Congenital deficiency of coagulation factor XII (Hageman factor) due to variants in the F12 gene. It is common in domestic cats and in several breeds and, in most cases, is asymptomatic without abnormal bleeding; it is detected in coagulation tests as a prolonged activated partial thromboplastin time (aPTT). Autosomal inheritance (recessive for very low residual activity). The test is complementary to the coagulation profile.

Common in domestic cats and present in several breeds; geographical bias towards the Midwest of the United States in the published series. Frequencies: limited data.

- Usually asymptomatic, without abnormal bleeding\n- Prolonged aPTT in coagulation tests\n- Low residual FXII activity (homozygotes) or moderate (heterozygotes)\n- No haemorrhagic signs in most cases

Maruyama et al. (2019) described that factor XII deficiency is common in domestic cats and is associated with two high-frequency mutations in the F12 gene: a missense mutation in exon 13 (c.1631G>C) and a deletion in exon 11 (c.1321delC); none of the 26 deficient cats had shown abnormal bleeding (PMID 31022435). Maruyama et al. (2017) described a missense mutation in exon 13 (p.Gly544Ala) in a litter with the deficiency (PMID 28392508).

- FXII deficiency does not usually cause abnormal bleeding: it is not in itself a reason to exclude from breeding\n- Interpret the result together with the coagulation profile (aPTT)\n- With an isolated aPTT prolongation, consider FXII deficiency before assuming a bleeding risk\n- Communicate the finding to the veterinarian to avoid unnecessary tests

Factor XII deficiency is a laboratory finding (prolonged aPTT) that in most cats has no haemorrhagic relevance; it must be differentiated from other coagulopathies (haemophilias, factor XI deficiency, von Willebrand disease). Complementary: measurement of FXII activity and coagulation profile.

1. Maruyama H et al. 2019, la deficiencia de factor XII es común en gatos domésticos y se asocia a dos mutaciones de alta frecuencia de F12 (PMID 31022435)
2. Maruyama H et al. 2017, nueva mutación missense de F12 en una camada de gatos con deficiencia de factor XII (PMID 28392508)