Some Basic Facts About Hemophilia
Blood contains at least ten proteins (called clotting factors) that must work together in order for blood to clot properly. These clotting proteins are numbered I - XIII. When a person's blood is not able to clot, the person has a bleeding disorder. The best-known bleeding disorder is hemophilia. More than 15,000 people in the US have hemophilia (either hemophilia A or hemophilia B). Hemophilia is caused by a defect in or lack of clotting factor VIII is called hemophilia A (sometimes known as classic hemophilia). Hemophilia caused by a defect in or lack of clotting factor IX is called hemophilia B (sometimes known as Christmas disease, named for the first person that was known to have this disorder). People cannot catch hemophilia; they are born with it. Hemophilia is a hereditary disease, in other words, it runs in families (is inherited). Clotting factor defects are genetic. Genes determine everything physical about a person such as eye color, hair color and function of clotting factors. Before a baby is born, it receives half of its genetic information from its mother (through her egg cell) and half from its father (through his sperm cell). If the mother or father has the hemophilia gene, it may be passed to the baby through the egg or sperm. If a man with hemophilia fathers a child, his sons will not have hemophilia, but his daughters will all be carriers. If a man fathers a child and his female partner is a carrier, the baby could have hemophilia, even if it is a girl. This is extremely rare. Complications of bleeding disorders include HIV infection, hepatitis and joint problems. Some children born with hemophilia have no family history of the disease. Genetic changes can occur for no reason. Doctors believe that 30% of all children born with hemophilia have no family history of the disease. Although these cases occur spontaneously, they can pass the hemophilia gene on to their children. Until 1965, the only available treatment for hemophilia, other than rest and using ice, was whole blood or fresh frozen plasma transfusions that could only be given in hospitals. Since the late 1970s, much progress has been made in the treatment of hemophilia. Examples of these improvements include the availability of new clotting factor products and drugs such as desmopressin acetate (DDAVP), new synthetic clotting products that take advantage of recombinant technologies, better screening methods to detect and remove viruses and other agents from factor concentrates, improved surgical options, advanced genetic testing methods, medically supervised home-infusion therapy and prophylactic treatment. Management of bleeding disorders places a large financial burden on affected individuals and their families. In fact, clotting factor products are among the most costly treatments in the world, and the annual costs may exceed $100,000 per individual. Complications such as major surgery or HIV can cause costs to skyrocket even further. Access to the newest, safest and most effective treatment options depends upon adequate health insurance. Often, insurance policies have limits called "caps" on certain services or treatments, which can limit access to helpful therapies. Researchers are working to develop cures for bleeding disorders. One promising approach relies on a process called gene therapy. The idea behind gene therapy is to insert a healthy version of the defective blood factor gene into persons with bleeding disorders. It is assumed that this will change their genetic make-up and permit them to produce normal amounts of factor on their own. While simple in theory, gene therapy research is proving more complex in practice. Below is a table that provides very basic information about every known inherited bleeding disorder, plus some other information, originally published in the American Journal of Medicine:Inherited Bleeding Disorders
Just as deficiency of certain players in the coagulation cascade leads to a thrombotic tendency, deficiencies in other coagulation factors leads toward a tendency to bleed. In the normal physiologic state, factors XIa, VIIa, IXa Va, Xa, VIIa, and thrombin are procoagulants. Antithrombin III, Proteins C & S, thrombomodulin, and plasmin function as anticoagulants. Deficiencies in any of the procoagulants can lead to a state where there is a propensity to bleed. The table below summarizes the major inherited bleeding disorders.| Coag. Protein Deficiency | Inheritance Pattern | Prevalence |
| Factor I (fibrinogen) Afibrinogenemia Hypofibrinogenemia Dysfibrinogenemia |
Autosomal recessive Autosomal dominant or recessive Autosomal dominant or recessive |
Rare (<300 families) Extremely rare Rare (>200 types) |
| Factor II (prothrombin) | Autosomal dominant or recessive | Extremely rare< |
| Factor V Leiden | Autosomal recessive | 1 in 1 million births |
| Factor VII | Autosomal recessive | 1 in 500,000 births |
| Factor VIII (hemophilia A) Factor VIII inhibitor |
X-linked recessive Acquired |
1 in 5,000 male births (no data) |
| Factor IX (hemophilia B) | X-linked recessive | 1 in 30,000 male births |
| Factor X | Autosomal recessive | 1 in 500,000 births |
| Factor XI | Autosomal dominant | 4% of Askenazi Jews, otherwise rare |
| Factor XIII | Autosomal recessive | 1 in several million births |