Viral gene therapy for paediatric neurological diseases: progress to clinical reality

In the era of genomic medicine, diagnoses of rare paediatric neurological diseases are increasing. Many are untreatable and life-limiting, leading to an exceptional increase in gene therapy development. It is estimated that 20 gene therapy products will have received approval from the US Food and Drug Administration by 2025. With viral gene therapy considered a potential single-dose cure for patients with spinal muscular atrophy type 1 as one example, and contemporaneously tragically resulting in the deaths of three male children with X-linked myotubular myopathy receiving high-dose gene therapy in 2020, what is the current state of gene therapy? What is behind the decades of hype around viral gene therapy and is it high impact, but high risk? In this review, we outline principles of viral gene therapy development and summarize the most recent clinical evidence for the therapeutic effect of gene therapy in paediatric neurological diseases. We discuss adeno-associated virus and lentiviral vectors, antisense oligonucleotides, emerging genetic editing approaches, and current limitations that the field still faces. What this paper adds Viral gene therapy development and clinically used transgenes, regulatory elements, capsids, dosage, and delivery routes are summarized. Viral gene therapy for 18 childhood neurological disorders involving over 600 children in 40 clinical trials are reviewed.