likely be normal.
Severity of Hemophilia C
Even among family members, bleeding symptoms for those with hemophilia C vary a lot. Some people with hemophilia C who have very low FXI levels might have mild symptoms and few bleeds, while some people with hemophilia C who have only slightly low FXI levels might have a great deal of bleeding. This is partly why hemophilia C can be difficult to diagnose.