Hemophilia A is an inherited condition. It results from a lack of an important blood clotting protein.
An individual with hemophilia A has poor blood clotting. The missing clotting protein, which is called factor VIII, causes the problem. Hemophilia A is one of the most common inherited bleeding disorders. It affects primarily men.
Inheriting an abnormal X chromosome usually causes hemophilia. This chromosome is usually passed down from the mother. Men have only one X chromosome, while women normally have two. This means that a woman usually has to inherit two abnormal X-chromosomes, while men only need one, to get the disease. Because of this, males more commonly get hemophilia.