What is Hemophilia type A
Hemophilia A is a rare genetic disorder caused by missing or defective factor VIII (FVIII) clotting protein in the blood. It is usually inherited, but in about one-third of known cases, it’s caused by a spontaneous genetic mutation.
Anyone can be diagnosed with hemophilia A. More than half of all patients eventually develop a severe form of the disease.
Genetics of hemophilia type A
Hemophilia A is inherited in an X-linked recessive pattern, meaning that two hemophilia-carrying X chromosomes must be inherited for the disease to be active in women, but in men, only one X chromosome is needed.
Females inherit two X chromosomes, one from their mother and one from their father (XX). Males inherit an X chromosome from their mother and a Y chromosome from their father (XY). This means that if a son inherits an X chromosome from his mother who carries hemophilia, he will have hemophilia. But because women receive two X chromosomes, they will develop the disease only if both chromosomes carry the defective gene.
More information about the genetics of hemophilia A is available in Genetics Home Reference’s Genetic Consultation Handbook.
The following online resources are also helpful:
- Find U.S. and foreign genetics and prenatal diagnostic clinics through GeneTests’ directory;
- Find U.S. and foreign genetic counseling services through the National Society of Genetic Counselors directory;
- Find U.S. genetics clinics through the American College of Medical Genetics database;
- Find geneticists in and outside your country, including researchers who do not provide medical care, through the American Society of Human Genetics database;
Stages and symptoms of hemophilia type A
Hemophilia A has three stages: mild (6-49 percent clotting factor VIII in the blood); moderate (1-5 percent factor VIII); and severe (less than 1 percent factor VIII).
Hemophilia A patients might bleed longer than other people, internally or externally, depending on how much clotting factor VIII is in their blood.
People with this type of hemophilia generally bleed only after serious injury or trauma, and often the disease is diagnosed after a symptomatic event, which may only occur in adulthood. For example, women who often experience heavy menstrual periods can hemorrhage after giving birth.
Moderate hemophilia patients tend to have more frequent bleeding episodes after minor injuries, or even spontaneously. In severe cases, bleeding may occur spontaneously in the joints and muscles.
Testing for hemophilia type A
Hemophilia A should be diagnosed and treated at a specialized hemophilia center. Tests that evaluate clotting time and a patient’s ability to form a clot may be ordered to assess the type and severity.
The Genetic Testing Registry (GTR) provides information about genetic tests for this condition. The registry targets healthcare providers and researchers, so patients and consumers with specific questions should ask their healthcare provider or physician.
Therapies for hemophilia type A
People with hemophilia A require lifelong care, preferably at a specialized treatment center.
The replacement therapy approach — in which the missing clotting factor VIII is replaced to prevent complications — generally works well. Replacement therapy is generally used as “episodic therapy” to treat patients with mild or moderate hemophilia A.
Some people with mild forms of the disease may also be treated with desmopressin (DDAVP), which raises FVIII levels in the blood. Antifibrinolytics, which slow the breakdown of clotting factors in the blood, also are used to treat milder forms of the disorder.
Patients with severe hemophilia A might receive periodic factor VIII infusions to prevent bleeding, in an approach referred to as prophylactic therapy.
Patients can administer these infusions at home themselves if they receive training. This is important for people with severe forms of the disease, because the infusion works best within one hour of a bleeding episode. The goal is to stop the bleeding as soon as possible.
Treatments for hemophilia type A
Here is a list of U.S. Food and Drug Administration-approved products for the treatment of hemophilia A:
- Eloctate (antihemophilic factor [recombinant], Fc Fusion Protein) – Eloctate is approved for the treatment of adults and children with hemophilia A, particularly to control and prevent bleeding episodes, for perioperative management, and for routine prophylaxis to prevent or reduce the frequency of bleeding episodes. It’s manufactured by Biogen.
- Kogenate FS (antihemophilic factor [recombinant]) – Kogenate FS is approved for the treatment and prophylaxis of bleeding in patients with hemophilia A – not von Willebrand’s disease. It is manufactured by Bayer.
- NovoSeven RT (coagulation factor 7a [recombinant]) – NovoSeven is approved for the treatment of bleeding episodes in patients with Factor VII deficiency as well as for the treatment and perioperative management of Glanzmann’s thrombasthenia refractory to platelet transfusions, with or without antibodies to platelets. It is manufactured by Novo Nordisk.
- ReFacto (antihemophilic factor [recombinant]) – ReFacto is approved for the control and prevention of hemorrhagic episodes and for surgical prophylaxis in patients with hemophilia A. It’s a Wyeth Pharmaceuticals product.
- Stimate (desmopressin acetate) – Stimate nasal spray is approved for the treatment of patients with hemophilia A or von Willebrand’s disease (type I) whose factor VIII coagulant activity level is greater than 5 percent. It’s manufactured by CSL Behring.
Hemophilia News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.