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Factor XII Deficiency (Variant 1)

Factor XII Deficiency, also known as Hageman trait, is an asymptomatic blood factor deficiency. While it does not cause an abnormal tendency to bleed, it can be observed as prolonged blood clotting times during certain laboratory screening tests.

Key Signs

Asymptomatic, Clinically prolonged blood clotting times

Age of Onset

At birth

Present at birth


Autosomal Recessive - Asymptomatic

For autosomal recessive, asymptomatic disorders, cats with two copies of the variant will show the variant-associated condition but will not suffer disease due to this genetic cause. Cats with one copy of the variant are called carriers, and although they will not display signs of the condition, they may pass the variant on to their kittens if bred.

Likelihood of the Condition

High likelihood

Cats with two copies of the variant are highly likely to show the variant-associated condition but will not suffer disease due to this genetic cause.

What to Do

Here’s how to care for a cat with Factor XII Deficiency

Partner with your veterinarian to make a plan regarding your cat’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about Factor XII Deficiency

Blood coagulation is a complex process involving many pathways. Factor XII, a plasma protein, classically initiates the intrinsic pathway of blood coagulation; although, there are alternative, slower ways to initiate this pathway. Factor XII Deficiency, also known as Hageman Factor Deficiency or Hageman trait, is a commonly inherited blood clotting disorder in cats. Unlike other bleeding disorders, cats deficient in Factor XII are asymptomatic and do not tend to show spontaneous bleeding or abnormal bleeding after surgery or trauma. However, affected individuals can have prolonged clotting time on the activated partial thromboplastin time (aPTT) screening test. Cats who inherit 2 copies of both Factor XII Deficiency (Variant 1) and Factor XII Deficiency (Variant 2) may show even higher aPTT values. Please note that 1 copy of Factor XII Deficiency (Variant 1) and 1 copy of Factor XII Deficiency (Variant 2) will not cause Factor XII Deficiency.

In most cases, Factor XII Deficiency is considered an incidental clinical finding. Unless inherited in conjunction with another disease process, no further steps are necessary as affected cats do not typically show clinical bleeding problems.

For Breeders

Planning to breed a cat with this genetic variant?

There are many responsibilities to consider when breeding cats. Regardless of test results it is important that your cat is in good general health and that you are in a position to care for the kittens if new responsible owners are not found. For first time or novice breeders, advice can be found at most cat registry websites.

This condition is autosomal recessive, asymptomatic, meaning that cats with two copies of the variant will show the variant-associated condition but will not suffer disease due to this genetic cause. Current understanding is that a cat with one or two copies of the Factor XII Deficiency variant can be safely bred with a cat with zero, one or two copies of the variant. Please note: It is possible that clinical signs similar to the ones caused by the Factor XII Deficiency mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene F12
Variant Deletion
Chromosome A1
Coordinate Start 175,381,114
Coordinate End 175,381,113

All coordinates reference FelCat9.0

References & Credit

Credit to our scientific colleagues:

Bender, D. E., Kloos, M. T., Pontius, J. U., Hinsdale, M. E., & Bellinger, D. A. (2015). Molecular Characterization of Cat Factor XII Gene and Identification of a Mutation Causing Factor XII Deficiency in a Domestic Shorthair Cat Colony. Veterinary Pathology, 52(2), 312–320. View the article

Maruyama, H., Brooks, M. B., Stablein, A., & Frye, A. (2019). Factor XII deficiency is common in domestic cats and associated with two high frequency F12 mutations. Gene, 706, 6–12. View the article