Summary
A bioRxiv preprint reports that neonatal AAV-SIL1 gene therapy prevented neurological and muscle disease in a mouse model of Marinesco-Sjögren syndrome. The treatment preserved cerebellar Purkinje cells and maintained its effects through 26 weeks.
A bioRxiv preprint reports that a neonatal gene-therapy treatment prevented the main neurological and muscle features of Marinesco-Sjögren syndrome in mice. The study used an adeno-associated virus (AAV) to deliver a working copy of SIL1, the gene affected by loss-of-function mutations in the rare early-onset disorder.
Marinesco-Sjögren syndrome is a multisystem disease characterised primarily by cerebellar ataxia—impaired coordination caused by dysfunction in the cerebellum—and myopathy, or muscle disease. The source states that no disease-modifying therapy is currently available.
What the mouse study tested
The researchers used the woozy mouse, a model of Marinesco-Sjögren syndrome. Neonatal mice received an intracerebroventricular injection, meaning the treatment was delivered into the brain’s ventricular system. The vectors were based on AAV-PHP.eB and carried the SIL1 gene.
The study tested vectors in which SIL1 expression was controlled either by a ubiquitous promoter, intended to work broadly across cells, or by a promoter specific to cerebellar Purkinje cells. Purkinje cells are neurons in the cerebellum that are central to coordinating movement.
Vehicle-treated woozy mice developed motor impairment, degeneration of Purkinje cells and activation of endoplasmic-reticulum stress pathways. These pathways are cellular responses associated with problems processing or folding proteins.
Neurological and muscle outcomes
The AAV-SIL1 treatment prevented the onset of ataxia and preserved Purkinje cells. It also reduced activation of the stress pathways seen in untreated disease-model mice.
The Purkinje-cell-specific experiment provided a more focused result. Selectively restoring SIL1 expression in Purkinje cells was sufficient to rescue motor performance in the mice. The researchers interpret this as evidence that dysfunction within Purkinje cells themselves makes a cell-autonomous contribution to the motor problems associated with the syndrome.
The benefit was maintained throughout the study’s 26-week observation period. The treated mice also showed improved muscle function and less severe muscle pathology, indicating that the intervention affected both major disease manifestations examined in the model rather than motor coordination alone.
Why the result matters
The findings provide preclinical proof-of-principle for replacing or restoring SIL1 through AAV gene therapy. They also connect a specific cerebellar cell population to the disease’s motor phenotype and suggest that correcting SIL1 in Purkinje cells may be an important part of a therapeutic strategy.
The result is especially relevant because the treatment addressed the genetic defect at an early stage and produced effects across neurological and muscular outcomes. The authors say the findings support development of gene-therapy approaches that could ultimately be adapted for Marinesco-Sjögren syndrome.
This remains an early-stage, preventive study in mice. It is a bioRxiv preprint, and the supplied abstract does not state the number of animals in each group. The experiment used neonatal administration and followed the animals for 26 weeks, so whether the approach can be safely and effectively adapted to people—or used after disease symptoms have begun—requires further research.