Factor XII Deficiency and Infections?

From “Sunny:”
Do people with factor XII (Hageman factor) deficiency suffer constant infection? Can you provide references?

Hello and thank you for your question. No, there is no clinical relationship between coagulation factor XII deficiency and infections. Factor XII deficiency is relatively common; one study* reported a prevalence of 2% among normal subjects. Although factor XII deficiency markedly prolongs the partial thromboplastin time (PTT), no clear physiologic role has been described for the factor; it is not associated with bleeding. Several published anecdotes propose a relationship with thrombotic risk, however many of these could be explained by the presence of lupus anticoagulant, which prolongs the PTT, producing the artifactual appearance of factor XII deficiency. Through its relationship with prekallikrein and high molecular weight kininogen, factor XII may potentially interact with inflammatory and complement systems, however, as with coagulation, there appears to be no clear physiologic effect of factor XII deficiency upon inflammation. I hope this is helpful.

*Halbmayer WM, Haushofer A, Schon R, et al. The prevalence of moderate and severe factor XII (Hageman factor) deficiency among the normal population: evaluation of the incidence of factor XII deficiency among 300 healthy blood donors. Thromb Haemost 71: 68–72, 1994.