A 25-year-old Ashkenazi Jewish woman presents with prolonged bleeding after dental extraction. aPTT is prolonged, PT is normal, platelet count and bleeding time are normal. Which factor deficiency is most likely?

• A Factor VIII
• B Factor IX
• C Factor XII
• D Factor XI ✓

Explanation

Factor XI deficiency is particularly common in Ashkenazi Jews (carrier frequency up to 8-9%). It causes a prolonged aPTT with normal PT and bleeding time. Unlike hemophilia A and B, bleeding tendency correlates poorly with factor level, and thrombosis can occur after replacement therapy. Factor XII deficiency prolongs aPTT but does not cause bleeding.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.