Hemophilia
What Is Hemophilia?
Hemophilia is a disease that prevents a person's blood from clotting properly, which means that the person bleeds more than a person without hemophilia does. It's a genetic disorder, which means it's the result of a change in genes that's either inherited (passed on from parent to child) or that happens during development in the womb. "Hemo" means blood and "philia" means a tendency toward. A person who has hemophilia has a tendency to bleed excessively. Hemophilia affects mostly boys, although it's very rare: Only about one in every 8,000 boys is born with hemophilia. The disease can affect people of any race or nationality.
For most people, when they get a cut, the body naturally protects itself. Sticky cells in the blood called platelets go to where the bleeding is and plug up the hole. This is the first step in the clotting process. When the platelets plug the hole, they release chemicals that attract more sticky platelets and also activate various proteins in the blood known as clotting factors. These proteins mix with the platelets to form fibers, and these fibers make the clot stronger and stop the bleeding.
Our bodies have 12 clotting factors that work together in this process (numbered using Roman numerals from I through XII). Having too little of factors VIII (8) and IX (9) is what causes hemophilia. A person with hemophilia will only lack one factor, either factor VIII or factor IX, but not both.
There are two major kinds of hemophilia. About 80% of cases are hemophilia A, which is a factor VIII deficiency. Hemophilia B is when factor IX is lacking.
Hemophilia is classified as mild, moderate, or severe, based on the amount of the clotting factor in the person's blood. If someone produces only 1% or less of the affected factor, the case is called severe. Someone that produces 2% to 5% has a moderate case, and someone that produces 6% to 50% of the affected factor level is considered to have a mild case of hemophilia. In general, a person with milder hemophilia may only bleed excessively once in a while, whereas severe hemophilia puts someone at risk for having bleeding problems much more often.
Most people with hemophilia discover they have the condition when they are babies or young kids. Sometimes the disease is so mild that a guy doesn't even know he has it until he has minor surgery - like getting his tonsils or appendix out - and it's found in blood tests that doctors perform before surgery.
What Causes Hemophilia?
Men and women each have 23 pairs of chromosomes (pronounced: kro-muh-soamz). Women have two X chromosomes; men have one X and one Y chromosome. Hemophilia is an X-linked genetic disorder, which means that it's passed from mother to son on the X chromosome. If the mother carries the gene for hemophilia on one of her X chromosomes, each of her sons will have a 50% chance of having hemophilia. Although girls rarely develop the symptoms of hemophilia itself, they can be carriers of the disease. For a girl to get hemophilia, she would have to receive the disease on the chromosome she receives from her father, who would have hemophilia, as well as from the X chromosome of her mother, who would be a carrier. Although this is not impossible, it is highly unlikely.
What Are the Signs and Symptoms?
If you've just found out you have hemophilia, you probably have a milder form of the disease. Symptoms of hemophilia include:
- Bruises that are unusual in location or number
- Nosebleeds that won't stop
- Excessive bleeding from biting a lip or having a tooth pulled
- Painful or swollen joints
- Blood in the urine
Credit: National Institute of Health.