The Blood Clotting Process and Its Breakdown
To understand what factor is deficient in haemophilia, it is essential to first grasp the basic mechanism of blood clotting. When a blood vessel is injured, a complex sequence of events, known as the coagulation cascade, is triggered to form a clot and stop the bleeding. This cascade involves a series of blood proteins called clotting factors. Each factor works in a specific order, activating the next in the sequence until a solid fibrin clot is formed to plug the wound. In individuals with haemophilia, this process is interrupted because one of these crucial clotting factors is either missing entirely or does not function correctly.
Factor VIII in Haemophilia A
The most common type of haemophilia, known as haemophilia A, or classic haemophilia, is caused by a lack or low level of clotting factor VIII. This is the more prevalent form, accounting for roughly 80% of all haemophilia cases. Without enough functional factor VIII, the coagulation cascade is severely impaired, resulting in delayed and prolonged bleeding episodes. The gene responsible for producing factor VIII is located on the X chromosome, which explains the characteristic inheritance pattern of this disorder. The severity of haemophilia A—mild, moderate, or severe—is determined by the level of factor VIII activity in the blood. Even with minor trauma, a person with severe haemophilia A is at high risk for spontaneous and prolonged bleeding into joints, muscles, or internal organs.
Factor IX in Haemophilia B
The second most common type, haemophilia B, also known as Christmas disease, involves a deficiency of clotting factor IX. Similar to haemophilia A, the gene for factor IX is located on the X chromosome, so it also follows the same X-linked inheritance pattern. A person with haemophilia B has low or insufficient levels of factor IX, leading to improper clot formation. While clinically indistinguishable from haemophilia A in terms of symptoms, it is crucial to determine which factor is deficient for proper treatment. People with haemophilia B can also be classified as having mild, moderate, or severe forms based on their factor IX activity levels.
Comparison of Haemophilia A and B
| Feature | Haemophilia A | Haemophilia B |
|---|---|---|
| Deficient Factor | Clotting Factor VIII (FVIII) | Clotting Factor IX (FIX) |
| Alternate Name | Classic Haemophilia | Christmas Disease |
| Incidence | Approximately 1 in 5,000 male births | Approximately 1 in 30,000 male births |
| Prevalence | More common | Less common |
| Inheritance | X-linked recessive | X-linked recessive |
| Clinical Picture | Clinically indistinguishable from Haemophilia B | Clinically indistinguishable from Haemophilia A |
Symptoms and Complications of Factor Deficiency
The symptoms of haemophilia are directly tied to the severity of the factor deficiency. In mild cases, a person may only experience unusual bleeding after a major surgery or significant trauma. Moderate cases might see bleeding episodes after minor injuries. However, individuals with severe haemophilia can experience spontaneous bleeding without any apparent cause. The most common signs and symptoms include:
- Bleeding into joints, leading to pain, swelling, and long-term joint damage (haemophilic arthropathy).
- Bleeding into muscles and soft tissues, resulting in a deep bruise or hematoma.
- Excessive bleeding from the mouth and gums.
- Prolonged bleeding after a cut, tooth extraction, or surgery.
- Blood in the urine or stool.
- Frequent and difficult-to-stop nosebleeds.
Diagnosis and Testing
Diagnosing haemophilia typically involves a physical examination and a series of blood tests. A doctor may suspect haemophilia based on a family history of bleeding disorders or observing a patient’s unusual bleeding patterns. Laboratory tests measure the time it takes for blood to clot and the levels of specific clotting factors. For example, a doctor will test the levels of both factor VIII and factor IX to confirm the specific type of haemophilia. Genetic testing is also available to identify the mutation responsible for the condition, which can be useful for predicting severity and for family planning.
Treatment and Management
While there is no cure for haemophilia, effective treatments are available to manage the condition. The primary goal is to replace the missing clotting factor. This is often done through regular infusions of clotting factor concentrates, a practice known as prophylaxis, which helps prevent bleeding episodes from occurring. For mild haemophilia A, a medication called desmopressin can sometimes be used to stimulate the release of stored factor VIII. In recent years, advanced therapies have emerged, including gene therapy and non-factor replacement therapies, offering new hope and improved quality of life for many patients.
Managing Haemophilia Daily
Successfully managing haemophilia involves a multi-pronged approach that includes more than just factor replacement. It requires a dedicated healthcare team, patient education, and a proactive mindset. Regular exercise, with supervision, is crucial for strengthening joints and muscles, which can reduce the risk of bleeds. Physical therapy is also a vital component for those with joint damage. Avoiding certain activities, such as contact sports, and being prepared for bleeding episodes are also key strategies for living a full and active life with haemophilia.
- Treatment Options for Haemophilia:
- Replacement Therapy: Infusions of factor VIII or factor IX concentrate.
- Desmopressin (DDAVP): A synthetic hormone for managing mild haemophilia A.
- Non-Factor Therapies: Innovative drugs that bypass the need for the missing factor.
- Physical Therapy: To rehabilitate joints affected by bleeds.
- Gene Therapy: A treatment option currently in development or recently approved for some types of haemophilia.
For more information on the latest advancements and resources, the National Bleeding Disorders Foundation (NBDF) provides valuable guidance: https://www.bleeding.org.
