Which statement best describes the clinical significance of isolated Factor XII deficiency?

Which statement best describes the clinical significance of isolated Factor XII deficiency?

• A. Negative bleeding history
• B. Prolonged PFA
• C. Decreased risk of thrombosis
• D. Epistaxis

Answer: (A)

Factor XII (Hageman factor) is part of the intrinsic contact activation pathway, and its deficiency prolongs the aPTT in lab testing but does not impair actual hemostasis in vivo. Because FXII is not essential for normal clot formation to stop bleeding, isolated FXII deficiency typically produces no bleeding symptoms. That’s why a negative bleeding history best describes its clinical significance. Prolonged PFA is not a characteristic finding of FXII deficiency, epistaxis would indicate a bleeding tendency, and whether there is any decreased risk of thrombosis is not reliably established for isolated FXII deficiency.

Factor XII (Hageman factor) is part of the intrinsic contact activation pathway, and its deficiency prolongs the aPTT in lab testing but does not impair actual hemostasis in vivo. Because FXII is not essential for normal clot formation to stop bleeding, isolated FXII deficiency typically produces no bleeding symptoms. That’s why a negative bleeding history best describes its clinical significance. Prolonged PFA is not a characteristic finding of FXII deficiency, epistaxis would indicate a bleeding tendency, and whether there is any decreased risk of thrombosis is not reliably established for isolated FXII deficiency.