In vivo base editing of Chd3 rescues behavioural abnormalities in mice.

Neurodevelopmental disorders that arise from de novo mutations in chromatin-remodelling genes lack targeted treatments. Snijders Blok-Campeau syndrome (SNIBCPS)(1), which is caused by pathogenic variants in CHD3, manifests with intellectual disability, autistic-like behaviours and motor deficits(2). Whether somatic gene correction can reverse such phenotypes in vivo remains unknown. Here we show that modelling the recurrent CHD3 variant p.R1025W in a humanized mouse model (Chd3(hR1025W/+)) recapitulates key features of SNIBCPS, including reduced CHD3 protein levels and abnormalities in social communication, cognition and motor coordination. We engineered a TadA-embedded adenine base editor (TeABE) and delivered it brain-wide using a dual adeno-associated virus (AAV) system and achieved efficient on-target A•T-to-G•C correction across multiple cortical and hippocampal regions with minimal bystander activity. This intervention restored CHD3 levels and ameliorated behavioural abnormalities in vivo. Furthermore, intrathecal dual AAV delivery in nonhuman primates resulted in widespread neuronal transduction and efficient TeABE reconstitution, a result that supports its translational feasibility. These findings establish in vivo base editing as a viable therapeutic approach for CHD3-related neurodevelopmental disease. More broadly, they demonstrate that precise single-base correction in the postnatal brain can restore protein dosage and function, thereby offering a framework for the treatment of monogenic neurodevelopmental disorders.