Proteins and other chemicals in the blood exist in a fine balance between clotting too easily, resulting in plugged blood vessels, and not clotting enough, resulting in the tendency to bleed. Disorders caused by forming blood clots too easily are called thrombophilias or hypercoagulable states. They may be inherited or acquired.
Activated Protein C Mutation
Activated protein C deficiency, also known as factor V Leiden mutation, is the most common form of inherited tendencies to form blood clots. According to the National Institutes of Health, the mutation is most common in Caucasian populations, with about 5 percent of the population having one copy of the gene, exposing them to about six times the risk of forming blood clots in the veins. About 1 in 5,000 people has two copies, exposing them to up to 80 times the risk of forming blood clots. There is also an increased risk of complications during pregnancy.
Prothrombin Mutation
The prothrombin mutation, or more specifically prothrombin G20210A mutation, is the second most common inherited hypercoagulable state. According to the University of Illinois-Urbana/Champaign Carle Cancer Center, this mutation is also more common in the Caucasian population, with about 1 to 2 percent of the population having the one copy of the gene. The risk of developing a clot in the deep veins is about 1 in 1,000 with the mutation.
Homocysteinemia
The chemical homocysteine is normally found in the blood. Mutations in one of two different enzymes can raise the levels of homocysteine, which carries an increased risk of blood clots, particularly in the presence of other risk factors, such as smoking. The mutation is quite common at perhaps 20 percent of the population. However, most people with the mutation do not get blood clots. It is the only one of the three most common inherited conditions that is directly treatable. The others may be treated with medications that interfere with multiple steps leading to the formation of blood clots. Homocysteinemia may be treated with vitamin supplementation under the supervision of a health-care professional.
Others
The above are three of the most common inherited tendencies to blood clotting. Some of the others include protein C deficiency and protein S deficiency, antithrombin III deficiencies in which the levels or functions of these proteins are compromised. Normally, they function to help inhibit clotting or break down blood clots. In the condition dysfibinogenemia, the fibrous strands of blood clots are resistant to the enzymes responsible for breaking them down. Two other types with similar mechanisms of dysfunction include plasminogen deficiency and heparin cofactor II deficiency.
