Successful induction of immune tolerance with FIX recombinant in a patient with haemophilia B with inhibitor.

We describe successful induction of immune tolerance in a 12-month-old patient with severe haemophilia B and low-titre and low response antifactor IX inhibitor at 5 Bethesda Unit (BU). Immune tolerance induction (ITI) was started with recombinant factor (rFIX) at 40-50 U kg(-1) day(-1) (1000 U three times per week) and 2 years after the beginning of therapy the inhibitor had been reduced to undetectable values. As complications, which appeared during the ITI, the patient presented minor haemorrhagic complications, which remitted following the administration of rFVIIa, and recurring infections of the catheter, requiring the withdrawal and subsequent placement of a new catheter.