Study to Describe the Allergic Reactions to Factor IX in Patients With Hemophilia B

You may be eligible if

• Written consent to release patient information
• Living or deceased patients with mild to severe hemophilia B who have had at least 1 exposure to replacement factor IX product(s).
• Living or deceased patients who had their first infusion of any FIX product between 1 January 1991 and 31 December 2003.