Abstracts

Rationale:
Myoclonic epilepsy of Lafora or Lafora Disease (LD) is a fatal, autosomal recessive, glycogen storage disorder, and is a rare form of progressive myoclonus epilepsy (EPM2). LD typically starts in previously healthy adolescents, and symptoms rapidly evolve into progressive refractory epilepsy, cerebellar ataxia, and respiratory failure which lead to death within about a decade. Currently, there is no treatment available for LD. LD is caused by loss of function mutations in EPM2A or NHLRC1, which encode proteins laforin or malin respectively. Both laforin and malin are involved in regulating glycogen metabolism by an unclear mechanism. The absence of either protein results in aberrant cytoplasmic glycogen inclusions (Lafora bodies). Studies indicate that these intracellular inclusions are a principal driver of the disease pathology and, partial or full reduction of glycogen synthase in mouse models prevents LD. We hypothesized that targeting Gys1 with CRISPR-Cas9 will provide therapeutic benefit in LD mouse models by decreasing Lafora body formation. We tested this hypothesis as a proof of principle study, in two different LD mouse models.
Method:
We packaged Cas9 from Staphylococcus aureus (SaCas9) and a Gys1 targeting sgRNA in a recombinant adeno-associated virus (rAAV2/9). We injected neonatal mice with the rAAV-SaCas9 vectors via bilateral intracranial ventricular (ICV) injections. And, we aged mice to 3 months and harvested brain tissue for biochemical and histopathological analysis.
Results:
Our results show that disrupting Gys1 gene by CRISPR-Cas9 significantly decreases insoluble (abnormal) glycogen levels. Furthermore, rAAV-SaCas9 reduces Lafora body formation in the brain and prevents neuroinflammation.
Conclusion:
This study highlights the potential of in vivo CRISPR/Cas9 gene editing as an important path forward for the treatment of Lafora Disease.
Funding:
:The National Institute of Neurological Disorders and Stroke