Inhibitors in young boys with haemophilia

The development of an inhibitor antibody to factor VIII (or factor IX) in a child with haemophilia presents a major challenge to the paediatric haemat ologist. This article provides an overview of the incidence of inhibitor de velopment in early childhood (30-52% in boys with severe haemophilia A), ge netic risk factors, detection, high titre, law titre and transient inhibito rs, and management. Treatment of patients with inhibitors is time-consuming and expensive. One should make every attempt to ensure that the boy's fami ly has an understanding of inhibitors, treatment options, and just what is being recommended for their child and what this involves. Immune tolerance induction is successful in similar to 85% of boys with factor VIII inhibito rs, but in only 40-50% of those with factor IX inhibitors. For treatment of bleeding episodes in children with high-titre (greater than or equal to 5 Bethesda Units) inhibitors, therapeutic options include activated prothromb in complex concentrates (APCC), rF VIIa, and (for factor VIII inhibitors) p orcine factor VIII. The advantages and disadvantages of each are discussed. Although factor IX inhibitors are far less common (occurring in 2-3% of bo ys with haemophilia B), approximately 50% are accompanied by the occurrence of anaphylaxis or severe allergic reactions to any factor IX-containing pr oduct.