Hemophilia is a rare genetic bleeding disorder in which a person
inherits problems with certain blood clotting factors, making
them unable to work properly. Blood-clotting factors are needed
to help stop bleeding after a cut or injury and to prevent
spontaneous bleeding. The hemophilia gene can contain many
different errors, leading to different degrees of abnormality in
the amount of clotting factor produced. People who have
hemophilia are at risk of abnormal bleeding throughout the body,
especially in the joints and muscles, which may lead to
disabling joint problems. Hemophilia occurs almost exclusively
in men. The disease can be passed from a mother who is a carrier
of the genetic defect (but who does not have the disease) to her
son. Rarely, a girl can have hemophilia. This occurs only if she
inherits a defective gene from both her mother and her father.
Symptoms of hemophilia are usually first noticed during infancy
or childhood. However, some people who have milder forms of
hemophilia may not develop s