[Effective gene therapy for hemophilia, at last…].

Recent efforts at gene therapy for haemophilia A and B using AAV-derived vectors show durable expression of coagulation factors at significant levels, resulting in almost complete correction of the phenotype. This is the first success of gene therapy for a major hereditary disorder, and shows how continuous improvement of many components of the system has finally succeeded. Although these results must be confirmed with more patients and longer durations, they constitute a significant accomplishment for this approach after decades of frustration.