Sper, R. | bioRxiv Science

bioRxiv2025

A preclinical pig model of Angelman syndrome mirrors the early developmental trajectory of the human condition

Angelman syndrome is a neurodevelopmental disorder characterized by severe motor and cognitive deficits. It is caused by the loss of the maternally inherited allele of the imprinted ubiquitin-protein ligase E3A (UBE3A) gene. Rodent models of Angelman syndrome do not fully recapitulate all the symptoms associated with the condition and are limited as a preclinical model for therapeutic development. Here, we show that pigs (Sus scrofa) with a maternally inherited deletion of UBE3A (UBE3A-/+) have altered postnatal behaviors, impaired vocalizations, reduced brain growth, motor incoordination, and ataxia. Neonatal UBE3A-/+ pigs exhibited several symptoms observed in infants with Angelman syndrome, including hypotonia, suckling deficits, and failure to thrive. Collectively, these findings are consistent with the pathophysiology and developmental trajectory observed in individuals with Angelman syndrome. We anticipate that this pig model will advance our understanding of the pathophysiology of Angelman syndrome and be used as a preclinical large animal model for therapeutic development.

genetics↗

bioRxiv2025

Single-AAV CRISPR editing of skeletal muscle in non-human primates with NanoCas, an ultracompact nuclease

CRISPR gene editing is a transformative technology for addressing genetic diseases, but delivery constraints have largely limited its therapeutic applications to liver-targeted and ex vivo therapies. Here, we present the discovery and engineering of NanoCas, an ultracompact CRISPR nuclease capable of extending CRISPRs reach in vivo beyond liver targets. We experimentally screened 176 ultracompact CRISPR systems found in metagenomic data and applied protein engineering approaches to enhance the editing efficiency of NanoCas. The optimized NanoCas exhibits potent editing capabilities across various cell systems and tissues in vivo when administered via adeno-associated viral (AAV) vectors. This is accomplished despite NanoCas being approximately one-third the size of conventional CRISPR nucleases. In proof-of-concept experiments, we observed robust editing with our optimized NanoCas in mouse models targeting Pcsk9, a gene involved in cholesterol regulation, and targeting exon splice sites in dystrophin to address Duchenne muscular dystrophy (DMD) mutations. We further tested the efficacy of our NanoCas system in vivo in non-human primates (NHPs) resulting in editing levels above 30% in muscle tissues. The compact size of NanoCas, in combination with robust nuclease editing, opens the door for single-AAV editing of non-liver tissues in vivo, including the use of newer editing modalities such as reverse transcriptase (RT) editing, base editing, and epigenetic editing.

bioengineering↗