Hemophilia A results from a deficiency (lack) of clotting factor VIII.
The disorder is caused by an inherited X-linked recessive trait, with the defective gene located on the X chromosome. Females have two copies of the X chromosome, so if the factor VIII gene on one chromosome doesn't work, the gene on the other chromosome can do the job of making enough factor VIII. Males, however, have only one X chromosome, so if the factor VIII gene on that chromosome is broken, they will have hemophilia A. Thus, most people with hemophilia A are male.
If a woman has a defective factor VIII gene, she is considered a carrier. This means the defective gene can be passed down to her children. In a woman who carries the defective gene, any of her male children will have a 50% chance of having hemophilia A, while any of her female children will have a 50% chance of being a carrier. All female children of men with hemophilia carry the defective gene. Genetic testing is available for concerned parents.
The severity of symptoms can vary. Severe forms become apparent early on. Bleeding is the main symptom of the disease and sometimes, though not always, occurs if an infant is circumcised. Additional bleeding problems are seen when the infant starts crawling and walking.
Hemophilia B (5 images)(Doctor-Reviewed information)
Hemophilia B is a hereditary blood coagulation disorder. It is caused by a deficiency of a blood plasma protein called factor IX. Reviewer: Stephen Grund, MD, PhD, Chief of Hematology/Oncology and Director of the George Bray Cancer Center at New Britain General Hospital, New Britain, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/21/2008
Von Willebrand disease (2 images)(Doctor-Reviewed information)
Von Willebrand disease is the most common hereditary bleeding disorder.Von Willebrand disease is caused by a deficiency of von Willebrand factor. Von Willebrand factor helps blood platelets clump together and stick to the blood vessel wall, which ...Reviewer: Stephen Grund, M.D. Ph.D., Chief of Hematology/Oncology and Director of the George Bray Cancer Center at New Britain General Hospital, New Britain, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/21/2008
Platelet count(Doctor-Reviewed information)
A platelet count is a test to measure how many platelets you have in your blood. Platelets help the blood clot. Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Date: 02/21/2009
Vitamin K (2 images)(Doctor-Reviewed information)
Vitamin K is a fat-soluble vitamin that plays an important role in blood clotting. The body can store fat-soluble vitamins in fatty tissue.Vitamin K is known as the clotting vitamin, because without it blood would not clot. Reviewer: Linda Vorvick, MD, Family Physician, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/07/2009
Bleeding disorders(Doctor-Reviewed information)
Bleeding disorders are a group of conditions in which there is a problem with the body''s blood clotting process. These disorders can lead to heavy and prolonged bleeding after an injury. Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 03/02/2009
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