DM type 1 (DM1; MIM #160900), also known as Steinert’s disease, is caused by the accumulation of cytosine-thymine-guanine (CTG) trinucleotide repeat expansions in the 3′ untranslated region of the dystrophia myotonic-protein kinase (DMPK) gene on chromosome 19q13.3 (2). This evidence concerns the gene DMPK and myotonic dystrophy type 1.