This deficiency is an inherited condition that affects a protein known as the factor XII that is required for the process of blood clotting after a bleeding episode. As the blood in the body is transported in a network of various blood vessels, when damage to any of this part occurs, blood leaks through the holes that develop. The coagulation is a complex process that stops the damaged blood vessels from leaking. When the blood vessel wall breaks, the materials required for the coagulation process come together to form a plug that stops the leakage. Deficiency in the XII factor does not require any treatment as this usually does not cause any abnormal bleeding. The severe form of this condition is extremely rare and is estimated to affect around 1 in 1 million individuals.
Causes
This condition is inherited in an autosomal recessive manner meaning both the copies of the gene from the parents are defective. When an individual inherits one abnormal gene and one normal gene, they will normally be the carrier of the disease without exhibiting any symptoms. However, the risk of having a child with the disease increases by 25% when two carrier parents pass the defective gene. The gene identified to cause factor XII deficiency is F12 which is essential for the production of factor XII. The genetic mutation results in less quantity of functional factor XII which causes the XII factor deficiency. The factor XII, in addition, may also be required for the tissue repair and the development of the blood vessels.
Symptoms
This condition generally does not present any symptoms. The blood level of factor XII appears to differ greatly among the cases and various tests done to measure the clotting time indicates long time for blood to clot. Medical reports suggest that the individuals with this condition may be at risk of developing blood clots known as thrombosis in their bloodstream at an early age.
Diagnosis
Factor XII deficiency is usually diagnosed accidentally before a surgery as a routine blood clotting tests. The diagnosis is based on tests such as the activated partial thromboplastin time (aPTT) or prothrombin time (PT) which measures the duration it is required for the blood to clot. An additional test to confirm the diagnosis includes an assay that evaluates the coagulation factors which is an indication of factor VII deficiency.
Treatment
Unlike the other forms of coagulation disorders, this deficiency does not result in any excessive bleeding and the treatment is generally considered unnecessary. However, as this condition may present mild bleeding abnormality, it is important to notify the dentist and the physicians to prevent any delays with the surgical procedure.
References
http://www.hemophilia.ca/en/bleeding-disorders/other-factor-deficiencies/factor-xii-deficiency/
https://rarediseases.org/rare-diseases/factor-xii-deficiency/
