What Is the Missing Factor in Hemophilia C?
Hemophilia C, also known as factor XI deficiency, is a rare inherited bleeding disorder caused by a deficiency of clotting factor XI. Unlike hemophilia A and B, which primarily affect males due to X-linked inheritance, hemophilia C follows an autosomal inheritance pattern—meaning both men and women are equally likely to be affected. This condition is considered incompletely recessive, so even carriers (heterozygotes) may exhibit mild symptoms under certain circumstances.
Understanding the Genetics Behind Hemophilia C
The root cause of hemophilia C lies in mutations within the F11 gene located on chromosome 4, which is responsible for producing factor XI—a crucial protein involved in the intrinsic pathway of blood coagulation. Because it's inherited in an autosomal manner, family history plays a significant role in diagnosis. Individuals with one defective copy may not show obvious symptoms but can still pass the gene to their offspring. In some cases, people with two defective copies experience more noticeable bleeding tendencies.
Bleeding Symptoms and Clinical Presentation
Compared to other forms of hemophilia, Hemophilia C typically results in milder bleeding episodes. Many individuals remain asymptomatic until exposed to trauma, surgery, or dental procedures such as tooth extraction. Post-surgical or post-dental bleeding is the most common clinical manifestation. Nosebleeds, heavy menstrual periods in women, and prolonged bleeding after injuries may also occur, though spontaneous bleeding into joints or muscles (common in severe hemophilia A/B) is rare in this form.
Associated Conditions and Coexisting Disorders
It's important to note that factor XI deficiency can sometimes coexist with other congenital coagulation disorders, complicating diagnosis and management. For example, patients might have concurrent deficiencies in factors IX or VII, requiring comprehensive laboratory evaluation. Accurate diagnosis involves measuring activated partial thromboplastin time (aPTT), which is often prolonged, followed by specific factor XI activity assays.
Treatment Options and Management Strategies
The primary approach to managing hemophilia C is replacement therapy. Since fresh frozen plasma (FFP) contains factor XI, it is commonly used to control or prevent bleeding during surgical interventions. In some cases, prophylactic infusion of plasma-derived factor XI concentrate may be recommended before high-risk procedures. Cryoprecipitate, while rich in fibrinogen, contains lower levels of factor XI and is less preferred unless other options aren't available.
Antifibrinolytic agents like tranexamic acid are also beneficial, especially for mucosal bleeding or dental work, as they help stabilize clots and reduce blood loss. However, treatment must be personalized based on the patient's bleeding history, factor level, and planned procedure.
Living with Hemophilia C: Prognosis and Awareness
Most individuals with hemophilia C lead normal lives with proper medical guidance. The key is awareness—both among patients and healthcare providers—about the potential for increased bleeding risk during invasive procedures. Genetic counseling is advised for families with a known history, enabling informed decisions about family planning and early diagnosis.
In summary, hemophilia C, though rare, requires careful evaluation and tailored management. With advances in diagnostic testing and targeted therapies, patients can achieve excellent outcomes when care is proactive and well-coordinated.