A CRISPR-Cas13a Based Strategy That Tracks and Degrades Toxic RNA in Myotonic Dystrophy Type 1.

Cas13a, an effector of type VI CRISPR-Cas systems, is an RNA guided RNase with multiplexing and therapeutic potential. This study employs the () Cas13a and a repeat-based CRISPR RNA (crRNA) to track and eliminate toxic RNA aggregates in myotonic dystrophy type 1 (DM1) - a neuromuscular disease caused by CTG expansion in the gene. We demonstrate that Cas13a cleaves CUG repeat RNA in biochemical assays and reduces toxic RNA load in patient-derived myoblasts. As a result, Cas13a reverses the characteristic adult-to-embryonic missplicing events in several key genes that contribute to DM1 phenotype. The deactivated Cas13a can further be repurposed to track RNA-rich organelles within cells. Our data highlights the reprogrammability of Cas13a and the possible use of Cas13a to target expanded repeat sequences in microsatellite expansion diseases.