Hemophilia A, a deficiency in clotting factor VIII, is a hereditary disorder in which the clotting ability of the blood is impaired and excessive bleeding results. Uncontrolled internal bleeding can result in pain, swelling, and permanent damage, especially to joints and muscles.

Severity of symptoms can vary, and severe forms become apparent early on. Prolonged bleeding is the hallmark of hemophilia A and typically occurs when an infant is circumcised. Additional bleeding manifestations make their appearance when the infant becomes mobile.

Mild cases may go unnoticed until later in life when there is excessive bleeding and clotting problems in response to surgery or trauma. Internal bleeding may happen anywhere, and bleeding into joints is common.

The incidence of hemophilia A is 1 out of 10,000 live male births. About 17,000 Americans have hemophilia. Women may have it, but it’s very rare. With treatment and management, the outcome is good. Most men with hemophilia are able to lead relatively normal lives.

Inheritance Pattern

Hemophilia A is caused by an inherited sex-linked recessive trait with the defective gene located on the X chromosome. Females are carriers of this trait. Fifty percent of the male offspring of female carriers have the disease and 50% of their female offspring are carriers. All female children of a male with hemophilia are carriers of the trait. One third of all cases of hemophilia A occur when there is no family history of the disorder. In these cases, hemophilia develops as the result of a new or spontaneous gene mutation.

Genetic counseling may be advised for carriers. Female carriers can be identified by testing. The only way a woman could ever have hemophilia is if her father has it and her mother carries the gene. Women who are carriers can also be asymptomatic carriers, whereby they do experience factor deficiencies.

Generally, the first bleeding episode occurs before 18 months of age, often after a minor injury. A child who has hemophilia bruises easily. Even an injection into a muscle can cause bleeding that results in a large bruise (hematoma). Recurring bleeding into the joints and muscles can ultimately lead to crippling deformities. Bleeding can swell the base of the tongue until it blocks the airway, making breathing difficult. A slight bump on the head can trigger substantial bleeding in the skull, causing brain damage and death.

A doctor may suspect hemophilia in a child whose bleeding is unusual. A laboratory analysis of blood samples can determine whether the child’s clotting is abnormally slow. If it is, the doctor can confirm the diagnosis of hemophilia A and can determine the severity by testing the activity of factor VIII.