Myotonic dystrophy type 1 (DM1), commonly known as Steinert’s disease (OMIM #160900), is the most common muscular dystrophy among adults, caused by an unstable expansion of a CTG trinucleotide repeat in the 3′ untranslated region (UTR) of DMPK. This evidence concerns the gene DMPK and myotonic dystrophy type 1.