Compact CRISPR system activates six genes from one viral package in mice

Researchers developed a compact CRISPR system that carried eight guides in a single viral package and increased the activity of six genes in mouse brain and muscle tissues. The work, published in Nature Biotechnology, addresses the limited cargo space of viruses used to deliver genetic instructions into cells. The system uses an engineered Cas12m protein to activate genes without cutting DNA and to separate a chain of RNA guides into working pieces. In separate disease-model experiments, treatment reduced seizures and prevented early deaths in Dravet syndrome mice, and improved muscle function in Duchenne muscular dystrophy mice. Both disease experiments treated very young mice. Further testing must assess doses, unintended effects and safety when altering several genes' activity.