Analyzes of liver biopsies from a child with spinal muscular atrophy revealed contaminating production plasmid sequences. Hepatitis developed in this patient treated with adeno-associated virus gene therapy. Disrupted vector genomes were also found in the liver. These findings are probably the result of recombination. The study was published in Nature Medicine online on January 16, 2026 with doi: 10.1038/s41591-025-04073-z.