The genetic cause of DM1 is the expansion of unstable CTG‐repeats in the 3′ untranslated region (UTR) of the DMPK gene, resulting in the accumulation of toxic CUG‐transcripts that sequester RNA‐binding proteins and form nuclear foci in DM1 affected tissues and, consequently, alter various cellular processes. This evidence concerns the gene DMPK and myotonic dystrophy type 1.