The New England Journal of Medicine has published a study on the long-term efficacy of AAV8-mediated gene therapy (GNT0003) in patients with Crigler-Najjar syndrome, an extremely rare congenital liver disorder affecting approximately 500 people in Europe. It is caused by a deficiency of UGT1A1, an enzyme required for bilirubin metabolism. The accumulation of this substance can lead to irreversible neurological damage and, in the most severe cases, death.