Deficiency of coagulation factor XII (Factor XII deficiency) - Gen F12.

Factor XII deficiency is a hereditary disorder characterized by a deficiency of Factor XII in the blood. Generally, people with this disorder do not have abnormal bleeding or other symptoms. This alteration can be detected in people affected in a routine blood test, because the reduction of concentrations of factor XII cause blood to clot more later in a test tube. Some affected individuals may have a tendency to hemorrhage, cerebral stroke, local edema, severe headache, abdominal pain, various forms of allergy, thrombophlebitis and ulcer.

This process is due to mutations in the F12 gene, located on the long arm of chromosome 5 (5q35.3). This gene encodes a protein called Factor XII. Coagulation factors are a group of related proteins that are essential for normal blood clotting. After injury, clots protect the body by sealing damaged blood vessels to prevent further blood loss. The factor XII circulates in the bloodstream in an inactive form until activated, usually by contact with the walls of damaged blood vessels. Upon activation, the factor XII interacts with coagulation factor XI. This interaction triggers a series of additional chemical reactions that form a blood clot. XII factor also plays a role in stimulating inflammation, a normal response of the body to infection, irritation, or other injuries. When activated factor XII, also it interacts with a protein called plasma prekallikrein. This interaction initiates a series of chemical reactions that result in the release of a protein called bradykinin. Bradykinin promotes inflammation by increasing the permeability of the walls of blood vessels, allowing fluids filtrenmás in body tissues. This leakage causes inflammation.

They have identified approximately 20 mutations in the F12 gene, leading to deficiency of factor XII. Most mutations in the amino acid replaced Factor XII, altering the structure of factor XII. It is unclear why people deficient in factor XII have no abnormal bleeding as those with deficiencies in other clotting factors.

Factor XII deficiency is inherited as an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with Factor XII deficiency, by complete PCR amplification of exons gene F12, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).