CRISPR/Cas Applications in Myotonic Dystrophy: Expanding Opportunities

• Published in: International journal of molecular sciences Vol. 20; no. 15; p. 3689
• Main Authors: Raaijmakers, Renée H.L., Ripken, Lise, Ausems, C. Rosanne M., Wansink, Derick G.
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 27.07.2019; MDPI
• Subjects: Animals; Cell cycle; Cell- and Tissue-Based Therapy; CRISPR; CRISPR-Cas Systems; Deoxyribonucleic acid; Disease; DNA; DNA methylation; Gene Editing; Gene Targeting; Genetic Association Studies; Genetic Loci; Genetic Predisposition to Disease; Genetic Therapy; Genomes; Humans; Laboratories; Mutation; Myotonic Dystrophy - genetics; Myotonic Dystrophy - therapy; Proteins; Review; Trinucleotide Repeat Expansion; Trinucleotide Repeats; myotonic dystrophy; muscular dystrophy; repeat expansion; cell therapy; gene therapy; neuromuscular disease; trinucleotide repeat; gene editing
• DOI: 10.3390/ijms20153689
• ISSN: 1422-0067; 1661-6596

CRISPR/Cas technology holds promise for the development of therapies to treat inherited diseases. Myotonic dystrophy type 1 (DM1) is a severe neuromuscular disorder with a variable multisystemic character for which no cure is yet available. Here, we review CRISPR/Cas-mediated approaches that target the unstable (CTG•CAG)n repeat in the DMPK/DM1-AS gene pair, the autosomal dominant mutation that causes DM1. Expansion of the repeat results in a complex constellation of toxicity at the DNA level, an altered transcriptome and a disturbed proteome. To restore cellular homeostasis and ameliorate DM1 disease symptoms, CRISPR/Cas approaches were directed at the causative mutation in the DNA and the RNA. Specifically, the triplet repeat has been excised from the genome by several laboratories via dual CRISPR/Cas9 cleavage, while one group prevented transcription of the (CTG)n repeat through homology-directed insertion of a polyadenylation signal in DMPK. Independently, catalytically deficient Cas9 (dCas9) was recruited to the (CTG)n repeat to block progression of RNA polymerase II and a dCas9-RNase fusion was shown to degrade expanded (CUG)n RNA. We compare these promising developments in DM1 with those in other microsatellite instability diseases. Finally, we look at hurdles that must be taken to make CRISPR/Cas-mediated editing a therapeutic reality in patients.