Juvenile neuronal ceroid lipofuscinosis (JNCL), also called CLN3 Batten Disease, is a debilitating autosomal recessive neurodegenerative disorder affecting children with onset around 4-10 years of age. The lack of functional CLN3 protein causes accumulation of cellular waste (storage material) due to malfunction of the lysosomes, as well as other intracellular defects including mitochondrial dysfunction. Affected children display rapid vision loss in most cases, followed by decline in motor function, behavior and cognition accompanied by development of seizures. While a few treatments are currently advancing through various stages of clinical trials, there is no cure or effective treatment for CLN3 Batten Disease that could change the course of this degenerative disorder. Thus, current treatment focuses on symptom management. Natural history studies indicate worsening of individuals by about 2.86 - 3.02 points/year on the physical impairment subscale of the Unified Batten Disease Rating Scale (UBDRS). CLN-301 is an AAV9 gene replacement therapy that was developed by Investigators at Nationwide Children’s Hospital, Columbus, Ohio. To date, 4 patients were treated with this gene therapy via lumbar intrathecal injection in the ongoing phase I/II clinical trial. Data from 3- and 5-year follow-up indicate a statistically significant and meaningful slowing of disease progression (mean on UBDRS physical impairment score at 3 years post treatment -0.13 points). Cognitive, speech and motor function were also evaluated in 2 patients in a long-term follow up to 5 years post injection showing remarkable stability and  maintenance of cognitive, speech and motor function. Together, the data underlines the high potential of CLN-301 for treatment of CLN3 Batten Disease patients supporting further development and continuation of clinical testing.