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Condition report · Hematological

Congenital Factor XII Deficiency

An inherited lack of clotting factor XII that makes a common blood clotting test (aPTT) look prolonged but does not usually cause bleeding. It is caused by changes in the F12 gene, usually in both copies.

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The condition we analyse

Autosomal recessive

Caused by changes in both copies of F12 that reduce or abolish factor XII. Factor XII starts the contact pathway of clotting in laboratory tests but is not needed for normal blood clotting in the body. Different F12 changes are linked to a form of hereditary angioedema, which is a separate condition.

Signs and symptoms

Some people have no symptoms and are found when a clotting test shows a markedly prolonged activated partial thromboplastin time (aPTT). Bleeding is not usually increased. People with one altered copy have partly reduced levels.

What a diagnosis changes

No specific treatment is usually needed. Genetic counselling and carrier testing are available for relatives.

Genes analysed

Also known as

coagulation factor 12 deficiency; congenital Hageman factor deficiency; factor 12 deficiency; Factor XII Deficiency; Hageman Factor deficiency

MONDO:0009315OMIM 234000Orphanet 330MedGen 8772Sources: [2][4][3][5]

References

  1. F12 gene. MedlinePlus Genetics
  2. Chou SC, Lin CY, Lin HY, Pai CH, Yu CY, Kuo SF et al., 2022. Characterization of congenital factor XII deficiency in Taiwanese patients: identification of one novel and one common mutation. International journal of hematology
  3. Qu X, Jia Y, Wang Y, Xue F, Liu W, Chen Y et al., 2026. Clinical heterogeneity in congenital factor XII deficiency: Coexisting risk factors in thrombotic and bleeding events. British journal of haematology
  4. Weitz JI, 2017. Factor XI and factor XII as targets for new anticoagulants. Thrombosis research
  5. Sinnathamby ES, Issa PP, Roberts L, Norwood H, Malone K, Vemulapalli H et al., 2023. Hereditary Angioedema: Diagnosis, Clinical Implications, and Pathophysiology. Advances in therapy

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