DMPK and myotonic dystrophy type 1: Dot‐blot analysis of the mutated DMPK transcript in dCas9‐expressing cells did not reveal a significant decrease in mutated DMPK transcript accumulation, unlike what was observed in cells expressing Cas9 (Figure S3B,D), suggesting that a functional nuclease activity is important to achieve a strong inhibitory effect in DM1 cells.