Hemophilia is an inherited blood clotting disorder, occurring primarily in males, in which one or more of the 15 vital clotting proteins, called clotting factors, are either deficient or inactive.
If you will, imagine a set of dominos lined up on end, in a row, placed a little less than one domino length apart. Normally, if you pushed the first domino, you would have a cascade effect. However, if a domino is missing the sequence will be interrupted and some of the dominos will be left standing. The same is true of the clotting process. If one of the elements in the clotting process is missing or inactive, the next clotting factor in the sequence will not be triggered and the clotting process will stop.
Many believe that an individual with hemophilia will bleed harder or faster than normal, or that they can bleed to death from a small cut. THIS IS NOT TRUE! However, individuals with hemophilia, because of their inability to form a blood clot, will bleed longer. Small surface cuts and bruises are usually not a problem and normally clot on their own. Internal bleeding into a muscle, joint, organ, or head is more serious and typically requires treatment. Head injuries resulting in brain hemorrhage can also be life threatening.
Hemophilia A, also known as Classical Hemophilia or Factor VIII Deficiency, is the most common form of Hemophilia, comprising of about 80% of all individuals with Hemophilia. Hemophilia A is caused by a deficiency of a clotting protein called factor VIII.
Hemophilia B, also known as Christmas Disease or Factor IX Deficiency, is the second most common form of Hemophilia affecting the majority of the remaining 20% individuals with Hemophilia. Hemophilia B is caused by a deficiency of a clotting protein called factor IX.
Other Types of Hemophilia or even multiple clotting factor deficiencies do exist and are rare.
There are also other bleeding disorders that may produce symptoms similar to Hemophilia. Probably the most common inherited bleeding disorder, estimated to affect up to three percent of the population, is von Willebrand Disease, which is caused by a deficiency of a blood protein by the same name.