What causes hemophilia?

Acquired hemophilia is a rare variety of the condition that occurs when a person's immune system attacks clotting factors in the blood. It can be associated with: Pregnancy; Autoimmune conditions; Cancer; Multiple sclerosis; Hemophilia inheritance. In the most common types of hemophilia, the faulty gene is located on the X chromosome. read more

Hemophilia A is caused by a mutation in the gene for factor VIII, so there is deficiency of this clotting factor. Hemophilia B (also called Christmas disease) results from a deficiency of factor IX due to a mutation in the corresponding gene. A condition referred to as hemophilia C involves a deficiency of clotting factor XI. read more

Hemophilia A runs in families. It's usually diagnosed in babies, toddlers, or young children. Causes. Hemophilia A comes from your genes. You can inherit it from your parents. Or it can happen if a certain gene changes before you're born. This change is called a mutation. There is a rare, dangerous form of hemophilia A that is not inherited. read more