Natural History Study of Factor IX Treatment and Complications
This study will examine two groups of subjects with factor IX (FIX) deficiency: 1) those with a current or history of inhibitors to FIX, and; 2) groups of two or more affected brothers, with or without inhibitors. The overall goal is to characterize the study groups in terms of their medical history, their patterns of bleeding, their care, quality of life, and complications including the development of joint disease, inhibitory antibodies to FIX, use of immune tolerance induction (ITI) and outcome.
• A consent approved by the appropriate Institutional Review Board (IRB)/Independent Ethics Committee (IEC) has been obtained from the subject or his legally acceptable representative
• Subject has FIX deficiency AND
‣ Is part of an affected brother pair/group that will also enroll; AND/OR
⁃ Has a current or history of inhibitor, defined as \>0.6 Bethesda units (BU)