Myotonic dystrophy (DM) is the most common inherited muscle dystrophy in adults and comprises two genetically distinct forms: DM type 1 (DM1, Steinert’ disease, OMIM 160900), caused by an expansion of CTG repeats in the 3′ untranslated region of the DM protein kinase (DMPK) gene (Brook et al., 1992) and DM type 2 (DM2, OMIM 602668), due to the expansion of CCTG repeats in the first intron of the cellular nucleic acid-binding protein (CNBP) gene, also named ZNF9 (zinc finger protein 9; Liquori et al., 2001). Here, DMPK is linked to myotonic dystrophy.