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Haemophilia A
What is haemophilia A?
Haemophilia A is an inherited bleeding disorder that makes it difficult for blood to clot properly.[1]
In a healthy person, proteins called clotting factors work together to form a blood clot and help stop bleeding.[2] People with haemophilia A do not have enough of a clotting factor called factor VIII.[1] As a result, bleeding can occur from injuries, surgery or even without any apparent cause, and it takes longer to stop.[1]
The seriousness of haemophilia depends on how much factor VIII is present in a person’s blood.[3] When the level of the factor is lower, the chances of bleeding are higher, which may cause serious health problems.[3]
What causes haemophilia A?
Haemophilia A is an inherited condition that occurs when a specific gene (F8) is missing or defective. This gene causes a problem with the clotting factor VIII, which is needed to stop bleeding.[1] It is passed down through the X chromosome.[1]
Males typically have one X and one Y chromosome, while females typically have two X chromosomes.[3] When females carry this gene, there is a 50/50 chance of passing it on to their children. If the gene is passed onto a male child, they will have the disease.[1] If the gene is passed on to a female child, they will become a carrier.[1] However, the term carrier can be misleading as some female carriers may have reduced levels of Factor VIII, showing haemophilia symptoms.[4]
If the female parent doesn’t carry the haemophilia gene, the male parent with haemophilia A cannot pass it on to their male children, but their female children will carry the gene.[1,5] This pattern of inheritance is known as sex- or X-linked recessive.[4]
Cases with no family history
Sometimes, a male child can be born with haemophilia even if nobody in the family had it before.[5] In these situations, it is believed that the gene mutation occurred spontaneously in the child's female parent, female grandparent or female great-grandparent.[5] This means that the condition appeared in the family for the first time, and no male member had inherited it previously.[5] Some studies have found that in up to 1 out of 3 new cases of haemophilia, there is no known history of the condition in the family.[5]
What are the symptoms of haemophilia A?
Haemophilia A symptoms can be similar to other conditions, so always check with a doctor for a proper diagnosis.[3,4,6] Signs can vary from mild to severe, depending on the severity of the condition.
- People with haemophilia A bleed longer than usual.
- Bleeding from minor cuts and scratches can usually be treated by applying a little pressure.
- However, prolonged bleeding may occur following larger cuts or minor surgeries such as removal of teeth or circumcision (surgery to remove the hood of skin, called the foreskin, covering the head of the penis, in male babies), that can last for several days.
- When children affected with haemophilia A begin to crawl or walk, bruises are commonly seen on their knees and elbows, if they fall or roll onto a hard toy or surface. Bruises may appear on their buttocks if they fall or sit down suddenly.
- In severe cases of haemophilia A, internal bleeding into joints and muscles may occur spontaneously, especially in the knees, elbows, and ankles.
- When there is bleeding into a joint or a muscle, it leads to painful, stiff and swollen joints causing difficulty in using the joint or muscle.
- Developing clumps of blood under the skin (known as ‘hematomas’) after getting an injection.
How is haemophilia A diagnosed?
If your doctor thinks you might have haemophilia A, they will ask questions about symptoms, examine your body for bruises or lesions and refer you to a blood specialist (haematologist), who will run certain tests. These include:[7,8]
- Complete blood count (CBC): This test measures and examines different types of blood cells.
- Prothrombin time (PT) test: This test determines how quickly your blood clots.
- Activated partial thromboplastin time (APTT) test: Another blood test that measures the time it takes for blood to clot.
- Fibrinogen test: This test measures the level of a blood protein called fibrinogen, which plays a role in clotting.
- Clotting factor test: This blood test reveals the specific type and severity of haemophilia.
- Genetic or DNA testing: This testing is performed to check for abnormal genes associated with haemophilia.
What treatment options are available for haemophilia A?
At the moment there is no cure for haemophilia A, so treatments are used to relieve symptoms in order to improve quality of life. The main treatments used for haemophilia A are:
Clotting factor replacement
One common treatment for haemophilia A is receiving injections in the vein (intravenous) of the missing clotting factor (which can be similar to the natural FVIII, called recombinant, or an actual human molecule coming from blood), which helps the blood to clot. These injections can be given regularly to prevent bleeding episodes (prophylaxis) or when there is bleeding due to an injury or surgery (on demand).[9]
Non-factor replacement therapies
Non-factor replacement products act like factor VIII. They are given as injections under the skin (subcutaneous) to prevent (prophylaxis) or reduce bleeding and can be used by patients even if they develop an inhibitor (antibody against FVIII that makes clotting replacement factors less effective).[9] Clotting factor replacement would be needed to treat bleeds.
Gene therapy
Gene therapy for haemophilia A is a promising approach that has made significant progress, and is available to a portion of patients.[12] It involves introducing a healthy copy of the missing gene into the body so that it can produce enough factor VIII on its own.[9] Scientists are using certain viruses to deliver the healthy gene into the body, and early studies have shown positive results.[9]
Antifibrinolytic agents
Antifibrinolytic agents may be used as supportive therapy in patients with hemophilia A to prevent the breakdown of fibrin in blood clots (fibrinolysis), thereby reducing the risk of bleeding after dental procedures or injuries.[10]
What is the outlook for a person with haemophilia A?
Persons affected with haemophilia A may lead a poor quality of life due to prolonged pain and problems with limb movement.[11] Psychosocial issues may also develop due to inability to attend school or work; limited participation in sports activities; reduced social life; negative self-perceptions of body image, masculinity, or self-esteem; limited physical flexibility; and inability to perform reliably at work causing loss of job and finances.[11]
Clinical trials (which can also be called ‘research studies’) are designed to look at how safe experimental drugs are and how well they work. Researchers are working hard to learn more about haemophilia A and advances in treatment including gene therapy.[9]
To learn more about clinical trials, please click here.
If you would like to know more about Roche sponsored clinical trials, visit the Roche ForPatients clinical trials page: Link
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Zobacz powiązane badaniaPozostałe zasoby
- Salen P, Babiker HM. Hemophilia A. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023 Feb 5. Available from: Bookshelf ID: NBK470265 https://www.ncbi.nlm.nih.gov/books/NBK470265/ 05.Feb.2023
- MedlinePlus. Coagulation Factor Tests. Accessed on 2023 June 22. Available from: https://medlineplus.gov/lab-tests/coagulation-factor-tests 22.Jun.2023
- Centers for Disease Control and Prevention. What is Hemophilia? Accessed on 2023 June 22. Available from: https://www.cdc.gov/ncbddd/hemophilia/facts.html 22.Jun.2023
- What causes Haemophilia? The Haemophilia Society. Accessed on 2023 September 12. Available from: https://haemophilia.org.uk/bleeding-disorders/haemophilia-a-and-b/what-causes-haemophilia/ 12.Sep.2023
- National Health Service. Causes of haemophilia. Accessed on 2023 June 22. Available from: https://www.nhs.uk/conditions/haemophilia/causes/ 22.Jun.2023
- Hemophilia. World Federation of Hemophilia. eLearning WFH Educational Platform. Accessed on 2023 September 12. Available from: https://elearning.wfh.org/elearning-centres/hemophilia/ 12.Sep.2023
- Cleveland Clinic. Hemophilia A. Accessed on 2023 June 22. Available from: https://my.clevelandclinic.org/health/diseases/23197-hemophilia-a 22.Jun.2023
- Johns Hopkins Medicine. Hemophilia in Children. Accessed on 2023 June 22. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/hemophilia-in-children 22.Jun.2023
- Castaman G, Di Minno G, De Cristofaro R, Peyvandi F. The Arrival of Gene Therapy for Patients with Hemophilia A. Int J Mol Sci. 2022 Sep 6;23(18):10228. Published 2022 Sep 6. Available from doi: 10.3390/ijms231810228 https://www.mdpi.com/1422-0067/23/18/10228 06.Sep.2023
- Joel L. Moake. Hemophilia. MSD Manual Professional Version. Accessed on 2023 September 12. Available from: https://www.msdmanuals.com/en-gb/professional/hematology-and-oncology/coagulation-disorders/hemophilia 12.Sep.2023
- WFH Guidelines for the management of hemophilia. 3rd Edition. World Federation of Hemophilia. Accessed on 2023 September 12. Available from https://www1.wfh.org/publications/files/pdf-1863.pdf 12.Sep.2023
- Chou SC, Hsu YC, Lin SW. Gene therapy for hemophilia, a clinical viewpoint [published online ahead of print, 2023 May 18]. J Formos Med Assoc. 2023;S0929-6646(23)00159-6. doi:10.1016/j.jfma.2023.05.008