Neuronal ceroid lipofuscinosis, commonly known as Batten disease, is an inherited pediatric neurodegenerative lysosomal storage disease caused by mutations in the CLN5 gene. The disease is incurable and there is an urgent medical need for novel therapies. A murine model of Batten disease was developed to study a novel AAV vector that expresses CLN5, AAV9-CLN5. In the study by University College London investigators, the gene therapy, driven by the synapsin promoter, was intracerebroventricularly administered into neonatal Cln5-knockout mice.