A bleeding disorder exists when it is hard for a person to stop bleeding. When a person bleeds, the blood clots, stopping the bleeding. The clotting process, also called coagulation, changes blood from a liquid to a solid state. It takes both blood cells (called platelets) and proteins (called clotting factors) for blood to clot properly. When a person has a bleeding disorder, the blood platelets are not working like they should, or there are not enough platelets or clotting factors in the blood. This causes a person to bleed for longer periods of time than normal. Normal blood coagulation is a complex process involving as many as 20 different plasma proteins, which are known as blood clotting or coagulation factors. Normally, these factors interact with other chemicals to form a substance called fibrin that stops bleeding. When certain coagulation factors are deficient or missing, the process is impaired. Bleeding problems can range from mild to severe.
Some bleeding disorders are present at birth and are caused by rare inherited disorders. Others are developed during certain illnesses (such as Vitamin K deficiency or severe liver disease), or treatments (such as use of anticoagulant drugs or prolonged use of antibiotics). These disorders can be either inherited or acquired. The acquired forms often arise from the side effects of certain drugs. These disorders can be controlled, so a person can have a healthy and full life.
Hemophilia is an inherited bleeding disorder, predominantly affecting males. There are two major forms of the disease - hemophilia A (factor VIII deficiency) and hemophilia B (factor IX deficiency). People with no family history can also develop hemophilia A. NHF says this accounts for a third of all cases. It usually happens after a new or spontaneous gene mutation.
Hemophilia may result from gene mutations: point mutations involving a single nucleotide, deletions of all or parts of the gene, and mutations affecting gene regulation. About 50% of cases of severe hemophilia A result from a major inversion of a section of the tip of the long arm of the X chromosome. Because factor VIII and factor IX genes are located on the X chromosome, hemophilia affects males almost exclusively. Daughters of hemophiliacs will be obligatory carriers, but sons will be normal. Each son of a carrier has a 50% chance of being a hemophiliac, and each daughter has a 50% chance of being a carrier. Rarely, random inactivation of one of the two X chromosomes in early embryonic life will result in a carrier's having a low enough factor VIII or IX level to experience abnormal bleeding.
von Willebrand Disease is a hereditary deficiency of von Willebrand factor in blood, occurring in 1% to 2% of the population. The factor is a protein that affects platelet function. von Willebrand disease was first recognized in 1925 by Erik von Willebrand, a Finnish physician, who described a new type of bleeding disorder in inhabitants of the Aland Islands.
According to NHF there are many variations of von Willebrand disease including:
Links to other bleeding disorders information: