DMPK and myotonic dystrophy type 1: While a (CTG)n expansion, ranging from 50 to several thousand CTGs, in the 3′UTR of DMPK causes DM1 [166,167,168], a (CCTG)n expansion, from 75 to 11,000 repeats, in intron 1 of CNBP is responsible for DM2 [169] (Figure 1).