Hemophilia is a rare disorder in which the blood does not clot normally due to a lack of clotting protein known as factor. Hemophilia causes excessive bleeding that can occur inside the body, typically into the joints or muscles, or externally from a cut or other injury.  

Symptoms of hemophilia

According to the National Heart, Lung, and Blood Institute, symptoms include:

  • Excessive Bleeding – This may be external or internal bleeding.
    • External bleeding may consist of nosebleeds, bleeding in the mouth, heavy bleeding from a minor cut, and bleeding from a cut that resumes after a brief stop.
    • Internal bleeding may consist of large bruises and blood in the urine or stool.
  • Bleeding in the Joints – Bleeding in the knees, elbows, or other joints, without obvious injury, may cause tightness with no real pain or visible signs of bleeding. The joint becomes swollen, hot to the touch, and painful to bend. Eventually, movement in the joint is temporarily lost and pain can be severe.
  • Bleeding in the Brain Symptoms include headaches and neck pain; vomiting; changes in behavior, balance, and dexterity; double vision; and seizures.  

Types of hemophilia

There are two main types of inherited hemophilia: A and B.

  • Hemophilia A, also known as Classic hemophilia or Factor VIII deficiency, has missing or low levels of clotting factor VIII. According to the National Heart, Lung, and Blood Institute, 80% of people with hemophilia have Type A.  
  • Hemophilia B, also known as Christmas disease or Factor IX deficiency, has missing or low levels of clotting factor IX.

How is hemophilia inherited?

Hemophilia is caused by a mutation in one of the genes that determines how the body makes blood clotting factor VIII or IX. These gene abnormalities are typically carried by females and expressed in males.  A woman who carries the abnormal gene has a 50% chance of transmitting the disease to her unborn male children.    

Although the condition is usually hereditary, a spontaneous gene mutation may also cause hemophilia.

How is hemophilia diagnosed?

Blood tests may be performed to find how long it takes blood to clot, whether the blood has low levels of any clotting factors, or whether any clotting factors are completely missing from the blood.  The amount of clotting factors in the blood determines if one has mild, moderate, or severe hemophilia.  The fewer the clotting factors, the more severe the disorder.  Depending on the severity of the disorder, symptoms of hemophilia can vary but often include bruising or prolonged bleeding that happens often or easily.